CHAPTER XXXIII. 



MORPHOLOGY OF THE ANGIOSPERMS: TRILLIUM; 

 DENTARIA. 



Trillium. 



440. General appearance. — As one of the plants to illustrate 

 this group we may take the wake-robin, as it is sometimes called, 

 or trillium. There are several species of this genus in the 

 United States ; the commonest one in the eastern part is the 

 "white wake-robin" (Trillium grandiflorum). This occurs in 

 or near the woods. A picture of the plant is shown in fig. 290. 

 There is a thick, fleshy, underground stem, or rhizome as it is 

 usually called. This rhizome is perennial, and is marked by 

 ridges and scars. The roots are quite stout and possess coarse 

 wrinkles. From the growing end of the rhizome each year the 

 leafy, flowering stem arises. This is 20—^ocm (8—12 inches) in 

 height. Near the upper end is a whorl of three ovate leaves, 

 and from the center of this rosette rises the flower stalk, bearing 

 the flower at its summit. 



441. Parts of the flower. Calyx. — Now if we examine 

 the flower we see that there are several leaf-like structures. 

 These are arranged also in threes just as are the leaves. First 

 there is a whorl of three, pointed, lanceolate, green, leaf-like 

 members, which make up the calyx in the higher plants, and the 

 parts of the calyx are sepals, that is, each leaf-like member is a 

 sepal. But while the sepals are part of the flower, so called, we 

 easily recognize them as belonging to the leaf series. 



