270 



PLANT FAMILIES: DICOTYLEDON'S. 



Fig. 232. 

 Corolla of pea. J>. stand- 

 ard ; IV, wings ; A", two 

 petals forming keel. 



of the five petals. The petals have received distinct names here 

 because of the position and form in the flower. At fig. 232 the 

 petals are separated and shown in their corresponding positions, 

 and the names are there given. The flower 

 is irregular and the parts are in fives, except 

 the carpel, which is single. The calyx is 

 gamosepalous (coherent), the corolla poly- 

 petalous (distinct). The ten stamens are 

 in two groups, one separate stamen and 

 nine united; they are thus diadelphous 

 (two brotherhoods). The fruit forms a pod 

 or legume, and at maturity splits along 

 both edges. 



There are three families in the legume- 

 bearing plants : 1st, including the locusts, 

 cassias, etc. ; 2d, the pea family, including peas, beans, clovers, 

 ground-nuts, or peanuts, vetches, desmodium, etc. ; 3d, in- 

 cluding the sensitive plants like mimosa. 



Exercise 78. 



433. The pea (Pisum sativum). 



The entire plant. — Describe the entire plant, the branching, the means for 

 support (compare different cultivated varieties in respect to size, habit, and 

 means for support if practicable). 



The leaf. — Sketch a leaf; name the different parts; what kind of a leaf 

 is it ? Does the leaf serve any purpose for the mechanical support of the 

 plant ? How ? 



The inflorescence. — What is the kind of inflorescence ? 



The flower. — Is it regular or irregular ? 



The calyx. — Describe the calyx. How many sepals are indicated? Are 

 the sepals distinct or coherent ? What name is applied to this kind of a calyx ? 



The corolla. —What are the relations of the petals to each other? What 

 term is applied to indicate this relation ? Sketch a flower, and name the differ- 

 ent parts of the corolla ; what name is given to such a flower ? 



The stamens (remove the corolla) ; how many stamens are there ? What 

 is their relation to each other ? What terms are used to indicate such a re- 

 lation of stamens to each other ? 



The pistil. — How many carpels in the pistil ? Is it simple or compound ? 

 Sketch a young pistil, naming the parts. 



