CHAPTER XXXI. 



MORPHOLOGY OF THE ANGIOSPERMS : TRILLIUM; 

 DENTARIA. 



Exercise 6O. 



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. Corolla the second whorl. Is there any resemblartfc 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 petal. 



319. Third and fourth whorl (androecium). 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 



