GENERALITIES of the PLANT KINGDOM Multicellular eukaryotes that are photosynthetic and autotrophic Most are terrestrial (some have returned to water) Plants are immobile  evolved to cope with stress: water loss, consumers, mechanical damage, temperature extremes, pathogens, odd soils, etc. Terrestrial plants evolved from aquatic green algae

Features Shared In Common with Green Algae Pigments: Chlorophyll a & b; carotenoids Food Reserve: Starch Cell Walls: Cellulose Cell Division: Cell Plate Body Structure: Multicellular Life Cycle: Heteromorphic Alternation of Generation Sexual Reproduction: Oogamy

Bryophytes Pteridophytes Division Chlorophyta (green algae) Order Charales features: multicellular, chlorophyll a, b, and carotenoids, starch storage, cellulose walls

In Aquatic Habitat All Cells Surrounded or Close to Water Dissolved Minerals Dissolved CO2 and O2 Water Supports Weight of the Plant Unicellular Reproductive Structures Motile Gametes All Cells Photosynthetic

Evolutionary steps for the colonization of land: How to disperse gametes in drier environment How to protect embryos from drying out How to take up water and nutrients from below ground How to take up CO2 from the air How to transport water and nutrients long distances

Adaptations to Land Correlated with Development of Structures to Circumvent Water Requirements: Epidermis: cuticle (cutin), stomates Vascular Tissue: Xylem (water conduction), Phloem (carbohydrate conduction) Roots Lignin - found in all vascular plants, reinforces cell walls Multicellular gametangia: Antheridium (sperm), Archegonium (egg) Embryo Develops Within the Archegonium

Pangaea (meaning "all lands" in Greek)

Silurian land plants (425 - 408 MYA)

Devonian land plants (408 - 362 MYA)

Carboniferous land plants (362 - 290 MYA)

Permian land plants (290 - 245 MYA) The warm zone spread in the northern hemisphere, where extensive dry deserts appeared. The rocks formed at that time were stained red by iron oxides, the result of intense heating by the sun of a surface devoid of vegetation cover. The old types of plants and animals died out.

Triassic land plants (245 - 208 MYA)

Jurassic land plants (245 - 208 MYA)

Sporophyte (2n) Ca. 0.5 cm long Gametophyte (1n)

Bryophytes Mosses, liverworts and hornworts Reproduce by spores Reproduction dependent on water No true vascular system, no hard tissues, therefore they remain small

Vascular Plants (all the rest = ferns, gymnosperms & angiosperms) Have true roots, leaves, & vascular tissues Produce hard or lignified tissues xylem phloem

Seedless Vascular Plants: Ferns & allies Have vascular tissue & true roots Reproduction depends on water Reproduce w/ spores

Evolution of seed plants: Gymnosperms & Angiosperms Reproduction independent of water Sperm enclosed in pollen; dispersed by wind, animals, etc Eggs enclosed in protective ovule – matures into a seed Seeds are highly protected embryos - embryo protected (cones, fruits, etc) - often specialized dispersal (animal, water, wind) - Woody tissues common

Gymnosperms‘Naked seed’ Old lineage; 700 species today Adaptive radiation during Earth’s dry periods New invention true seeds! protects embryo Conifers are largest group - make male & female cones

Most recently derived group - 300,000 - 450,000 species eudicots Angiosperms Most recently derived group - 300,000 - 450,000 species Two main groups: 1. eudicots 2. monocots New Innovations: Flowers Fruit monocots

Angiosperms monocots eudicots Almost all angiosperms fall naturally into two groups (clades), monocots (one cotyledon, or seed leaf) and dicots (two cotyledons). A few dicots (early lineages) do not form a clade, but the huge majority that do are called true dicots, or eudicots.