• CHAPTER XXXI. 



MORPHOLOGY OF THE ANGIOSPERMS : TRILLIUM; 

 DENTARIA. 



Exercise 60. 



316. Trillium. — Note the general habit of the plant ; the short, thick, 

 underground stem, which is perennial ; the roots attached to this ; the 

 scale leaves at the anterior end around the base of the flowering stem. Note 

 the flowering stem ; the whorl of three green leaves on it, and the terminal 

 flower. Observe that there are no roots attached to the flowering stem. Is 

 the flowering stem perennial ? 



Exercise 61. 



317. Flower of trillium. — Observe the difference in the parts of the 

 flower ; two whorls of leaf-like parts on the outside. Take these up in 

 order, beginning at the outside. 



Outer whorl (calyx) ; note the resemblance of each member of the calyx 

 to the leaf. How do they compare in number with the whorl of leaves on 

 the stem ? Sketch one. Each one is a sepal. 



318. Corol'a the second whorl. — Is there any resemblance between the 

 parts of the corolla and a leaf of trillium ? How do the parts compare as to 

 form and number with the leaves ? Sketch one. Each part of the corolla 

 is a fetal. 



319. Third and fourth whorl (andrcecium). — Note here that there are six 

 members composing these two whorls, three in each. Is there any resem- 

 blance between these and the leaves ? Did you ever see any of these mem- 

 bers (stamens) partly changed to petals or leaves in trillium? Did you ever 

 see any of them partly changed in other flowers ? in the water lily for ex- 

 ample. Examine, a water lily when you have an opportunity. Look for 

 these changes in other plants when you have an opportunity. 



Sketch a stamen, and name the parts, the slender stalk (filament), the 

 more expanded part (anther) with four long sacs (anther locules, or sacs) ; 



194 



