490 



PKACTICAL BOTANY 



The various strata or stories of vegetation in a forest are 

 usually arranged somewhat in the order of their light require- 

 ments, the plants most tolerant of shade at the bottom and 

 the most intolerant species at the top. Thus in an open 

 forest composed mainly of white pines mixed with a few 



other conifers and some 



deciduous trees, in New 

 England, we may find some 

 such assemblage as this: 

 close to the ground vari- 

 ous species of mosses, the 

 most conspicuous being the 

 pigeon-wheat moss (Polyt- 

 richum). Rising but little 

 above the mosses are one 

 or two species of " ground 

 pine," or "Christmas ever- 

 green" (Lycopodium, Fig. 

 245). Mingled with these 

 are many herbaceous spe- 

 cies, or very small under-, 

 shrubs representing the 



seed plants, all shade-loving 

 FIG. 369. An air plant ( TWandsia) of the . guch M rattlesnake 



Pineapple family , 



plantain, 1 " wild lily of the 



Living as an epiphyte, but having numerous r i i 



roots, it is intermediate in habit between valley, 2 chickweed, Wlll- 



the common pineapple (Fig. 283), which ter g reen 3 common wood 

 grows rooted in the earth, and the Spanish & . . 9 . 



moss (Fig. 368), which is rootless and hangs SOrrel, 4 prince S pine, Shin- 



suspended from the bark of trees. Photo- | ea f 6 partridge berrv, 7 and 

 graph by Robert Cameron ^ Q * .< 



rattlesnake-weed. 8 Above 



these, if the woods are young, grow such larger shrubs and 

 small trees as Juneberry, 9 blueberry, 10 and gray birch. 11 Mixed 

 with these are young spruces and perhaps hemlocks. Only 



1 Goody era. 2 Maianihemum. 8 Trientalis. 4 Oxalis Acetosella. 



6 Chimaphila. 6 Pyrola. 7 Mitchella. 8 Hieracium. 9 Amelanchier. 



10 Vaccinium vacillans. ll Betula populifolia- 



