7 Without water, strategies for dipersal of sex cells needed to be developed Sex cells and zygote needed a means of dispersal that was independent of water.Protective structures were required to protect the developing embryos.The above were achieved with the origin of the seed plants.
8 Characteristics Nonvascular Lack true roots, leaves and stems Rootlike structure s are called rhizoidsRely on diffusion and poorly developed conducting tissues to distribute water and nutrients.Enclosed reproductive structuresArchegoniaAntheridia
22 PTEROPHYTA True ferns Broad leaves called fronds Leaflets called pinnaeSporangium (sorus pl sori) are formed on the underside of the fronds.Unfolding fronds are called fiddleheads.Spores are dispersed by the wind.
30 Ginkophyta Only one species in present day. Ginkgo biloba Are resistant to air pollutionBear male and female cones on separate plants.Male produces pollen in strobilus-like cones.Female bears seed which develop a fleshy outer covering and resemble orange-yellow cherries. (Stinks!)
32 CONIFEROPHYTA Cone-bearing trees Most diverse of the gymnosperms: produce seeds in woody cones. Include pine, fir, spruce, juniper, cedar, redwood, yew, and larch.Form large forests and have adapted to cold and dry habitat (taiga).Protected against water loss by leaves covered with a thick cuticle (cutin) and by covering it’s trunk and branches with bark.Conifers are evergreensThey do loose their leaves if aged or damaged.Keeping leaves allows photosynthesis to begin at the earliest moment in spring.Found where nutrients are scarce as they eliminate need to grow a whole new set of leaves (Deciduous trees lose their leaves).
37 GNETOPHYTACan be found in the deserts or mountains of Asia, Africa and central or South America.3 genera1. Gnetum : A tropical climbing plant2. Ephedra (Shrub-like plants and found in U. S.)i. “Mormon tea” Scrubby cone-bearing plant with scale-like leaves.a. Source of ephedrine: used to treat asthma, emphysema, and hayfever.3. Welwitschia (Desert dweller with large tuberous root)i. Has only 2 leaves and may live 100 yr.