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Seedless Plant Lab - Biology

Seedless Plant Lab - Biology


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Lab Objectives

At the conclusion of the lab, the student should be able to:

  • Explain what is meant by “alteration of generations”
  • Explain the difference between the sporophyte and gametophyte generation in plants. State which generation is haploid and which is diploid
  • Name the process that makes spores and state if spores are haploid or diploid
  • Name the process that creates sperm and egg from spores and state if sperm and egg are haploid or diploid
  • Name the phyla discussed in the lab and give an example of a plant from each
  • Identify and know the function of the archegonium and the antheridum
  • Identify the fern structures discussed
  • Understand the basic moss and fern life cycle

Seedless plants BIO II Slides from Lumen Learning

Procedure

  1. Access the page “Reading: Seedless Plants.”
  2. Phylum Bryophyta (Mosses)
    1. View the live moss specimens available in the lab.
      1. Is the green “leaf like” tissue gametophyte or sporophyte?
      2. Is the stalk that emerges from the green “leaf like” tissue gametophyte or sporophyte?
    2. As indicated in #3 of the website use the space below to draw a simple life cycle of the moss. Include in the life cycle 2N, N, sporophyte, gametophyte, meiosis, spores, egg, sperm, antheridium, archigonium, fertilization. If you need help in constructing your life cycle picture check out this website.
    3. View the prepared slide of the archigonium and the antheridum (there should be a slide with both).
      1. Is the archegonium male or female?
      2. What cell is produced in the archegonium?
      3. Is this cell haploid or diploid?
      4. Is the antheridium male or female?
      5. What cell is produced in the antheridium?
      6. Is this cell haploid or diploid?
    4. View the prepared slide of the moss capsule.
      1. Is the capsule sporophyte or gametophyte tissue?
      2. What cell is produced in the capsule?
      3. Is this cell haploid or diploid?
      4. How are moss spores dispersed to new locations?
  3. Skip the liverworts section (Phylum Hepatophyta)
  4. Seedless Vascular Plants
  5. Phylum Pterophyta (Ferns)
    1. As indicated in #1 of the website use the space below to draw a simple life cycle of the fern. Include in the life cycle 2N, N, sporophyte, gametophyte, meiosis, spores, egg, sperm, antheridium, archigonium, fertilization, sorus. If you need help in constructing your life cycle picture check out this website.
    2. Observe the preserved fern frond. Locate the sori on the underside.
      1. Is the frond sporophyte or gametophyte?
      2. What cell is produced in the sori?
      3. Is this cell diploid or haploid?
    3. View the prepared slide of the fern prothallus under the microscope.
      1. What shape is the prothallus?
      2. Is the prothallus sporophyte or gametophyte?
      3. Can you find the archegonium and the antheridium?
      4. What cell is made in the archegonium?
      5. What cell is made in the antheridium?
  6. Skip the horsetails
  7. Skip the spikemosses and club mosses (Phylum Kycophyta)
  8. Answer the review questions below.
    1. Is gametophyte tissue haploid or diploid?
    2. Is sporophyte tissue haploid or diploid?
    3. Is the moss life cycle gametophyte or sporophyte dominant?
    4. Is the fern life cycle gametophyte or sporophyte dominant?
    5. In the life cycle of the primitive plant, the process of meiosis produces what cell?
    6. Does the gametophyte or sporophyte generation produce spores?
    7. What process do spores undergo to create sperm and egg?
    8. State one reason why moss and fern are considered primitive plants.
    9. What is meant by the idea of “alteration of generations?”

LICENSES AND ATTRIBUTIONS

CC LICENSED CONTENT, SHARED PREVIOUSLY

  • Biology 102 Labs. Authored by: Lynette Hauser.

    Seedless Plant Lab - Biology

    Figure 1. Seedless plants, like these horsetails (Equisetum sp.), thrive in damp, shaded environments under a tree canopy where dryness is rare. (credit: modification of work by Jerry Kirkhart)

    An incredible variety of seedless plants populates the terrestrial landscape. Mosses may grow on a tree trunk, and horsetails may display their jointed stems and spindly leaves across the forest floor. Today, seedless plants represent only a small fraction of the plants in our environment yet, three hundred million years ago, seedless plants dominated the landscape and grew in the enormous swampy forests of the Carboniferous period. Their decomposition created large deposits of coal that we mine today.

    Current evolutionary thought holds that all plants—green algae as well as land dwellers—are monophyletic that is, they are descendants of a single common ancestor. The evolutionary transition from water to land imposed severe constraints on plants. They had to develop strategies to avoid drying out, to disperse reproductive cells in air, for structural support, and for capturing and filtering sunlight. While seed plants developed adaptations that allowed them to populate even the most arid habitats on Earth, full independence from water did not happen in all plants. Most seedless plants still require a moist environment.

    Learning Objectives

    • Describe the timeline of plant evolution and the impact of land plants on other living things
    • Describe the traits shared by green algae and land plants
    • Identify the main characteristics of bryophytes
    • Differentiate between vascular and non-vascular plants
    • Identify the main characteristics of seedless vascular plants

    Seedless Plant Lab - Biology

    . the Pterophyta (ferns) are collectively know as the "seedless vascular plants" . Most of the seedless vascular plants are homosporous, the spores grow into a .
    Full article >>>

    III. There are three phyla of extinct seedless vascular plants . A. The majority of extant seedless vascular plants belong to this phylum .
    Full article >>>

    I. Evolution of vascular plants (seedless & seed producing): A. To prevent desiccation: . 4 phyla of seedless vascular plants: A. Phylum Psilotophyta (only 2 .
    Full article >>>

    Chapter 19 -- SEEDLESS VASCULAR PLANTS . Sperm of seedless vascular plants still require water in order to swim to the egg. .
    Full article >>>

    . well understood vascular plants. seedless. simple, dichotomously branching . homosporous vs. heterosporous. characteristics of seedless vascular plants .
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    Although the sporophytes of seedless vascular plants can live on land, their . Seedless vascular plants typically live in wet, humid places. Whisk Ferns .
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    This site provides an overview and general characteristics of seedless vascular plants. . an example of seedless vascular plants at this informative station. .
    Full article >>>

    Seedless Vascular Plants. Outline. How do seedless vascular plants differ from bryophytes? Like bryophytes, vascular plants are mostly terrestrial: .
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    Seedless Vascular Plants. Review Questions: . 4. Which stage of alternation of generations dominates for the seedless. vascular plants? .
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    SEEDLESS VASCULAR PLANTS. Ferns and allies. Characteristics. No seed s. Vascular tiss ue prese n t . Most seedles s vascular plant s. Homo s p o r o u s .
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    Lab 4 Kingdom Plantae—Vascular Seedless Plants. Principles of Biology II Laboratory: . Seedless Vascular Plants. Phylum Psilophyta—whisk ferns. Phylum .
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    bryophytes and the seedless vascular plants, and discuss the differences . and Seedless Vascular Plants. For a . Seedless vascular plants dominated .
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    The three phyla of seedless vascular plants are lycophytes, horsetails, and ferns . Horsetails (Sphenophyta) are seedless vascular plants with underground rhizomes, .
    Full article >>>

    All of the seedless vascular plants have motile sperms and depend on water for fertilization. . PHYLA OF SEEDLESS VASCULAR PLANTS .
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    . Seedless Vascular Plants. Sporophyte stages of seedless vascular plants (Tracheophytes) . Name one function of the vascular tissue found in these plants. .
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    These plants were seedless vascular plants, which were propogated by spores. . The seedless vascular plants do not have this protection. .
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    Some of the seedless vascular plants produce a strobilus = a step tip with . Seedless Vascular Plants (Steven Wolf at California State University Stanislaus) .
    Full article >>>


    25.4 Seedless Vascular Plants

    By the end of this section, you will be able to do the following:

    • Identify the new traits that first appear in seedless tracheophytes
    • Discuss how each trait is important for adaptation to life on land
    • Identify the classes of seedless tracheophytes
    • Describe the life cycle of a fern
    • Explain the role of seedless plants in the ecosystem

    The vascular plants, or tracheophytes , are the dominant and most conspicuous group of land plants. More than 260,000 species of tracheophytes represent more than 90 percent of Earth’s vegetation. Several evolutionary innovations explain their success and their ability to spread to all habitats.

    Bryophytes may have been successful at the transition from an aquatic habitat to land, but they are still dependent on water for reproduction, and must absorb moisture and nutrients through the gametophyte surface. The lack of roots for absorbing water and minerals from the soil, as well as a lack of lignin-reinforced conducting cells, limit bryophytes to small sizes. Although they may survive in reasonably dry conditions, they cannot reproduce and expand their habitat range in the absence of water. Vascular plants, on the other hand, can achieve enormous heights, thus competing successfully for light. Photosynthetic organs become leaves, and pipe-like cells or vascular tissues transport water, minerals, and fixed carbon organic compounds throughout the organism.

    Throughout plant evolution, there is a progressive increase in the dominance of the sporophyte generation. In seedless vascular plants, the diploid sporophyte is the dominant phase of the life cycle. The gametophyte is now less conspicuous, but still independent of the sporophyte. Seedless vascular plants still depend on water during fertilization, as the flagellated sperm must swim on a layer of moisture to reach the egg. This step in reproduction explains why ferns and their relatives are more abundant in damp environments.

    Vascular Tissue: Xylem and Phloem

    The first plant fossils that show the presence of vascular tissue date to the Silurian period, about 430 million years ago. The simplest arrangement of conductive cells shows a pattern of xylem at the center surrounded by phloem. Xylem is the tissue responsible for the storage and long-distance transport of water and nutrients, as well as the transfer of water-soluble growth factors from the organs of synthesis to the target organs. The tissue consists of conducting cells, known as tracheids, and supportive filler tissue, called parenchyma. Xylem conductive cells incorporate the compound lignin into their walls, and are thus described as lignified. Lignin itself is a complex polymer: It is impermeable to water and confers mechanical strength on vascular tissue. With their rigid cell walls, the xylem cells provide support to the plant and allow it to achieve impressive heights. Tall plants have a selective advantage by being able to reach unfiltered sunlight and disperse their spores or seeds away from the parent plant, thus expanding the species’ range. By growing higher than other plants, tall trees cast their shadows on shorter plants and thereby outcompete them for water and precious nutrients in the soil.

    Phloem is the second type of vascular tissue it transports sugars, proteins, and other solutes throughout the plant. Phloem cells are divided into sieve elements (conducting cells) and cells that support the sieve elements. Together, xylem and phloem tissues form the vascular system of plants (Figure 25.16).

    Roots: Support for the Plant

    Roots are not well-preserved in the fossil record. Nevertheless, it seems that roots appeared later in evolution than vascular tissue. The development of an extensive network of roots represented a significant new feature of vascular plants. Thin rhizoids attached bryophytes to the substrate, but these rather flimsy filaments did not provide a strong anchor for the plant nor did they absorb substantial amounts of water and nutrients. In contrast, roots, with their prominent vascular tissue system, transfer water and minerals from the soil to the rest of the plant. The extensive network of roots that penetrates deep into the soil to reach sources of water also stabilizes plants by acting as a ballast or anchor. The majority of roots establish a symbiotic relationship with fungi, forming mutualistic mycorrhizae, which benefit the plant by greatly increasing the surface area for absorption of water, soil minerals, and nutrients.

    Leaves, Sporophylls, and Strobili

    A third innovation marks the seedless vascular plants. Accompanying the prominence of the sporophyte and the development of vascular tissue, the appearance of true leaves improved their photosynthetic efficiency. Leaves capture more sunlight with their increased surface area by employing more chloroplasts to trap light energy and convert it to chemical energy, which is then used to fix atmospheric carbon dioxide into carbohydrates. The carbohydrates are exported to the rest of the plant by the conductive cells of phloem tissue.

    The existence of two types of leaf morphology—microphylls and megaphylls—suggests that leaves evolved independently in several groups of plants. Microphylls ("little leaves") are small and have a simple vascular system. The first microphylls in the fossil record can be dated to 350 million years ago in the late Silurian. A single unbranched vein —a bundle of vascular tissue made of xylem and phloem—runs through the center of the leaf. Microphylls may have originated from the flattening of lateral branches, or from sporangia that lost their reproductive capabilities. Microphylls are seen in club mosses. Microphylls probably preceded the development of megaphylls ("big leaves"), which are larger leaves with a pattern of multiple veins. Megaphylls most likely appeared independently several times during the course of evolution. Their complex networks of veins suggest that several branches may have combined into a flattened organ, with the gaps between the branches being filled with photosynthetic tissue. Megaphylls are seen in ferns and more derived vascular plants.

    In addition to photosynthesis, leaves play another role in the life of the plants. Pine cones, mature fronds of ferns, and flowers are all sporophylls —leaves that were modified structurally to bear sporangia. In conifers, the commonly named pine cones, strobili are cone-like structures that contain sporangia.

    Ferns and Other Seedless Vascular Plants

    By the late Devonian period, plants had evolved vascular tissue, well-defined leaves, and root systems. With these advantages, plants increased in height and size. During the Carboniferous period (360 to 300 MYA), swamp forests of club mosses and horsetails—some specimens reaching heights of more than 30 m (100 ft)—covered most of the land. These forests gave rise to the extensive coal deposits that gave the Carboniferous its name. In seedless vascular plants, the sporophyte became the dominant phase of the life cycle.

    Water is still required as a medium of sperm transport during the fertilization of seedless vascular plants, and most favor a moist environment. Modern-day seedless tracheophytes include club mosses, horsetails, ferns, and whisk ferns.

    Phylum Lycophyta: Club Mosses

    The club mosses , or phylum Lycophyta , are the earliest group of seedless vascular plants. They dominated the landscape of the Carboniferous, growing into tall trees and forming large swamp forests. Today’s club mosses are diminutive, evergreen plants consisting of a stem (which may be branched) and microphylls (Figure 25.17). The phylum Lycophyta consists of close to 1,200 species, including the quillworts (Isoetales), the club mosses (Lycopodiales), and spike mosses (Selaginellales), none of which are true mosses or bryophytes.

    Lycophytes follow the pattern of alternation of generations seen in the bryophytes, except that the sporophyte is the major stage of the life cycle. Some lycophytes, like the club moss Lycopodium, produce gametophytes that are independent of the sporophyte, developing underground or in other locations where they can form mycorrhizal associations with fungi. In many club mosses, the sporophyte gives rise to sporophylls arranged in strobili, cone-like structures that give the class its name. Sporangia develop within the chamber formed by each sporophyll.

    Lycophytes can be homosporous (spores of the same size) or heterosporous (spores of different sizes). The spike moss Selaginella is a heterosporous lycophyte. The same strobilus will contain microsporangia, which produce spores that will develop into the male gametophyte, and megasporangia, which produce spores that will develop into the female gametophyte. Both gametophytes develop within the protective strobilus.

    Phylum Monilophyta: Class Equisetopsida (Horsetails)

    Horsetails, whisk ferns, and ferns belong to the phylum Monilophyta, with horsetails placed in the class Equisetopsida. The single genus Equisetum is the survivor of a large group of plants, known as Arthrophyta, which produced large trees and entire swamp forests in the Carboniferous. The plants are usually found in damp environments and marshes (Figure 25.18).

    The stem of a horsetail is characterized by the presence of joints or nodes, hence the name Arthrophyta (arthro- = "joint" -phyta = "plant"). Leaves and branches come out as whorls from the evenly spaced joints. The needle-shaped leaves do not contribute greatly to photosynthesis, the majority of which takes place in the green stem (Figure 25.19).

    Silica collected by in the epidermal cells contributes to the stiffness of horsetail plants, but underground stems known as rhizomes anchor the plants to the ground. Modern-day horsetails are homosporous. The spores are attached to elaters—as we have seen, these are coiled threads that spring open in dry weather and casts the spores to a location distant from the parent plants. The spores then germinate to produce small bisexual gametophytes.

    Phylum Monilophyta: Class Psilotopsida (Whisk Ferns)

    While most ferns form large leaves and branching roots, the whisk ferns , class Psilotopsida, lack both roots and leaves, probably lost by reduction. Photosynthesis takes place in their green stems, which branch dichotomously. Small yellow knobs form at the tip of a branch or at branch nodes and contain the sporangia (Figure 25.20). Spores develop into gametophytes that are only a few millimeters across, but which produce both male and female gametangia. Whisk ferns were considered early pterophytes. However, recent comparative DNA analysis suggests that this group may have lost both vascular tissue and roots through evolution, and is more closely related to ferns.

    Phylum Monilophyta: Class Polypodiopsida (True Ferns)

    With their large fronds, the true ferns are perhaps the most readily recognizable seedless vascular plants. They are also considered to be the most advanced seedless vascular plants and display characteristics commonly observed in seed plants. More than 20,000 species of ferns live in environments ranging from the tropics to temperate forests. Although some species survive in dry environments, most ferns are restricted to moist, shaded places. Ferns made their appearance in the fossil record during the Devonian period (420 MYA) and expanded during the Carboniferous (360 to 300 MYA).

    The dominant stage of the life cycle of a fern is the sporophyte, which consists of large compound leaves called fronds. Fronds may be either finely divided or broadly lobed. Fronds fulfill a double role they are photosynthetic organs that also carry reproductive organs. The stem may be buried underground as a rhizome, from which adventitious roots grow to absorb water and nutrients from the soil or, they may grow above ground as a trunk in tree ferns (Figure 25.21). Adventitious organs are those that grow in unusual places, such as roots growing from the side of a stem.

    The tip of a developing fern frond is rolled into a crozier, or fiddlehead (Figure 25.22). Fiddleheads unroll as the frond develops.

    On the underside of each mature fern frond are groups of sporangia called sori (Figure 25.23a). Most ferns are homosporous. Spores are produced by meiosis and are released into the air from the sporangium. Those that land on a suitable substrate germinate and form a heart-shaped gametophyte, or prothallus, which is attached to the ground by thin filamentous rhizoids (Figure 25.23b). Gametophytes produce both antheridia and archegonia. Like the sperm cells of other pterophytes, fern sperm have multiple flagella and must swim to the archegonium, which releases a chemoattractant to guide them. The zygote develops into a fern sporophyte, which emerges from the archegonium of the gametophyte. Maturation of antheridia and archegonia at different times encourages cross-fertilization. The full life cycle of a fern is depicted in Figure 25.24.

    Visual Connection

    Which of the following statements about the fern life cycle is false?

    1. Sporangia produce haploid spores.
    2. The sporophyte grows from a gametophyte.
    3. The sporophyte is diploid and the gametophyte is haploid.
    4. Sporangia form on the underside of the gametophyte.

    Link to Learning

    To see an animation of the life cycle of a fern and to test your knowledge, go to the website.

    Career Connection

    Landscape Designer

    Looking at the ornamental arrangement of flower beds and fountains typical of the grounds of royal castles and historic houses of Europe, it’s clear that the gardens’ creators knew about more than art and design. They were also familiar with the biology of the plants they chose. Landscape design also has strong roots in the United States’ tradition. A prime example of early American classical design is Monticello, Thomas Jefferson’s private estate. Among his many interests, Jefferson maintained a strong passion for botany. Landscape layout can encompass a small private space like a backyard garden, public gathering places such as Central Park in New York City, or an entire city plan like Pierre L’Enfant’s design for Washington, DC.

    A landscape designer will plan traditional public spaces—such as botanical gardens, parks, college campuses, gardens, and larger developments—as well as natural areas and private gardens. The restoration of natural places encroached on by human intervention, such as wetlands, also requires the expertise of a landscape designer.

    With such an array of necessary skills, a landscape designer’s education should include a solid background in botany, soil science, plant pathology, entomology, and horticulture. Coursework in architecture and design software is also required for the completion of the degree. The successful design of a landscape rests on an extensive knowledge of plant growth requirements such as light and shade, moisture levels, compatibility of different species, and susceptibility to pathogens and pests. Mosses and ferns will thrive in a shaded area, where fountains provide moisture cacti, on the other hand, would not fare well in that environment. The future growth of individual plants must be taken into account, to avoid crowding and competition for light and nutrients. The appearance of the space over time is also of concern. Shapes, colors, and biology must be balanced for a well-maintained and sustainable green space. Art, architecture, and biology blend in a beautifully designed and implemented landscape (Figure 25.25).

    The Importance of Seedless Plants

    Mosses and liverworts are often the first macroscopic organisms to colonize an area, both in a primary succession—where bare land is settled for the first time by living organisms, or in a secondary succession—where soil remains intact after a catastrophic event wipes out many existing species. Their spores are carried by the wind, birds, or insects. Once mosses and liverworts are established, they provide food and shelter for other plant species. In a hostile environment, like the tundra where the soil is frozen, bryophytes grow well because they do not have roots and can dry and rehydrate quickly once water is again available. Mosses are at the base of the food chain in the tundra biome. Many species—from small herbivorous insects to musk oxen and reindeer—depend on mosses for food. In turn, predators feed on the herbivores, which are the primary consumers. Some reports indicate that bryophytes make the soil more amenable to colonization by other plants. Because they establish symbiotic relationships with nitrogen-fixing cyanobacteria, mosses replenish the soil with nitrogen.

    By the end of the nineteenth century, scientists had observed that lichens and mosses were becoming increasingly rare in urban and suburban areas. Because bryophytes have neither a root system for absorption of water and nutrients, nor a cuticular layer that protects them from desiccation, pollutants in rainwater readily penetrate their tissues as they absorb moisture and nutrients through their entire exposed surfaces. Therefore, pollutants dissolved in rainwater penetrate plant tissues readily and have a larger impact on mosses than on other plants. The disappearance of mosses can be considered a biological indicator for the level of pollution in the environment.

    Ferns contribute to the environment by promoting the weathering of rock, accelerating the formation of topsoil, and slowing down erosion as rhizomes spread throughout the soil. The water ferns of the genus Azolla harbor nitrogen-fixing cyanobacteria and restore this important nutrient to aquatic habitats.

    Seedless plants have historically played a role in human life with uses as tools, fuel, and medicine. For example, dried peat moss , Sphagnum, is commonly used as fuel in some parts of Europe and is considered a renewable resource. Sphagnum bogs (Figure 25.26) are cultivated with cranberry and blueberry bushes. In addition, the ability of Sphagnum to hold moisture makes the moss a common soil conditioner. Even florists use blocks of Sphagnum to maintain moisture for floral arrangements!

    The attractive fronds of ferns make them a favorite ornamental plant. Because they thrive in low light, they are well suited as house plants. More importantly, fiddleheads of bracken fern (Pteridium aquilinum) are a traditional spring food of Native Americans, and are popular as a side dish in French cuisine. The licorice fern, Polypodium glycyrrhiza, is part of the diet of the Pacific Northwest coastal tribes, owing in part to the sweetness of its rhizomes. It has a faint licorice taste and serves as a sweetener. The rhizome also figures in the pharmacopeia of Native Americans for its medicinal properties and is used as a remedy for sore throat.

    Link to Learning

    Go to this website to learn how to identify fern species.

    By far the greatest impact of seedless vascular plants on human life, however, comes from their extinct progenitors. The tall club mosses, horsetails, and tree-like ferns that flourished in the swampy forests of the Carboniferous period gave rise to large deposits of coal throughout the world. Coal provided an abundant source of energy during the Industrial Revolution, which had tremendous consequences on human societies, including rapid technological progress and growth of large cities, as well as the degradation of the environment. Coal is still a prime source of energy and also a major contributor to global warming.

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      Seedless Plant Lab - Biology

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      Plant life on Earth consists of nonvascular, seedless vascular, and seed plants.

      While seed plants are the most widespread on Earth today, nonvascular plants were once one of the key features of the terrestrial landscape.

      Today, this group includes three phyla of small, herbaceous plants: mosses, liverworts, and hornworts-which include many aquatic species. These plants are often collectively called bryophytes.

      Like all plants, bryophytes alternate between haploid gametophyte&mdashhere, the main body of the moss-and diploid sporophyte stages during their life cycles. This process is called the alternation of generations.

      Unlike other plants, bryophytes have life cycles dominated by gametophytes. Bryophyte gametophytes are typically larger and live longer than their sporophyte counterparts which depend upon them for nourishment and protection.

      One major characteristic of the bryophytes is that they lack seeds and reproduce using spores produced by the diploid sporophyte. These spores then grow via mitosis to form the gametophyte.

      Fertilization in non-vascular plants still occurs using male and female gametes. However, instead of pollen, the male gametes of nonvascular plants are self-motile, requiring water-even in small amounts such as a light morning dew-to disperse and actively swim to the female gamete.

      Finally, the fertilized diploid egg, remaining attached to the gametophyte, grows via mitosis to form a new sporophyte.

      Bryophytes are also unique in that they lack extensive vascular tissue-with no true roots, leaves or stems-and therefore rely on diffusion through cells to distribute nutrients and water. This also means that they cannot reach large sizes, and often remain low-growing.

      So while today most plants on Earth grow from seeds, because of the many and varied adaptations of nonvascular plants, they continue to thrive in moist habitats across the globe.

      34.2: Non-vascular Seedless Plants

      The diverse plant life on Earth&mdashconsisting of nearly 400,000 species&mdashcan be divided into three broad categories based on biological characteristics: nonvascular, seedless vascular, and seed plants.

      Nonvascular Plants Were the First Plants on Earth

      Nonvascular plants that live today include liverworts, mosses, and hornworts&mdashcollectively and informally known as bryophytes.

      Nonvascular plants are characterized by a lack of extensive vascular tissue, and have no true roots, leaves, or stems. Another trait of this group is the use of spores rather than seeds to reproduce, and a life cycle dominated by the haploid, egg- and sperm-producing gametophyte stage.

      Because their sperm typically require water to reach an egg, nonvascular plants are often found in moist habitats and reproduce more successfully close to other members of their species.

      The Life Cycle of Nonvascular Plants

      In a typical bryophyte, haploid spores produced by the sporophyte will grow via mitosis to form a haploid gametophyte. Once mature, these gametophytes generate haploid gametes of either male (sperm) or female type (eggs), in structures called antheridia or archegonia.

      In the presence of water (even as little as a morning dew), the sperm will swim towards the archegonia in order to find and fertilize the eggs. Once fertilization is complete, the now diploid zygote will grow via mitosis from the gametophyte structure, forming a new sporophyte. Once mature, the sporophyte produces haploid spores, and the cycle begins again.

      Most Plants on Earth Today Are Seed Plants

      While most modern-day plants grow from seeds, nonvascular plants were once the primary colonizers of the terrestrial landscape. Today, these plants continue to thrive in moist environments around the world.

      Delwiche, Charles Francis, and Endymion Dante Cooper. 2015. &ldquoThe Evolutionary Origin of a Terrestrial Flora.&rdquo Current Biology 25 (19). [Source]

      Pires, Nuno D., and Liam Dolan. 2012. &ldquoMorphological Evolution in Land Plants: New Designs with Old Genes.&rdquo Philosophical Transactions of the Royal Society B: Biological Sciences 367 (1588): 508&ndash18. [Source]


      All plants are created equal.

      We have classes geared towards both tropical foliage plants as well as cannabis. We are located in metro Boston Massachusetts which gives us the ability to teach you a wider variety of plants than other labs can offer. Learn the latest processes in tissue culture for your favorite plants. You will leave with every bit of knowledge you need to set up and run a successful tissue culture lab. You will get a full breakdown of needed equipment, step by step guide of all stages of the tissue culture process, and a list of all chemicals and hormones needed for some of your favorite plants. You will also receive access to several comprehensive guides you can follow along at home!
      In our classes, we share the information the others leave out.


      Seeds vs. Seedless Plants

      Seed plants or spermatophytes are plants are seed-producing plants.

      Explanation:

      This means they reproduce through seeds.

      Answer:

      Seedless plants are the plants which do not produce seeds for multiplication.

      Explanation:

      The plants in Division Pteridophyta are seedless. These do not multiply by seeds as the plants in Division Spermatophyta.

      The life cycle pattern in both Pteridophyta and Spermatophyta is basically same.

      Plants in both divisions exhibit alternation of generations . Main plant body represents sporophytic generation and the gametophytic generation is reduced.

      The sporophyte reproduces asexually by meispores (n) . The meispores germinate to give rise to gametophytic generation. The gametophyte is haploid . It reproduces sexually by gametes. The Zygote develops into embryo that grows into mature sporophyte.

      Thus the sporophytic and gametophytic generatons follow each other in alternate sequence. This phenomenon is termed alternation of generations.

      The main difference in Pteridophytes and spermatophytes is that sporophyte in most of the pteridophytes (e.g. ferns) is homosporous whereas sporophyte in spermatophytes is always heterosporous.**

      The gametophyte in ferns is independent, though reduced and is exosporic . In hetrosporous forms there are separate male and female gametopytes. These are reduced and endosporic.

      The female gametophyte is reduced and is permanently retained in megasporangium (ovule) and thus embryo formed as a consequence of sexual reproduction is retained inside the ovule permanently. The ovule matures into seed.

      Heterspory is the most important evolutionary step that leads to the formation of seed.

      The seedless plants (ferns) are homosporous. Some pteridophytes like Sealginella are heterosporous These plants do not produced seeds but show initial steps towards the seed formation.


      Space Plants Lab

      University of Florida plant molecular biologists Robert Ferl and Anna-Lisa Paul lead a team focused on growing plants in space environments. Join them as they study plants currently on the International Space Station.

      Environmental changes almost always lead to changes in gene regulation. Our lab genetically engineers Arabidopsis thaliana plants to display their adaptation response to a specific kind of stress. We send these plants aboard the International Space Station to learn how biology reacts in microgravity. Our goal is to use this technology to identify the effects of space flight on plant biology. Astronauts aboard the Space Station take both macroscopic and microscope images of the plants as they grow, while the lab members on Earth monitor the experiments. At the end of the flight, the plants are fixed in a solution that preserves their on-orbit metabolic state. After the plants return to Earth, we perform genetic expression testing and other standard techniques to determine how the plants responded to their time in space.


      130 Seedless Vascular Plants

      By the end of this section, you will be able to do the following:

      • Identify the new traits that first appear in seedless tracheophytes
      • Discuss how each trait is important for adaptation to life on land
      • Identify the classes of seedless tracheophytes
      • Describe the life cycle of a fern
      • Explain the role of seedless plants in the ecosystem

      The vascular plants, or tracheophytes , are the dominant and most conspicuous group of land plants. More than 260,000 species of tracheophytes represent more than 90 percent of Earth’s vegetation. Several evolutionary innovations explain their success and their ability to spread to all habitats.

      Bryophytes may have been successful at the transition from an aquatic habitat to land, but they are still dependent on water for reproduction, and must absorb moisture and nutrients through the gametophyte surface. The lack of roots for absorbing water and minerals from the soil, as well as a lack of lignin-reinforced conducting cells, limit bryophytes to small sizes. Although they may survive in reasonably dry conditions, they cannot reproduce and expand their habitat range in the absence of water. Vascular plants, on the other hand, can achieve enormous heights, thus competing successfully for light. Photosynthetic organs become leaves, and pipe-like cells or vascular tissues transport water, minerals, and fixed carbon organic compounds throughout the organism.

      Throughout plant evolution, there is a progressive increase in the dominance of the sporophyte generation. In seedless vascular plants, the diploid sporophyte is the dominant phase of the life cycle. The gametophyte is now less conspicuous, but still independent of the sporophyte. Seedless vascular plants still depend on water during fertilization, as the flagellated sperm must swim on a layer of moisture to reach the egg. This step in reproduction explains why ferns and their relatives are more abundant in damp environments.

      Vascular Tissue: Xylem and Phloem

      The first plant fossils that show the presence of vascular tissue date to the Silurian period, about 430 million years ago. The simplest arrangement of conductive cells shows a pattern of xylem at the center surrounded by phloem. Xylem is the tissue responsible for the storage and long-distance transport of water and nutrients, as well as the transfer of water-soluble growth factors from the organs of synthesis to the target organs. The tissue consists of conducting cells, known as tracheids, and supportive filler tissue, called parenchyma. Xylem conductive cells incorporate the compound lignin into their walls, and are thus described as lignified. Lignin itself is a complex polymer: It is impermeable to water and confers mechanical strength on vascular tissue. With their rigid cell walls, the xylem cells provide support to the plant and allow it to achieve impressive heights. Tall plants have a selective advantage by being able to reach unfiltered sunlight and disperse their spores or seeds away from the parent plant, thus expanding the species’ range. By growing higher than other plants, tall trees cast their shadows on shorter plants and thereby outcompete them for water and precious nutrients in the soil.

      Phloem is the second type of vascular tissue it transports sugars, proteins, and other solutes throughout the plant. Phloem cells are divided into sieve elements (conducting cells) and cells that support the sieve elements. Together, xylem and phloem tissues form the vascular system of plants ((Figure)).


      Roots: Support for the Plant

      Roots are not well-preserved in the fossil record. Nevertheless, it seems that roots appeared later in evolution than vascular tissue. The development of an extensive network of roots represented a significant new feature of vascular plants. Thin rhizoids attached bryophytes to the substrate, but these rather flimsy filaments did not provide a strong anchor for the plant nor did they absorb substantial amounts of water and nutrients. In contrast, roots, with their prominent vascular tissue system, transfer water and minerals from the soil to the rest of the plant. The extensive network of roots that penetrates deep into the soil to reach sources of water also stabilizes plants by acting as a ballast or anchor. The majority of roots establish a symbiotic relationship with fungi, forming mutualistic mycorrhizae, which benefit the plant by greatly increasing the surface area for absorption of water, soil minerals, and nutrients.

      Leaves, Sporophylls, and Strobili

      A third innovation marks the seedless vascular plants. Accompanying the prominence of the sporophyte and the development of vascular tissue, the appearance of true leaves improved their photosynthetic efficiency. Leaves capture more sunlight with their increased surface area by employing more chloroplasts to trap light energy and convert it to chemical energy, which is then used to fix atmospheric carbon dioxide into carbohydrates. The carbohydrates are exported to the rest of the plant by the conductive cells of phloem tissue.

      The existence of two types of leaf morphology—microphylls and megaphylls—suggests that leaves evolved independently in several groups of plants. Microphylls (“little leaves”) are small and have a simple vascular system. The first microphylls in the fossil record can be dated to 350 million years ago in the late Silurian. A single unbranched vein —a bundle of vascular tissue made of xylem and phloem—runs through the center of the leaf. Microphylls may have originated from the flattening of lateral branches, or from sporangia that lost their reproductive capabilities. Microphylls are seen in club mosses. Microphylls probably preceded the development of megaphylls (“big leaves”), which are larger leaves with a pattern of multiple veins. Megaphylls most likely appeared independently several times during the course of evolution. Their complex networks of veins suggest that several branches may have combined into a flattened organ, with the gaps between the branches being filled with photosynthetic tissue. Megaphylls are seen in ferns and more derived vascular plants.

      In addition to photosynthesis, leaves play another role in the life of the plants. Pine cones, mature fronds of ferns, and flowers are all sporophylls —leaves that were modified structurally to bear sporangia. Strobili are cone-like structures that contain sporangia. They are prominent in conifers, where they are commonly known as pine cones.

      Ferns and Other Seedless Vascular Plants

      By the late Devonian period, plants had evolved vascular tissue, well-defined leaves, and root systems. With these advantages, plants increased in height and size. During the Carboniferous period (360 to 300 MYA), swamp forests of club mosses and horsetails—some specimens reaching heights of more than 30 m (100 ft)—covered most of the land. These forests gave rise to the extensive coal deposits that gave the Carboniferous its name. In seedless vascular plants, the sporophyte became the dominant phase of the life cycle.

      Water is still required as a medium of sperm transport during the fertilization of seedless vascular plants, and most favor a moist environment. Modern-day seedless tracheophytes include club mosses, horsetails, ferns, and whisk ferns.

      Phylum Lycopodiophyta: Club Mosses

      The club mosses , or phylum Lycopodiophyta , are the earliest group of seedless vascular plants. They dominated the landscape of the Carboniferous, growing into tall trees and forming large swamp forests. Today’s club mosses are diminutive, evergreen plants consisting of a stem (which may be branched) and microphylls ((Figure)). The phylum Lycopodiophyta consists of close to 1,200 species, including the quillworts (Isoetales), the club mosses (Lycopodiales), and spike mosses (Selaginellales), none of which are true mosses or bryophytes.

      Lycophytes follow the pattern of alternation of generations seen in the bryophytes, except that the sporophyte is the major stage of the life cycle. Some lycophytes, like the club moss Lycopodium, produce gametophytes that are independent of the sporophyte, developing underground or in other locations where they can form mycorrhizal associations with fungi. In many club mosses, the sporophyte gives rise to sporophylls arranged in strobili, cone-like structures that give the class its name. Sporangia develop within the chamber formed by each sporophyll.

      Lycophytes can be homosporous (spores of the same size) or heterosporous (spores of different sizes). The spike moss Selaginella is a heterosporous lycophyte. The same strobilus will contain microsporangia, which produce spores that will develop into the male gametophyte, and megasporangia, which produce spores that will develop into the female gametophyte. Both gametophytes develop within the protective strobilus.


      Phylum Monilophyta: Class Equisetopsida (Horsetails)

      Horsetails, whisk ferns, and ferns belong to the phylum Monilophyta, with horsetails placed in the class Equisetopsida. The single genus Equisetum is the survivor of a large group of plants, known as Arthrophyta, which produced large trees and entire swamp forests in the Carboniferous. The plants are usually found in damp environments and marshes ((Figure)).


      The stem of a horsetail is characterized by the presence of joints or nodes, hence the name Arthrophyta (arthro- = “joint” -phyta = “plant”). Leaves and branches come out as whorls from the evenly spaced joints. The needle-shaped leaves do not contribute greatly to photosynthesis, the majority of which takes place in the green stem ((Figure)).


      Silica collected by in the epidermal cells contributes to the stiffness of horsetail plants, but underground stems known as rhizomes anchor the plants to the ground. Modern-day horsetails are homosporous. The spores are attached to elaters—as we have seen, these are coiled threads that spring open in dry weather and casts the spores to a location distant from the parent plants. The spores then germinate to produce small bisexual gametophytes.

      Phylum Monilophyta: Class Psilotopsida (Whisk Ferns)

      While most ferns form large leaves and branching roots, the whisk ferns , class Psilotopsida, lack both roots and leaves, probably lost by reduction. Photosynthesis takes place in their green stems, which branch dichotomously. Small yellow knobs form at the tip of a branch or at branch nodes and contain the sporangia ((Figure)). Spores develop into gametophytes that are only a few millimeters across, but which produce both male and female gametangia. Whisk ferns were considered early pterophytes. However, recent comparative DNA analysis suggests that this group may have lost both vascular tissue and roots through evolution, and is more closely related to ferns.


      Phylum Monilophyta: Class Polypodiopsida (True Ferns)

      With their large fronds, the true ferns are perhaps the most readily recognizable seedless vascular plants. They are also considered to be the most advanced seedless vascular plants and display characteristics commonly observed in seed plants. More than 20,000 species of ferns live in environments ranging from the tropics to temperate forests. Although some species survive in dry environments, most ferns are restricted to moist, shaded places. Ferns made their appearance in the fossil record during the Devonian period (420 MYA) and expanded during the Carboniferous (360 to 300 MYA).

      The dominant stage of the life cycle of a fern is the sporophyte, which consists of large compound leaves called fronds. Fronds may be either finely divided or broadly lobed. Fronds fulfill a double role they are photosynthetic organs that also carry reproductive organs. The stem may be buried underground as a rhizome, from which adventitious roots grow to absorb water and nutrients from the soil or, they may grow above ground as a trunk in tree ferns ((Figure)). Adventitious organs are those that grow in unusual places, such as roots growing from the side of a stem.


      The tip of a developing fern frond is rolled into a crozier, or fiddlehead ((Figure)). Fiddleheads unroll as the frond develops.


      On the underside of each mature fern frond are groups of sporangia called sori ((Figure)a). Most ferns are homosporous. Spores are produced by meiosis and are released into the air from the sporangium. Those that land on a suitable substrate germinate and form a heart-shaped gametophyte, or prothallus, which is attached to the ground by thin filamentous rhizoids ((Figure)b). Gametophytes produce both antheridia and archegonia. Like the sperm cells of other pterophytes, fern sperm have multiple flagella and must swim to the archegonium, which releases a chemoattractant to guide them. The zygote develops into a fern sporophyte, which emerges from the archegonium of the gametophyte. Maturation of antheridia and archegonia at different times encourages cross-fertilization. The full life cycle of a fern is depicted in (Figure).



      Which of the following statements about the fern life cycle is false?

      1. Sporangia produce haploid spores.
      2. The sporophyte grows from a gametophyte.
      3. The sporophyte is diploid and the gametophyte is haploid.
      4. Sporangia form on the underside of the gametophyte.

      To see an animation of the life cycle of a fern and to test your knowledge, go to the website.

      Landscape Designer Looking at the ornamental arrangement of flower beds and fountains typical of the grounds of royal castles and historic houses of Europe, it’s clear that the gardens’ creators knew about more than art and design. They were also familiar with the biology of the plants they chose. Landscape design also has strong roots in the United States’ tradition. A prime example of early American classical design is Monticello, Thomas Jefferson’s private estate. Among his many interests, Jefferson maintained a strong passion for botany. Landscape layout can encompass a small private space like a backyard garden, public gathering places such as Central Park in New York City, or an entire city plan like Pierre L’Enfant’s design for Washington, DC.

      A landscape designer will plan traditional public spaces—such as botanical gardens, parks, college campuses, gardens, and larger developments—as well as natural areas and private gardens. The restoration of natural places encroached on by human intervention, such as wetlands, also requires the expertise of a landscape designer.

      With such an array of necessary skills, a landscape designer’s education should include a solid background in botany, soil science, plant pathology, entomology, and horticulture. Coursework in architecture and design software is also required for the completion of the degree. The successful design of a landscape rests on an extensive knowledge of plant growth requirements such as light and shade, moisture levels, compatibility of different species, and susceptibility to pathogens and pests. Mosses and ferns will thrive in a shaded area, where fountains provide moisture cacti, on the other hand, would not fare well in that environment. The future growth of individual plants must be taken into account, to avoid crowding and competition for light and nutrients. The appearance of the space over time is also of concern. Shapes, colors, and biology must be balanced for a well-maintained and sustainable green space. Art, architecture, and biology blend in a beautifully designed and implemented landscape ((Figure)).


      The Importance of Seedless Plants

      Mosses and liverworts are often the first macroscopic organisms to colonize an area, both in a primary succession—where bare land is settled for the first time by living organisms, or in a secondary succession—where soil remains intact after a catastrophic event wipes out many existing species. Their spores are carried by the wind, birds, or insects. Once mosses and liverworts are established, they provide food and shelter for other plant species. In a hostile environment, like the tundra where the soil is frozen, bryophytes grow well because they do not have roots and can dry and rehydrate quickly once water is again available. Mosses are at the base of the food chain in the tundra biome. Many species—from small herbivorous insects to musk oxen and reindeer—depend on mosses for food. In turn, predators feed on the herbivores, which are the primary consumers. Some reports indicate that bryophytes make the soil more amenable to colonization by other plants. Because they establish symbiotic relationships with nitrogen-fixing cyanobacteria, mosses replenish the soil with nitrogen.

      By the end of the nineteenth century, scientists had observed that lichens and mosses were becoming increasingly rare in urban and suburban areas. Because bryophytes have neither a root system for absorption of water and nutrients, nor a cuticular layer that protects them from desiccation, pollutants in rainwater readily penetrate their tissues as they absorb moisture and nutrients through their entire exposed surfaces. Therefore, pollutants dissolved in rainwater penetrate plant tissues readily and have a larger impact on mosses than on other plants. The disappearance of mosses can be considered a biological indicator for the level of pollution in the environment.

      Ferns contribute to the environment by promoting the weathering of rock, accelerating the formation of topsoil, and slowing down erosion as rhizomes spread throughout the soil. The water ferns of the genus Azolla harbor nitrogen-fixing cyanobacteria and restore this important nutrient to aquatic habitats.

      Seedless plants have historically played a role in human life with uses as tools, fuel, and medicine. For example, dried peat moss , Sphagnum, is commonly used as fuel in some parts of Europe and is considered a renewable resource. Sphagnum bogs ((Figure)) are cultivated with cranberry and blueberry bushes. In addition, the ability of Sphagnum to hold moisture makes the moss a common soil conditioner. Even florists use blocks of Sphagnum to maintain moisture for floral arrangements!


      The attractive fronds of ferns make them a favorite ornamental plant. Because they thrive in low light, they are well suited as house plants. More importantly, fiddleheads of bracken fern (Pteridium aquilinum) are a traditional spring food of Native Americans, and are popular as a side dish in French cuisine. The licorice fern, Polypodium glycyrrhiza, is part of the diet of the Pacific Northwest coastal tribes, owing in part to the sweetness of its rhizomes. It has a faint licorice taste and serves as a sweetener. The rhizome also figures in the pharmacopeia of Native Americans for its medicinal properties and is used as a remedy for sore throat.

      Go to this website to learn how to identify fern species based upon their fiddleheads.

      By far the greatest impact of seedless vascular plants on human life, however, comes from their extinct progenitors. The tall club mosses, horsetails, and tree-like ferns that flourished in the swampy forests of the Carboniferous period gave rise to large deposits of coal throughout the world. Coal provided an abundant source of energy during the Industrial Revolution, which had tremendous consequences on human societies, including rapid technological progress and growth of large cities, as well as the degradation of the environment. Coal is still a prime source of energy and also a major contributor to global warming.

      Section Summary

      The seedless vascular plants show several features important to living on land: vascular tissue, roots, and leaves. Vascular systems consist of xylem tissue, which transports water and minerals, and phloem tissue, which transports sugars and proteins. With the development of the vascular system, leaves appeared to act as large photosynthetic organs, and roots to access water from the ground. Small uncomplicated leaves are termed microphylls. Large leaves with vein patterns are termed megaphylls. Modified leaves that bear sporangia are called sporophylls. Some sporophylls are arranged in cone structures called strobili.

      The support and conductive properties of vascular tissues have allowed the sporophyte generation of vascular plants to become increasingly dominant. The seedless vascular plants include club mosses, which are the most primitive whisk ferns, which lost leaves and roots by reductive evolution and horsetails and ferns. Ferns are the most advanced group of seedless vascular plants. They are distinguished by large leaves called fronds and small sporangia-containing structures called sori, which are found on the underside of the fronds.

      Both mosses and ferns play an essential role in the balance of the ecosystems. Mosses are pioneering species that colonize bare or devastated environments and make it possible for succession to occur. They contribute to the enrichment of the soil and provide shelter and nutrients for animals in hostile environments. Mosses are important biological indicators of environmental pollution. Ferns are important for providing natural habitats, as soil stabilizers, and as decorative plants. Both mosses and ferns are part of traditional medical practice. In addition to culinary, medical, and decorative purposes, mosses and ferns can be used as fuels, and ancient seedless plants were important contributors to the fossil fuel deposits that we now use as an energy resource.

      Visual Connection Questions

      (Figure) Which of the following statements about the fern life cycle is false?


      Seedless Plant Lab - Biology

      Jun 30, 2021 – How plants quickly adapt to shifting environmental conditions [click to view]

      Mar 25, 2021 – New protein helps carnivorous plants sense and trap their prey [click to view]

      Nov 18, 2020 – Five Salk professors named among most highly cited researchers in the world [click to view]

      Nov 09, 2020 – Salk Institute and Sempra Energy announce project to advance plant-based carbon capture and storage research [click to view]

      Oct 01, 2020 – Joanne Chory wins the 2020 Pearl Meister Greengard Prize [click to view]

      Feb 24, 2020 – The Salk Institute to receive $12.5 million gift from Hess Corporation to accelerate development of plant-based carbon capture and storage [click to view]

      Nov 21, 2019 – Eight Salk professors named among most highly cited researchers in the world [click to view]

      Oct 30, 2019 – Salk Institute hits play on new podcast series [click to view]

      Apr 19, 2019 – Editing of RNA may play a role in chloroplast-to-nucleus communication [click to view]

      Apr 16, 2019 – Salk Institute initiative to receive more than $35 million to fight climate change [click to view]

      Dec 07, 2018 – Trio of Salk scientists named among most highly cited researchers in the world [click to view]

      May 10, 2018 – Salk Institute’s Joanne Chory awarded prestigious Gruber Prize [click to view]

      Jan 08, 2018 – Self-defense for plants [click to view]

      Jan 02, 2018 – Salk scientists Joanne Chory and Terrence Sejnowski named to National Academy of Inventors [click to view]

      Dec 03, 2017 – Salk Institute’s Joanne Chory awarded prestigious Breakthrough Prize in Life Sciences [click to view]

      Jul 26, 2017 – How plant architectures mimic subway networks [click to view]

      Jul 06, 2017 – How plants grow like human brains [click to view]

      Feb 10, 2016 – Three Salk scientists make Thomson Reuters’ list of “The World’s Most Influential Scientific Minds” [click to view]

      Dec 24, 2015 – Here comes the sun: cellular sensor helps plants find light [click to view]

      Oct 22, 2015 – Cellular damage control system helps plants tough it out [click to view]

      Apr 29, 2013 – Smoke signals: How burning plants tell seeds to rise from the ashes [click to view]

      Feb 05, 2013 – Plants cut the mustard for basic discoveries in metabolism [click to view]

      Apr 15, 2012 – Salk scientists discover how plants grow to escape shade [click to view]

      Jan 20, 2012 – Salk professor Joanne Chory awarded 2012 Genetics Society of America Medal [click to view]

      Jun 13, 2011 – Plant receptors reflect different solutions for signaling problem [click to view]

      May 24, 2011 – Salk professor, Joanne Chory, elected to Royal Society [click to view]

      Jan 31, 2011 – Different evolutionary paths lead plants and animals to the same crossroads: tyrosine phosphorylation [click to view]

      Jun 25, 2010 – Connecting the dots: How light receptors get their message across [click to view]

      Feb 27, 2009 – Light or fight? Scientists discover how plants make tough survival choices [click to view]

      Sep 16, 2008 – Biologists Identify Genes Controlling Rhythmic Plant Growth [click to view]

      Apr 03, 2008 – A place in the sun [click to view]

      Mar 29, 2007 – All roads lead to GUN1 [click to view]

      Mar 15, 2007 – Plant size morphs dramatically as scientists tinker with outer layer [click to view]

      Aug 10, 2006 – Computational analysis shows that plant hormones often go it alone [click to view]

      May 03, 2006 – Salk scientists untangle steroid hormone signaling in plants [click to view]

      Nov 04, 2005 – Salk Institute plant biologist named AAAS Fellow [click to view]

      Jan 27, 2005 – Plant Hormone Discovery Offers Potentially Increased Crop Yield [click to view]

      Jun 18, 2003 – Salk Scientists Identify Pathway That Determines When Plants Flower [click to view]

      Nov 16, 2001 – Global Plant Study by Salk Scientists Identifies Light-Adjusting Gene [click to view]

      Dec 13, 2000 – First Plant Genome Sequenced: Salk Scientists Part Of International Effort [click to view]

      Dec 20, 1999 – Plant “DWARF” Gene Found By Salk Scientists [click to view]


      Team Members

      • Lorenzo Rossi, Ph.D. – PI
      • Laura Muschweck - Biological Scientist I
      • Ricardo A. Lesmes-Vesga – Ph.D. Student
      • John M. Santiago – Ph.D. Student
      • Jonathan Clavijo Herrera– Ph.D. Student
      • Lukas M. Hallman – M.S. Student
      • John-Paul Fox – Research Technician
      • Julio Quinones – Undergraduate Research Intern


      Watch the video: Seedless Vascular Plants ferns (February 2023).