Plants, Fungi and the Move Onto Land

Colonizing Land Terrestrial Adaptations? Structural Shoots, roots, leaves Vascular tissue

Colonizing Land Terrestrial Adaptations Reproductive Gametangia Embryophytes: egg is fertilized and develops within plant Plants are heteromorphic: sporophyte and gametophyte

Charophytes and Plants Green algae (seaweeds) are most probable plant ancestor 475 million ya, shallow seas experiences seasonal droughts Natural selection would favor gametangia formation

Plant Highlights

Bryophytes Non-vascular (mostly) (no xylem & phloem) Swimming sperm Waxy cuticle Embryo develops inside female gametangia Zygote develops into sporophyte

Ferns Evolution of vascular tissue Swimming sperm Seedless plants Use spores for dispersal strategy

Carboniferous period (300 mya)

Evolution of the Seed Independence on water for reproduction Climate became drier and colder Utilize air and insects for pollen Three main groups: seed ferns, gymnosperms, and angiosperms Produce microspores (pollen) and megaspores (ovule) Seed is a fertilized ovule (embryo)

Mosses, Ferns and Seed Plants

Gymnosperms: “naked seeds” Unprotected seeds Include: conifers, cycads, ginkgos, and gnetophytes Independent of water for fertilization

Gymnosperms Cone-bearers Woody trees with needle-like or scale- like leaves Evergreen and deciduous

Angiosperms Only plants with true flowers Seed is enclosed in an ovary Coevolution with pollinators

Most successful and diverse group

Angiosperms

Angiosperm Pollinators

Seed Dispersal

Values of Plant Diversity

Kingdom Fungi Decomposers of dead organics (saprobes) Help recycle nutrients 430 million years of evolution on land Over 80,000 species classified

Kingdom Fungi Heterotrophs: feed by absorption Extracellular enzyme secretion Most are multicellular

Typical Fungi Life Cycle

Kingdom Fungi – Lichens Mistaken as mosses Mycobiont is usually an ascomycete Photobiont can be a chlorophyte and/or cyanobacterium When both, cyano’s primarily fix nitrogen

Kingdom Fungi – Mycorrhizae Hyphae increase surface absorptive area Plants receive nutrients and water from fungus Fungi receives carbohydrates from plant Many plants are dependent

Ecological Impacts of Fungi Parasites Commercial use