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 Divison Hepatophyta: Liverworts

• Sporophyte

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 Division Anthocerotophyta: Hornworts

– Sporophyte