Nonseed Vascular PlantsSeedless Plants Seedless Vascular plants n

Non-seed Vascular Plants(Seedless Plants)

Seedless Vascular plants n Two groups recognized: n Lycophyta- club mosses n Pteridophyta- Ferns and fern allies (fern relatives)

Non-seed vascular plants n Photosynthetic vascular plants n About 12000 living species n Occur in tropical, temperate & arid regions n Underground creeping stem n rhizome. n Leaves may be divided into small leaflets called pinnae

Non-seed vascular plants… • Have clear alternation of generations • The Sporophyte: Ø Dominant generation Ø Dependent on gametophyte during early stages of life Ø consists of true roots, stems & leaves; all with vascular tissue Ø Leaves have cuticle & stomata Ø

Non-seed vascular plants… Ø Vascular tissue arranged in various types of stele Ø Spores produced by meiosis in sporangia - Sporangia found on leaves, stems, or on modified leaf-like structures called sporophylls Ø Sporangia may occur in small clusters/groups called sori (sorus)

Non-seed vascular plants… n Plants may be homosporous or heterosporous Ø Ø Ø Homosporous – produce one type (same size) of spores Heterosporous – produce two types of spores (different sizes) Microspores(small) Ø Ø Ø give rise to male prothalli (gametophyte) Produce antheridia megaspores (large) Ø Ø give rise to female prothalli (gametophytes) produce archegonia Dry conditions needed for spore dispersal

Non-seed vascular plants… n Gametophyte: Ø very reduced, called prothallus Ø Not well adapted to life on land - it is a small flat plate of photosynthetic cells with no cuticle to prevent drying out

Non-seed vascular plants… n Sexual reproduction: n oogamous Ø egg is stationary – remains in archegonium Ø Sperms(spermatozoids) swim to egg by chemotaxis to effect fertilization Ø Free water is still necessary for sexual reproduction