Nonvascular Plants Ch. 29.2 – Dec 3, 2014

NONVASCULAR PLANTS Nonvascular plants lack vascular tissue Have a “leafy” appearance but do not have true roots, stems and leaves Only have rootlike, stemlike, leaflike structures

NONVASCULAR PLANTS Gametophyte is the dominant generation in nonvascular plants i.e. the generation that we recognize as the plant Flagellate sperm swim in a continuous film of water to the vicinity of the egg Sporophyte develops from the zygote, is attached to and derives its nourishment from the gametophyte shoot

Bryophytes Life cycles of mosses and other bryophytes are dominated by the gametophyte stage Bryophytes are represented today by three phyla of small herbaceous (nonwoody) plants Liverworts, phylum Hepaticophyta Mosses, phylum Bryophyta Hornworts, phylum Anthocerophyta

Bryophytes LIVERWORTS (PHYLUM HEPATOPHYTA) Gametophore of HORNWORTS (PHYLUM ANTHOCEROPHYTA) MOSSES (PHYLUM BRYOPHYTA) Gametophore of female gametophyte Marchantia polymorpha, a “thalloid” liverwort Foot Sporangium Seta 500 µm Marchantia sporophyte (LM) Plagiochila deltoidea, a “leafy” liverwort An Anthoceros hornwort species Sporophyte Gametophyte Polytrichum commune, hairy-cap moss

Liverworts Have no true roots or shoots Require water to reproduce Have no or very little leaf structure Cannot live in sporophyte form Exists in two types Flat, lobed thallus (body) Leafy (are more numerous)

Liverworts Marchantia Smooth upper surface Lower uracea has numerous rhizoids (rootlike hairs - project into the soil) Reproduces both asexually and sexually Gemmae cups on the upper surface of the thallus contain gemmae Gemmae = group of cells that detach from the thallus and can asexually start a new plant

Liverworts Sexual reproduction depends on: Dish-headed stalks that bear antheridia (flagellated sperm are produced) Umbrella-headed stalks that bear archegonia (eggs are produced) Following fertilization, tiny sporophytes composed of a foot, short stalk and a capsule begin growing within archegonia Windblown spores are produced within the capsule

Mosses Land plant Most have no vascular tissue Majority of life spent in gametophyte Need water to breed No leaves or roots Sporophytes are capsules on stalks

Mosses Most reproduced asexually by fragmentation Gametophyte of mosses have two stages First, there are algalike protonema (branching filament of cells) After three days of favorable growing conditions, upright leafy thalli appear at intervals along the protonema.

Mosses Rhizoids anchor the thalli, which bear antheridia and archegonia Antheridium – consists of a short stalk, an outer layer of sterile cells and an inner mass of cells that become the flagellated sperm Archegonium - which looks like a vase with a long neck, has a single egg located inside its base

Mosses Dependent sporophyte consists of a: foot (grows down into the gametophyte tissue) stalk upper capsule, or sporangium (windblown spores are produced) At first, sporophyte is green and photosynthetic At maturity it is brown and nonphotosynthetic WHY? Gametophyte is the dominant generation It seems consistent for spores to be dispersal agents

Mosses

Hornworts Free-floating aquatic plant, or land plant No vascular tissue No true leaves or roots Can live in both gametophyte and sporophyte forms

Adaptations and uses of Nonvascular Plants Mosses Better at living on walls, fences and even in the shady cracks of hot, exposed rocks For these microhabitats, being small and simple seems to be a selective advantage Colonizing bare rock = help convert rocks to soil that can be used for the growth of other organisms

Adaptations and uses of Nonvascular Plants Bogs - ground is wet and acidic Dead mosses, especially Sphagnum, do not decay Accumulated moss called peat or bog moss Commercially important Can be used as fuel Nonliving cells can absorb moisture

Complete “Check Your Progress” pg. 606 #1-2 Handout