Exam 3 (Lecture 17 - 26)

Selaginella

Spike Moss Roots are typically borne on a rhizospore - leafless branches - that extends from the stem 2 rows of small leaves above lower larger leaves Ligule: its evolutionary origin is obscure; Functionally ligules are believed to be secretory organs that, by exuding water and possibly mucilage, serve to keep young leaves and sporangia moist; Short lived structures, they become shrunken and inconspicuous in older leaves; The ligule was a characteristic feature of the extinct giant Lycophytes such as Lepidodendron.

Homosporous Life Cycle

Sporangia produce spore mother cells (2n) Spore mother cells form spores (n) by meiosis Spores are the unit of dispersal Spore produces bisexual gametophytes Gametophytes exhibit exosporic development

Lycopodium

Sporophyll Sporangium (kidney bean shaped)

How do hornworts differ from liverworts?

Sporophyte shaped like a tapered horn Sporophyte has an intercalary meristem (a meristem developing between regions or mature tissue) Can grow indetermineately

Origin of the seed

The seed is the most complex and evolutionary successful method of sexual reproduction found in vascular plants

Characteristics of Gymnosperms

The term comes from the word gymnospermos, meaning naked seeds after the unenclosed condition of their seeds (called ovules in their unfertilized state) *Vegetative Characteristics*: Woody; Xylem - Tracheids (exceptions in Gnetophyta) *Reproductive Characteristics*: Sporophylls are usually aggregated in unisexual cones; Single integument (exceptions in Gnetophyta); Wind pollenated (exception in Cycads and Gnetophyta); Early free-nuclear division of female gametophyte; Early free-nuclear division of embryo (exceptions in some Gnetophyta); Cleavage polyembryony - single zygote gives rise to multiple embryos. The mature seed normally has only one embryo

What did vascular plants inherit from their bryophyte-like ancestors?

Tissue-producing meristems Gametangia Embryos and the sporophytes that develop from them Stomata Cuticles Sporopollenin - walled spores Precursors for vascular tissue

Anthoceros

Hornwort Lengthwise split in the upper part of erect sporophyte just below the apex where numerous haploid spores have been released. The ribbon-like multicellular pseudo-elaters that change shape as they dry out and presumably aid in the dispersal of spores. They are not true elaters because they are not derived from the same mother cell as the spores

Modern Lycophytes

Include topical species that grow on trees as epiphytes, using the trees as substrates, not as hosts Others grow on the forest floor in temperate regions The Lycophyte sporophytes are characterized by upright stems with many Microphylls and horizontal stems along the ground surface Adventitious roots extend down from the horizontal stems Specialized leaves (sporophylls, bear sporangia) often clustered to form club-shaped cones (strobilus) Spores are released from sporangia They develop into tiny, inconspicuous haploid gametophytes These may be either green aboveground plants or non-photosynthetic underground plants that are nurtured by symbiotic fungi Biflagellate sperm - like bryophytes

Three Phyla of Bryophytes

Liverworts Hornworts Mosses

Vascular Plants

Modern vascular plants have food transport tissues (phloem) and water conducting tissues (xylem) with lignified cells In vascular plants, the branched sporophyte is dominant and is independent of the parent gametophyte The first vascular plants were seedless Living vascular plants: True stems, leaves, and roots Vascular plants today: Trachophytes --> Lycophytes and Euphyllophytes

Major Features of Bryophytes

No vascular tissue Short-lived Unbranched One terminal sporangium Permanently attached and parasitic on gametophyte Dominant Basically unisexual

Gametophyte (1n or haploid)

Produces gametes

Sporophyte (2n or Diploid)

Produces spores; where meiosis occurs

Homospory vs. Heterospory

*Homospory*: Spores are the unit of dispersal; spores produce bisexual gametophytes; Gametophytes exhibit exosporic (outside the spore wall) development; Living examples include whisk ferns, lycopods, horsetails, and most ferns; Water required for fertilization *Heterospory*: Spores are the unit of dispersal; Spore produces unisexual gametophytes; Gametophytes are much smaller that ones from homosporous spores; Living examples include spike mosses, quillworts, some ferns, and all seed plants; Water required for fertilization

Compare Liverworts, Mosses and Hornworts Gametophytes

*Liverworts*: Leafy or Thallose; Flat and Prostrate, No mucilage cavities; Chloroplasts small, usually numerous, without pyrenoids; Oil Bodies *Mosses*: Leafy; Upright; No mucilage cavities; Chloroplasts small, usually numerous, without pyrenoids; No oil bodies *Hornworts*: Thallose; Flat and Prostrate; Mucilage Cavities with Cyanobacteria; Chloroplast large, usually 1 per cell with Pyrenoids; No oil bodies

Compare Liverworts, Mosses, and Hornworts Sporophytes

*Liverworts*: Short lived; Usually colorless; No Stomates; Distinct sporangium without central column; opening by 4 lines; No peristome teeth; Elaters *Mosses*: Short to Medium-lived; Green; Stomates Sometimes; Distinct sporangium with central column; Opening by circular hole; usually peristome teeth; No elaters *Hornworts*: Long-lived; Green; Stomates; No sporangium with central column; opening by 2 lines; No peristome teeth; Elaters but different

Cushiony Moss

Erect gametophyte with little branching, terminal sporophyte

Features Land Plants Share with Charophyte Algae

*Pigments*: Chlorophyll a and b; carotenoids *Chloroplasts*: similar structure in which thylakoid membranes are stacked as grana *Food Reserve*: starch *Cell Walls*: Cellulose (both 22-26%) rosette cellulose-synthesizing complexes, plasmodesmata *Sporopollenin*: the most durable organic material known, protects charophytes from desiccation; Sporopollenin is found in the spore and pollen walls of land plants *Cell Division*: Cell plate (Phragmoplast) *Body Structure*: Apical growth, multicellular, branched, nodes and internodes *Sexual Reproduction*: Oogmamy *DNA*: Sequence data supports close relationship between these groups

Three Moss Classes

*True Mosses*: Protonema with a single row of cells with slanted cross walls; Leafy gametophytes develop from minute budlike structures *Peat Mosses*: Protonema with plate of cells that is one layer thick; Gametophytes with clusters of branches, 5 per node; Explosive capsular operculum *Granite Mosses*: Protonema with 2 or more rows of cells; Capsule dehisces by splitting in four; Rhizoids occur in 2 rows; Mountainous or artic regions on rocks

Granite Moss

Class Andreaidae 2 genera Blackish-green/dark reddish brown Lives on granite or calcareous rocks in mountains Slits in capsule = spore discharge

Three Variations of Gametophyte/Sporophyte Relationships in Land Plants

1. Sporophyte dependent on gametophyte (bryophytes) 2. Large sporophyte and small, independent gametophyte (Ferns) 3. Reduced gametophyte dependent on sporophyte (Seed Plants)

Salviniaceae

2 Genera, about 13 species, tropical and warm-temperature Sori are enclosed within a sporocarp (microsporangia and Megasporangia are in different sporocarps) In Salvinia: leaves in whorls of 3, one of the 3 resembles a submerged root In Azolla: leaves divided into 2 lobes, one photosynthetic (with cavities that house nitrogen-fixing bacteria), the other submersed and non-photosynthetic; all free-floating aquatic

Psilotales

2 Genera: Psilotum (Whisk Fern) and Tmesipteris (Fork Fern) Often epiphytes Their dichotomous branching and lack of true leaves and roots seemed similar to early vascular plants However, comparisons of DNA sequences and ultrastructure, indicate that the lack of true roots and leaves evolved secondarily

Marsileaceae

3 Genera, about 80 species, tropical and temperate Sori are enclosed within a sporocarp (microsporangia and Megasporangia within the same sporocarp) Sporocarp is stalked and arises from the rhizome or petiole Rooted-aquatic (often with floating leaves) or terrestrial Marsilea, Pilularia, and Regnelidium

Mosses

9500 Species 3 Classes: Peat Moss, Granite or Rock Moss, and True Moss *Not mosses*: Reindeer Moss, Clubmoss, and Spanish Moss

Origin of Sporophytes

A mutation the delayed meiosis until one or more mitotic divisions of the zygote had occurred This multicellular, diploid sporophyte would have more cells available for meiosis, increasing the number of spores produced per zygote More spores = more potential gametophytes = better chance of survival on land

Indusium

A thin membrane covering the sorus, which often shrivels away when spores are ready to be dispersed True Indusium False Indusium Indusium Absent

Ophioglossaceae

Adder's Tongue Family Genera: Ophioglossum (Adder's Tongue Fern); Botrychium (Moonwort); Sceptridium (Grape Ferns); Botrypus (Rattlesnake Ferns) Perennial herbs with short, erect unbranched stems Leaves usually one or two per year Eusporangia without an annulus Vernation not circinate manner in which a fern frond emerges from the ground Most closely related to Psilotaceae Two rows of fused sporangia

Tobacco

After caffeine and alcohol it is the third most widely used psychoactive drug in the world People used to believe it had medicinal properties

Lysergic Acid Diethylamide (LSD )

Albert Hofmann (1938) LSD was a cultural phenomenon (Timothy Leary) in the 1960s and 1970s and was the psychedelic drug of choice LSD psychological effects (colloquially called a "trip"- Good and Bad Trips) very greatly from person to person, depending on factors such as previous experiences, state of mind and environment, as well as dose strength Trips also vary from one trip to another and even as time passes during a single trip The infatuation with LSD lasted for a number of years until considerable negative publicity emerged on bad trips LSD users quickly develop a high degree of tolerance for the drug's effects Tolerance for LSD is short-lived if it is lost if the user stops taking the drugs for several days There is no evidence that LSD produces physical withdrawal symptoms when chronic use is stopped Long-term effects: Persistent hallucinogen perceptual disorder (flashbacks); these episodes are spontaneous, repeated, sometimes continuous recurrences of some of the sensory distortions originally produced by LSD May include hallucinations, but it most commonly consists of visual disturbances such as: seeing false motion on the edges of the field of vision, bright or colored flashes; discoloration of visual field - halos (purple haze); trails attached to moving objects The causes of these effects, which in some users occur after a single experiences with the drug are not known This condition is typically persistent and in some cases remains unchanged for years after individuals have stopped using the rug

Features of Plants in Aquatic Habitats

All cells surrounded or close to water Dissolved minerals Dissolved CO2 and O2 Water supports weight of the plant (gravity neutral) Unicellular reproductive structures Mobile gametes All cells photosynthetic

Tracheophyte Evolution

Big split between Lycophyte lineage and Euphyllophytes Lycophytes have Microphylls Club Mosses, Spoke Mosses and Quillworts - often dichotomously branched or one branch may overgrow the other to exhibit pseudomonopodial growth; biflagellate sperm; chloroplast DNA sequence like bryophytes Euphyllophytes have Megaphylls and Chloroplast DNA Inversion Monilophytes: Five Major Lineages: whisk ferns, ophioglossoid ferns, horsetails, marattiod ferns, and leptosporangiate ferns; Multiflagellate sperm; Stellar Anatomy more complex Lignophytes: Progymnosperms (non-seed), Seed Ferns, Gymnosperms, and Flowering Plants; Secondary Growth; Secondary Xylem and Phloem; All heterosporous; Most (not all) with non-flagellate sperm

Eusporangiate Ferns

Botrychium (Grape Ferns) Ophioglossum (Adder's Tongue Fern) Leaves with a simple (Ophioglossum) or dissected sterile segments (Botrychium, Sceptridium, Botrypus) and a long-stalked fertile segment bearing numerous large sporangia Large and wall is multilayered

Hornworts

Cells of the gametophyte, each with a single large chloroplast. A single chloroplast is common in green algae but is quite unusual for multicellular plants Both gametophyte and sporophyte have stoma-like structures (the only known occurrence of a stomata in a gametophyte) - stoma do not open and close

True Moss

Class Bryidae Greatest diversity Have rhizoids Unisexual/Bisexual Fertilized with water, wind, and insects Sporophyte on top of gametophyte Sporangia mature 6-18 moths Undeveloped vascular system Stomata on sporophyte (like hornworts) Asexual reproduction by fragmentation, propagules (bulbils), and Gemma) Cushiony moss Feathery Moss

Peat Moss

Class Sphagnidea Distinctive Characteristics: protonema (young gametophyte ) is plate like, 1 cell thick and with marginal meristem; gametophyte "stem" tops bear 5 branches/nodes - thus mop like; leaves 1 cell thick with living cells surrounding large dead patches; perforated stems and dead leaf cells = high water holding capacity, 20x dry weight; decay resistant, lowers pH; explosive operculum Used as fuel, potting media Peat lands = 1% earths surface (stores 400 billion metric tons of carbon)

Feathery Moss

Creeping gametophyte with lots of branches, lateral sporophyte

Zygote

Diploid cell produced by fertilization; first cell of sporophyte

Spore Mother Cells

Diploid cells within sporangium that undergo meiosis to produce spores; last of the sporophyte generation

Advantages of Seeds

Embryo, food supply, and protective seed coat Seed dispersal - the seed is the unit of dispersal - not megaspores Seeds may remain dormant for years Evolution of pollen - pollen eliminates the need for water in fertilization

Equisetales

Equisetum is the last surviving genus of a once widespread and diverse division that included the huge, tree-like plants of the Carboniferous Equisetophytes are commonly called Horsetails because of their often bushy appearance During the Carboniferous, Equisetophytes grew to 18+ meters, but today they survive as about 15 species in a single widespread genus, Equisetum Stems jointed (Dimorphic) Equisetum usually has a rough texture due to siliceous deposits in the epidermal cells (Scouring Rush)

Monilophytes

Ferns, Whisk Ferns, and Horsetails Monilophyta is similar to the traditional group known as the Pteridophytes (ferns and fern allies), which consisted of all the seedless vascular plants However, the Lycophytes were considered Pteridophytes but are excluded from the Monilophytes Share a distinctive vasculature, having mesarch protoxylem confined to lobes of the xylem strand, therefore the Latin moniliformis appellation for "necklace-like"

Tmesipteris

Fork Fern Epiphyte Leaves With a single vein (Microphylls or flattened stem?) Homosporous Note fused, pair sporangia fused - synangium

Ergot and Ergotism

Fungus Parasite - Claviceps Purpurea Disease called Ergotism Infects grasses and grains - especially rye, wheat French word meaning spur Brown-black-purple body (sclerotium) Ergotamine - alkaline ca .1% of the body Can cause hallucinations resembling those produced by LSD Ergotism has been a problem ever somce grains used for food Results from ingestion when ergots ground into flour - rye bread First major outbreak of ergotism in Rhine Valley "Holy Fire" Symptoms: Victim's toes, fingers, arms and legs often become blackened as a result of gangrene, and would eventually die from the infections in these extremities (Gangrenous Symptoms - "Saint Anthony's Fire" and Convulsive Symptoms - "Saint Vitus' Dance")

Gametangia (singular: Gametangium)

Gametophytic sex organs Antheridium (Male) Archegonium (Female)

Sceptridium

Grape Fern Blades are dissected Fertile segment attached to the sterile segment or below ground level Large Eusporangia

Spores

Haploid cells, produced by meiosis; first cell of gametophytes

Gametes

Haploid cells, produced by mitosis, unite by fertilization; last of the gametophyte generation Sperm and Eggs

What were some major changes that appeared in vascular plants?

Have true vascular tissue (xylem and phloem) Dominant sporophyte generation Branched sporophytes Earliest vascular plants are seedless

Evolutionary Steps for the Colonization of Land

How to protect plant from drying out How to disperse gametes in drier environment How to protect zygote (and embryo) from drying out How to take up water and nutrients from below ground How to take up CO2 from the air How to resist gravity How to transport water and nutrients long distances

Hydroids

Hydroids do not have secondary wall thickenings The Equistem (a vascular plant) tracheid has secondary wall thickenings The moss hybrid lacks the secondary wall thickenings - however it has the same overall shape of a tracheid - the cells are dead and lack protoplasm Experiments have shown that water moves faster through hydroids compared to other cells

Sporic Meiosis

Land plants have both a multicellular diploid sporophyte and a multicellular haploid gametophyte Mitosis forms gametes Meiosis does not form gametes - spores (unit of dispersal) Haploid spores - reproductive cells that grow into a gametophyte by mitosis

Progymnosperms

Late Paleozoic Characteristics intermediate between seedless vascular plants and seed plants Reproduced by spores - some homosporous and some heterosporous Bifacial Vascular Cambium - characteristic of seed plants Secondary xylem similar to living conifers Both secondary vascular tissue and Heterospory predates the seed

Leptoids

Leptoids are cells specialized for the transportation of sugars They are analogous to sieve elements Leptoids have callose which is typically found in sieve elements of other land plants

Filicales

Leptosporangiate Ferns Sporangium develops entirely from a single cell The number of spores produces is a multiple of 2 between 16 and 512 Annulus Most produce clusters of sporangia, sori on the underside of green leaves (sporophylls) or on special non-green leaves Sori can be arranged in various patterns that are useful in fern identification Most leptosporangiate ferns are homosporous; a few aquatic genera are heterosporous After fertilization, the zygote develops in the venter of the archegonium - the zygote will grow into a new fern sporophyte with leaf, stem, and roots

Marchantia

Liverwort Thalli grow up to 10 cm long with a width of up to 2 cm Pores on upper surface Lower surface with rhizoids Gemma Cups (splash cups) - asexual reproduction: sperm are released onto the splash platforms and experiments with water droplets have shown that the sperm can be splashed 40-60 cm away Antehridiophores Archegoniophores

Heterosporic Life Cycle

Megasporangia produce megaspore mother cells (2n) Megaspore mother cells form megaspores (n) by meiosis Megaspores are the unit of dispersal Spore produces unisexual gametophyte Gametophytes exhibit endosporic development

Evolution of Leaves

Microphylls: evolved as outgrowths (enations) Megaphylls: evolved by a fusion of branch systems

Phylum Lycophtya

Modern Lycophytes are relicts of a far more eminent past By the Carboniferous period, Lycophytes existed as either small, herbaceous plants or as giant trees with diameters of over 2 meters and heights over 50 meters The giant Lycophytes (such as Lepidodendron) thrived in warm, moist swamps, but became extinct when the climate became cooler and drier Important in the formation of coal Lepidodendron has been likened to a giant herb, The trunks produced little wood, being mostly soft tissues The smaller Lycophytes survived and are represented by about 1,000 species today (less than 1% of extant vascular plants)

Azolla

Mosquito Fern Small, free-floating heterosporous leptosporangiate ferns Warm temperate and tropical regions throughout the world Foliage is bright green in shade, but develops purplish-rose tints in full sun - all plats turn reddish-purple in fall as temperature cools Roots hanging from plants floating on the water surface The tiny leaves are alternately arranged in 2 rows on the upper side of the stem and overlap like roof tiles (2 lobes) Sporocarps are borne in pairs on the first leaf of each branch, the lower lobe forming the sporocarp and the upper lobe forming a false Indusium over the sporocarp: the male sporocarp is much larger and contains many sporangia which contain many spores; the female sporocarp contains only one megasporangium with a single functioning megaspore

Asexual Reproduction of True Moss

Moss Propagules: The protonema forms a clump of cells that can become asexual, brown propagules called bulbils that can withstand cold, heat, or drought. The bulbils will develop into typical moss gametophytes when they reach a favorable environment Moss Gemma

How did vascular tissue evolve?

Mosses like Polytrichium produce xylem-like Hydroids and phloem-like Leptoids. These are present in the central strand of the stem ad in leaves as well. These specialized cell types are far more developed in the mosses compared to the liverworts Leptoids and Hydroids are elongated cells with overlapping end walls - this is consistent with their function as conducting cells. They appeal similar to those of fossil protracheophytes (lacking lignified vascular tissues)

Embryo

Multicellular entity that develops from zygote, and then into the mature sporophyte

Generalities About the Plant Kingdom

Multicellular eukaryotes that are photosynthetic and autotrophic Most are terrestrial (some have returned to water) Plants are immobile --> evolved to cope with stress (water loss, consumers, mechanical damage, temperature extremes, pathogens, odd soils, etc.) Prior to the origin and diversification of green plants in the mid-Silurian (about 450 mya) multicellular life was virtually entirely adapted to and confined to aquatic lifestyles - continental land masses virtually unoccupied by multicellular organisms Terrestrial life in a gaseous medium required evolutionary solutions to structural, physiological, and ecological challenges Many of these innovations can be regarded as adaptations of preexisting traits of green algae from which green plants diverged

Division Chlorophyta (green algae) Order Charales

Multicellular, chlorophylls a and b, carotenoids, starch, cellulose walls, Sporopollenin in spore walls Zygote is the only diploid cell in the life cycle

Reproductive Trends

Oogamy Heteromorphic alternation of generations Large, complex gametophyte (Bryophytes) --> smaller, simpler gametophyte (Vascular Plants) Homospory --> Heterospory

Salvinia

Produces a whorl of 3 leaves, 2 of which are chlorophyllous and undivided, and the third is divided and hangs down below the surface of the water resembling a root Normal leaves have water repellent hairs (egg beater shaped) Sporocarp with Megasporangia No true roots

Lignophytes

Progymnosperms - intermediate between seedless vascular plants and seed plants Evolution of the Ovule - Late Devonian (365 MYA) Megaphylls Over next 50 million years, many groups evolved Today - 5 phyla with living representation: Cycadophyta (Cycads); Ginkgophyta (Ginkgo); Conferophyta (Conifers); Gnetophyta; Arthophyta (Angiosperms)

Isoetes

Quillwort Modern Lycophyte Long Microphylls, all fertile, either microsporophyll or megasporophylls Distributed all around the world and are found on all continents excluding Antarctica; however, often naturally rare or uncommon in many areas All Isoetes rely heavily on an abundance of water to survive Stems have secondary growth and ligules

Botrypus

Rattlesnake Fern The tapered tip of the fertile segment is said to resemble a rattlesnake tail

Equisetum

Roots develop from horizontal rhizomes that extend along the ground Upright green stems, the major site of photosynthesis, leaves or branches at joints (horsetails) Stems jointed (Dimorphic) Whorled Branches Strobilus (Clusters of small umbrella-like sporangiophores - produce sporangia) Stems rubbed, hollow, and jointed - strengthened by silica rather than lignin - rough texture due to silica Often found in marshy habitats and along streams and sandy roadways The stems have a large air canal to allow movement of oxygen into the rhizomes and roots

Heterosporous Leptosporangiate Ferns

Salviniasceae (Free-Floating Ferns): Aquatic; Salvinia, Azolla; Heterosporous; floating fronds and submerged fronds Marsileaceae (Marsilia Water Clover): rooted with floating leaves Polypodicaceae: most common in our area; often divided into multiple families; Homosporous

Lycophytes

Seedless plants *Microphylls* (club mosses, Selaginella, quillworts)

Sorus

Sori normally develop on the abaxial (dorsal, lower side) or on the margin of the leaf The shape, arrangement, and location of the sori are often valuable clues in the identification of fern taxa

Monophyletic

The differences in life cycles among land plants can be interpreted as special reproductive adaptations as the various plant phyla diversified from the first plants

What are the key moments in plant evolution?

The transition to land Development of vascular systems Evolution of Heterospory Evolution of the Seed Diversification of the Angiosperms

Circinate Vernation

The uncoiling that the young frond undergoes to unfurl into a fully expanded leaf

Why is it believed that ancient Charophytes are land plant's oldest ancestors?

They believed they lived in shallow water that sometimes dried out (like modern Charophytes) Selection would have favored adaptations in these Charophytes to resist drying out such as waxy cuticles and protecting developing embryos within layers of tissues - these preadaptations facilitated the transition onto land The ancestor of modern plants once established on land had enormous opportunities - no competition for sunlight or minerals and no herbivores

Bryophytes

Transitional between the charophycean green algae and the vascular plants Include mosses, liverworts, and hornworts Today, about 15-23,000 species of bryophytes Habitiats range in elevation from sea level up to 5,500 m or more Only plants for the first 50-75 million years that terrestrial communities existed No true stems, leaves, or roots Sperm are biflagellate Uptake of water occurs by absorption and diffusion Typically found in most habitats Small plants, low to the ground Gametophytes may be differentiated into stem-like and leaf-like structures The gametophyte is the conspicuous phase of the life cycle Stomata on the sporangia (2n) Bryophytes of all phyla often have mycorrhiza fungi associated with their rhizoids Hornworts - symbiotic relationship with cyanobacteria; nitrogen fixation

Euphyllophytes

True Leaves *Megaphylls* *Monilophytes*: seedless plants - Pteridophytes (ferns, whisk ferns, and horsetails) *Spermatophytes*: seed plants - Lignophytes; Gymnosperms (Cycads, Ginkgo, Conifers, Vessel-containing Gymnosperms); Angiosperms: Flowering Plants

Marsilea

Water Clover The sporophyte grows in mud or submerged with leaves floating on the water surface Produces bean-shaped drought resistant stalked sporocarps The sporocarp is more elaborate structure formed from an entire leaf whose development and form is greatly modified; these are hairy short-stalked bean-shaped structure Sporocarp with chains of sori on a sporophore - each sorus contains both Megasporangia and microsporangia

Psilotum

Whisk Fern Epiphyte Dichotomously branched aerial stem Scale-like "foliar" structures (enations) Underground rhizome with rhizoids Terminal sporangia (usually in aggregates of 3) - synangium Homosporous Distributed worldwide in tropical or warm temperate regions