seedless vascular plants

genus azolla

(mosquito fern, duckweed fern, fairy moss, water fern) a genus of seven species of aquatic ferns in the family Salviniaceae. They are extremely reduced in form and specialized, looking nothing like conventional ferns but more resembling duckweed or some mosses. The nitrogen-fixing capability of Azolla has led to Azolla being widely used as a biofertilizer, especially in parts of southeast Asia. It has been used to bolster agricultural productivity in China for over a thousand years. When rice paddies are flooded in the spring, they can be inoculated with Azolla, which then quickly multiplies to cover the water, suppressing weeds. The Azolla contain a nitrogen-fixing cyanobacterial symbiont.

epiphytic habit

1/3 of species are epiphytic (i.e. they grow on other plants, generally trees)

fern characteristics (monilophyta)

11,000 species Largest group of plants other than flowering plants (angiosperms) Greatest diversity of ferns found in tropics Mostly homosporous (except water ferns) There are two types of sporangia within the ferns Euporangia Leptosporangia

Order Salviniales (Water ferns)

2 families Marsileaceae Salviniaceae (Genus Salvinia , Genus Azolla)

rhizome

A horizontal, underground stem that produces new leaves, shoots, and roots

megasporangium

A plant structure in which megaspores are formed, such as those of the female cones of pines.

spore

A reproductive cell with a hard, protective coating

bryophytes and vascular plants: similarities

Both have: a multicellular embryo alternation of heteromorphic generations (sporic meiosis)

plant tissue layers

Dermal system (epidermal cells on outside ) vs ground tissue system (cortex) includes the parenchyma Parenchyma cells- your everyday plant cells that are not reallly specialized Then at center we have the stele

prothallus

Gametophyte has the form of a flat, heart-shaped structure numerous rhizoids on lower surface Antheridia and archegonia develop on the ventral (lower) surface of the prothallus-They may mature at the same time or separate time - promoting either self-fertilization or cross-fertilization

leaf trace

In ferns, a region of parenchyma tissue above the point of departure of a leaf trace part of the vascular cylinder that extends to the base of a leaf

genus salvinia

Leaves borne in whorls of three on a floating rhizome One of the three hangs down into the water is highly dissected - looks like roots but is really a leaf This rooty leaf also bears the sporangia

genus psilotum

Mainly tropical and subtropical We have these in SC VERY simple structure - a derived condition No true leaves: Dichotomously branching stems and small scale-like "foliage" Sporangia are present in groups of three on the ends of short lateral branches

spikemoss male gametophyte

Male gametophytes develop entirely within the microspore and have no chlorophyll - here we can see the gametophyte generation has been very much reduced. At maturity the male gametophyte consists of one vegetative cell + an antheridium; the the spore wall ruptures, the sperm are liberated and swim away

Isoetes (quillworts)

One genus: Isoetes Found in wet habitats or places that are periodically wet Short fleshy underground stem (corm) with quill-like microphylls on upper surface and roots on lower surface Closest living relative of the extinct tree lycophytes of the Carboniferous period Heterosporous: Megasporangia on megasporophylls, microsporangia on mirophylls Note presence of ligules Not absence of strobili

Selaginella (spike mosses)

Only one extant genus: Selaginella. About 750 species, mostly tropical have ligules heterosporous, unisexual gametes the gametophyte generations will stay contained within the spores. The sporophyte will grow from the zygote, which is embedded in the female gametophyte, which is still encased in the megaspore wall. have 2 types of sporophylls: mega and microsporophyll

monilophyta classes

Psilotopsida (Eusporangiate Ferns) Marattiopsida (Eusporangiate Ferns) Polypodiopsida (mainly Leptosporangiate ferns) Equisetopsida (Horsetails)

Class Equisetopsida (Horsetails)

Single genus: Equisetum homosporus Moist habitats Conspicuously jointed stems with ribbed internodes Whorls of small scale-like leaves Leaves are microphylls, but this is a derived character Stems arise from branching underground rhizomes Hollow stems with eustele-like architecture Sporangia are borne in groups of 5-10 on sporangiophores, clustered into strobili at the stem apex

indusium

Specialized leaf outgrowth that covers the young sori Umbrella-like shape Often but not always present Often shrivels when sporangia are mature

leptospoangium (leptosporangiate sporangia)

Sporangium that arises from a single initial cell and whose wall is composed of a single layer of cells fern-specific thing. You find them in ferns of the class Polypodiopsida. First division produces an outer and inner cell. Further divisions produce a stalk and a capsule. As the sporangium dries out, contraction of the annulus causes tearing in the middle of the capsule. The sudden explosion and snapping back of the annulus to its original position results in a catapult-like discharge of spores.

eusporangium (eusporangiate sporangia)

Sporangium that arises from several initial cells and, before maturation, forms a wall with more than one layer of cells characteristic of all vascular plants EXCEPT the leptosporangiate ferns.

Trends in vascular plant evolution

Stele Leaves Heterospory Dominant sporophyte

spikemoss female gametophyte

The female gametophyte also develops within the spore wall - as it matures, the spore wall ruptures and the gametophyte protrudes out Archegonia are present, but in most cases there is no chlorophyll and the gametophyte depends entirely for nutrition on food stored in the megaspore. Water is required for fertilization. Note the formation of a suspensor during embryo (young sporophytedevelopment - this structure will also appear in other plants later in the course. Eventually the yound sporophyte grows up out of the old megaspore covering.

bryophytes and vascular plants: differences

Vascular plants only: Sporophyte dominant True xylem and phloem Lignin Apical meristems at stem tips of sporophyte Apical meristems can branch (as opposed to the hornwort which had one sporophyte with one one sporagium and one apical merisstem from which it grows) More sporangia per sporophyte Specialized roots and shoots microphyll: first specialized leaf

functionally unisexual

a bisexual gametophyte in which the sperm from the antheridia do not often fertilize eggs from the archegonia of the same plant, resulting in little self-fertilization

sorus

a cluster of leptosporangia

synangium

a compound sorus made up of united sporangia

spore mother cell

a diploid cell that undergoes meiosis to form 4 haploid cells

sporangium

a hollow structure in which spores are produced

microsporangium

a plant structure that produces microspores

microphyll leaf

a small leaf with one vein and one leaf trace found in lycophytes not associated with a leaf gap Probably evolved as superficial stem outgrowths (enations) that later became vascularized

genus ophioglossum

adder's tongue vegetative portion of the leaf is undivided Fertile segment of leaf is undivided and has two rows of sunken eusporangia

rhizoid

any of various slender filaments that function as roots in mosses and ferns and fungi etc

fertile frond

carries sporangia; capable of reproduction

stele

central cylinder of a root or a stem that contains the vascular tissue (xylem and phloem) may also contain pith

Lycopodiaceae (club mosses)

commonly called fern allies All but two genera of living lycophytes belong to this family. Most are tropical. Sporophytes = branching rhizome from which microphylls and roots arise Microphylls usually spirally arranged Roots and stems have protostele Homosporous Gametophytes bisexual Sporangia occur singly on upper surface of special microphylls called sporophylls In some cases sporophylls are separate from other leaves -grouped into strobili at the ends of the branches gametophyte is sometimes nonphotosynthetic, mycorrhizal, and stays belowground. in others it's an irregular, lobed green mass

strobilus

cone which nonphotophynthetic sporophylls are often grouped into (cluster of sporophylls at end of upright stalk)

endosporal germination

development of micro and mega gametophytes begins within the spore wall

sterile frond

does not carry sporangia; incapable of reproduction

tracheid

elongated xylem cell with closed, tapering ends; present in seedless vascular plants and seed plants; transport and rigidity pits allow water to flow from one to the other up the plant

sieve cell

elongated, slender phloem cell with tapering ends Also has pits where the sugar water can move

class Psilotopsida

eusporangiate ferns Two orders: Ophioglossales [Genus Botrychium (grape ferns) and Genus Ophioglossum (adder's tongue)] Psilotales [Genus Psilotum (whisk fern) and Genus Tmesipteris ] -All these guys have bisexual subterranean gameotophytes with mycorrhizal fungi -in both genera (of ophioglossales?), a single leaf is produced each year

exosporal germination

gametophytes develop outside the spore wall

Genus Botrychium

grape fern vegetative portion of the leaf is very dissected Fertile segment of leaf is divided and has two rows of eusporangia on its outer segments

siphonostele

has a central pith surrounded by vascular tissue This is the stele type found in most seedless vascular plants The phloem may be found outside the xylem cylinder or on both sides of it can be with or without leaf gaps

megaphyll leaf

larger leaf with several to many veins found in ferns, horsetails and higher plants leaf trace associated with a leaf gap/leaf trace gap Evolved independently three separate times in three different plant lineages (ferns, horsetails, seed plants).

class Marattiopsida

largest fronds of any known fern Circinate = ring-shaped Vernation = arrangement of young leaves Shape protects the delicate embryonic leaf tip during development More rapid growth on the inner than the outer surface of the leaf causes the "unfurling"

homosporous seedless vascular plants

lycopodia (club mosses) all monilophyta

class polypodiopsida

mainly Leptosporangiate Most ferns (> 10,000) belong to this class Almost all homosporous-Exception is the heterosporous water ferns Siphonostele rhizome that produces new batch of leaves each year Large megaphylls (fronds) Leptosporangia generally on margins or lower surface of leaves Sori (sorus) and indusia (indusium) Free-living gametophyte (prothallus)

homosporous plants (homosporous sporophyte)

make one type of spore Spore produces bisexual gametophytes The gametophytes have both archegonia and antheridia This is the ancestral state - heterospory evolved later (several times)

heterosporous plants (heterosporous sporophyte)

make two types of spores Spores produce unisexual gametophytes MICROspores =male gametophytes MEGAspores =female gametophytes Arose independently several times in seedless vascular plants and seed plants

bisexual gametophyte

makes both sperm and eggs

unisexual gametophyte

makes either sperm or eggs

sporophylls

modified leaves that bear the SPORANGIA.

sexually dimorphic

phenotypic difference between males and females of the same species

Seeded vascular plants only (Gymnosperms and Angiosperms):

presence of a Seed

circinate vernation

ring-shaped arrangement of young leaves Shape protects the delicate embryonic leaf tip during development

heterosporous seedless vascular plants

sellaginella (spike moss) isoetes (quill worts)

sporangiophore

small umbrella-like branches in which homosporous sporangia are borne in clusters of 5-10 The sporangiophores are clustered into strobili

ligules

small, scale-like outgrowth near the base of the upper surface of each microphyll

protostele

solid cylinder of vascular tissue found in primitive plants found in the stems of lycophytes and in most plant roots. contains no pith

seed

structure that provides nutrition and protection for the embryonic sporophyte

tracheary elements

the general term for lignified xylem cells in vascular plants; includes tracheids and (in angiosperms) vessel elements

sieve elements

the general term for phloem cells in vascular plants; includes sieve cells and sieve tube elements (angiosperms only)

parenchyma cell

thin walled plant cell of variable size and form; "general cell"