Continuing Trends in Plant Evolution Reduction of water-dependent gametophyte Vascular tissue – improved water/food transport More efficient roots, stems, leaves *Tissues *Stomates Green: all these are in sporophyte

Reduction of gametophyte Specialization in sporophyte

Vascular tissue In sporophyte Interconnects all plant organs Xylem - water Phloem - sugar

Complex leaves Tissues Stomates

Plant classification review Bryophytes – no seeds, no roots, no vascular *Mosses, liverworts, hornworts Seedless, vascular plants – no seeds *Ferns, horsetails, club mosses, whisk ferns Gymnosperms - seeds & cones *Conifers, cycads, ginkgo, gnetophytes Flowering plants – seeds, flowers & fruits *Primitive, Monocots, Dicots

Seedless Vascular Plants Ferns, horsetails, club mosses, whisk ferns Sporophyte dominant Gametophyte small but still tied to water Dominant plants from late Devonian through early Permian *Equatorial coal forests Today somewhat marginal, but successful Heterospory in some (next time)

Fern Life Cycle Gametophyte Fertilization Sporophyte Meiosis

Fern gametophytes … … with young sporophytes Mature fern sporophyte … … with clusters of sporangia

Whisk Fern, Psilotum

Club moss, Lycopodium

Horsetail, Equisetum

Carboniferous (-300 my) coal forest model