Plant Diversity I: How Plants Colonized Land AP Biology Crosby High School

Evolutionary Adaptations Evolutionary AdaptationsBryophytes: –Mosses –Lack vascular tissue Pteridophytes –Ferns –Seedless plants Gymnosperms: Naked seed Angiosperm: Flowering plants

Charophyceans Most related green algae Similarities –Rosette cellulose-synthesizing complexes –Peroxisomes Minimize loss of organic product during photorespiration –Phragmoplasts Alignment of cytoskeletal elements and golgi derived vesicles

Terrestrial Plant Adaptations Apical Meristems Apical Meristems Multicellular, dependent embryos Alternation of Generations Alternation of Generations Walled Spores Produced in Sporangia –Sporopollenin: durability –Sporangia Multicellular Gametangia –Archegonia –Antheridia

Other Terrestrial Adaptations Water Conservation –Cuticle: polyesters and waxes –Stomata: gas exchange Water Transport (except Bryophytes) –Xylem: water and nutrients –Phloem: sugar, a.a. and other organic product Secondary Compounds

Land Plants Evolved from Charophyceans 500 mya Homologous chloroplasts Homologous peroxisomes Phragmoplasts Homologous sperm Homologous Cellulose walls (20-26% cellulose) Molecular comparison

Bryophytes Phylum Hepatophyta: liverworts Phylum Anthocerophyta: hornworts Phylum Bryophyta: mosses

Gametophyte Dominant generation Moss produce green, branched one-cell- thick filaments (protonema) Few cells thick and few cm tall Anchored by rhizoids Lack cuticle Separate male and female

Sporophyte Sporophyte attached to gametophyte Liverworts: tiny body, short stalk w/ sporangia w/ protective epidermis MossMoss: Moss –Foot –Septa –Sporangium (capsule)

Pteridophytes Vascular systems –Microphylls –Macrophylls Sporophyte dominant lifecycle –Homosporous –Heterosporous MegasporesMicrospores

Phylum Lycophyta Epiphytes: use other organisms as substratum, but are not parasitic Some close to ground Upright stems w/ many microphylls Sporophylls: bear sporangia that release flammable spores

Phylum Pterophyta Psilophytes –Psilotum: Whisk Fern –Dichotomous branching and lack of true leaves and roots Sphenophytes –Marshes, streams or sandy roadsides –Upright and horizontal stems (rhizomes)

Phylum Pterophyta Ferns –Horizontal rhizomes grow leaves w/ extensively branched vascular system –Leaves called fronds and divided into many leaflets –Produce clusters of sporangia (Sori) Patterns help identify ferns Sporangia have spring-like structures to catapult spores

Ferns

Fern Life Cycle Fern Life Cycle

Bryophytes

Moss Life cycle Moss Life cycle

Alternation of Generations

Apical Meristems

Plant Evolution