Bryophytes 2 and Intro to Vascular Plants

3 main classes of Phylum Bryophytes

1) Sphagnidae (Peat mosses)

2) Andreaeiidue (granite mosses)

3) Bryidae (true mosses)

Sphagnum: class sphagnidae (Characterisitcs)

• Stalk (pseudopodium)(gametophytic tissue)

• Sporophyte has a short seta

• Capsule of Sporahgium has a lid-like operculum.

• Explosive discharge as the capsule dries.

Sphagnum (cell types)

1) Large deal cells (hyaline cells)

2) Narrow green living cells around hyaline cells

Sphagnum (Uses)

Absorptive, antiseptic, soil conditioning (horticulture), wound dressing, dispers, sanitary napkins.

Granite Mosses (what class)

Class Andreaeidue

Grantic Mosses (Tufted mosses)

• Often found on rocks/mountainous/arctic habitats

Unique spore discharge: slits in capsula

True Mosses (class)

Class Bryidae

True Mosses (characterized)

• Protonema (single row of cells)

• Leafy gametophytes develop buds on protonema

• Multicellular Rhizoids

• Leaves: 1 cell layer thin

True Mosses (Specialized tissues for water/food cells)

• Hydroid - Water conducting cells; dead (empty) at maturity.

• Leptoids - Food conducting cells; living (protoplast), no nuclei.

True Mosses (sporophytes, gametophytes and sporangia)

• Matrotrophic sporephytes

• Gametophtes lefty (Antheridia often clastered with leafy structures (splash cups)

• Some sporanggia brightly coloured (seta can reach 15-20cm)(sporophyte: photosynthetic with stomata)

Spore Dispersal

• Calyptral: Derived from archegonium

• Peristome Teeth: Under operculum

• Teeth uncurl as they dry, exposing spores

Evolution of vascular plants

Vascular plants: sporophytes are more prominent than gametophytes, where gametophytes have a reduced size, are more protected, and nutritionally dependent on the sporophyte.

Vascule Plants (adaptations)

Fluid-conduction system (xylem and phloem)

• Lignin in cell walls (rigidity and support for taller plants)

• More specialized differentiated plant body (root, stems, and leaves).

• Dermal, vascular tissue systems

Tracheids

• Only water-conducting cells in most vascular plants (except angiosperms)

• Channels for water and minerals

• Also provide support (lignified cell walls)

Vascular cylinders (stele)

• Protostele (simplest/most ancient)

• Siphonostete (most seedless vascular plants)

• Eustele (almost all seed plants)

Microphylls

Relatively small istrand of vascular tissue

• Associated with protostele

• NO leaf gap

Magephylls

Blade (laminate) with complex system of veins

• Associated with siphonostele (with leaf gap) and eustele.

• Evolutionary transformation (overtopping, planation, webbing)

Vascular Plants (life cycle)

Alternation of heteromorphic generations (sporophyte is larger and more complexed)

Homosporous

One kind of spore as result of meiosis

• Each spore produces bisexual gametophytes

• Almost all ferns, horsetails, come from the lycophytes

Heterosporous

2 types of spores in 2 kinds of sporangia

• Microspores (in microsporangia) and magaspores (in megasporangia)

• Some lycophytes, a few ferns, and all seed plants

Early Vascular plants

Middle silurianted middle Devonian (425-370mya)

Seedless vascular plants (extinct and extant)

• Exinct: Rhyniophyta, Zosterophyllophyta, Trimerophyta

• Lycopodiophyte, Monilophyta

Seed plants (include)

• Gynosperm (290 mya) (permian-mesozoic)

• Flowering plants (135 mya) (Dominant ever since)