59 . 



Many plants seem to have no protection Imt grow in positions 

 where they can he away from danger ; others seem to grow utterly 

 unprotected. 



2 . Protect inr\ during transition . 



B^^ds — hy scales, hairs and position in hud. At this time 

 (transition) we find also greatest developiiient of color.. Leaf 

 movements. Development of seedlings. Seedcoats, movements, 

 hendings of stems, scales, hairs, etc. 



3.^ Protection dulring rest period . 



This is highest development. Crisis in life a tree, usually 

 the season of winter. Duckweed — large cells or air spaces which 

 serve not only for storage of air hut also for purposes of buoyancy. 

 In fall a hud comes out without the cells and falls to the bottom 

 ?/here it remains during the cold season. 



Annuals.. Perennials. On land have various ways of protection, 



Rosette form during period of rest and erect stem during period of 



vegetation. Corns, bulbs, tubers, rhi^oids. Trees themselves 

 with deciduous leaves. Evergreens. 



Why is a tree "? 



Question of erectness — a necessity of light, 



Question of woody stem — duration and economy. 



No form better adapted to extreme xerophytic conditions than a 



certain modification of the tree type, the barrel-shaped tree with 



immense development of storage tissue. Yuccas on our westerii deserts. 

 First trees were Pteridopljytes and Gymnospenas. 



