Nonvascular Plants Believed to have evolved from green-algae Chlorophylls a & b and cartenoids Store starch within chloroplasts Cell wall made up mostly of cellulose Major adaptations in going from water to land A protective sterile jacket to protect reproductive structures, antheridia and archegonia Development of a waxy cuticle Development of stomata for gas exchange on sporophytes
Nonvascular Plants Classification three major divisions grouped together because of several similarities Gametophyte nutritionally independent from the sporophyte, but the sporophyte is permanently attached to the gametophyte The gametophyte is the the conspicuous generation Possess rhizoids for anchoring but not absorption Sperm requires water to swim to the egg Possess a venter (surrounds the egg), neck canal cells that disintegrate and form a tube for sperm to follow to fertilize the egg
Nonvascular Plants Antheridium surrounded by a one cell layer thick sterile jacket Spermatogenous cells form biflagellated sperm Zygote developes within the archegonium Archegonium expands to form a calyptra
Division Bryophyta: Mosses Gametophyte Generation Leafy, upright, leaves arranged in a spiral fashion Possess multicellular rhizoids for anchoring Leaves, gametophores, usually one cell thick not true leaves nor ancestors of true leaves
Division Bryophyta: Mosses Stems Very little in the way of differentiation possess a central area of conducting cells composed of hydroids and leptoids hydroids tracheid like cells, dead, empty, carry water and nutrients leptoids like sieve tubes, transport sugars, lack nuclei, many plasmodesmata Antheridia frequently found in splash cups Gametes are produced either in leaf axils or at the tips
Division Bryophyta: Mosses Sporophyte Can take up 6 18 months to develop Associated with the gametophyte Sporangia typically associated with a stalk, seta Possess stomates with only one guard cell When young are photosynthetic but lose this
Division Bryophyta: Mosses Spore dispersal Calyptra (archegonial tissue) dies, dries, and falls off, taking with it the operculum Loss of opercululum exposes the periostome, which change shape depending upon humidity, gradually releasing spores Each capsule up to 50 million spores
Division Bryophyta: Mosses Metabolism and Ecology Very prone to desiccation several adaptations have evolved to accommodate for this Grow in very moist habitats or dry areas with microhabitats, no need for vascular tissues Can become dormant during dry spells Frequently grow in dense clumps to trap moisture Some can thrive at very low temperatures Can grow on very hard, dense surfaces, not roots Play a role in soil production because of acids produced
Divison Hepatophyta: Liverworts 8500 species Diverse Inconspicuous, but may form large mats Some consider them the simplest of the plants because they have: Conducting tissue A cuticle Stomates In most the gametophyte is formed by the germination of a spore Divided into two groups
Divison Hepatophyta: Liverworts Thallose Liverworts Moist, cool, shaded environments Thallus multicellular with upper cells containing chlorophyll, lower cells colorless Upper surface lacks stomates but does have pores Marchantia very common Dichotomously branching gametophyte Gametangia located on gametophores Gametophytes are unisexual, easily seen
Divison Hepatophyta: Liverworts Gametophyte Generation Spore germinates into a small proonematal structure Small rhizoids on undersurface Can be either uni or bisexual (Marchantia unisexual)» Male - Antheridiophores
Divison Hepatophyta: Liverworts» Female - archegoniophores
Sporophyte Divison Hepatophyta: Liverworts
Divison Hepatophyta: Liverworts Leafy Liverworts About 6000 species Found in tropics and subtropics (warm and wet) Branched forms form mats Leaves only one cell thick, usually forming two rows on each side and one colorless one on underside
Division Anthocerotophyta: Hornworts Small group, only 6 genera Most common genus, Anthoceros Only one chloroplast Each chloroplast has a pyrenoid Gametophyte appears as a rosette Multicellular with mucilage between cells Within this mucilage can be found the cyanobacteria, Nostoc, which is nitrogen fixing Can be bi or unisexual Archegonia found sunken on the dorsal surface Antheridia clustered within chambers
Division Anthocerotophyta: Hornworts
Sporophyte Division Anthocerotophyta: Hornworts