SCROPHULARIACEM. 277 



Compare if possible other members of the mint family in the study of cross- 

 pollination. 



Material. — Entire plant with flowers and ripe fruit. If fresh plants are 

 not at hand, those that have been pressed and dried may be used for the 

 study of the entire plant and of the leaves. The flowers may be preserved in 

 formalin. 



Order Personatve. 



Exercise 80. 



439. The figwort family (scrophulariaceae). — Toad flax (Linaria vul- 

 garis). — The toad flax is widely distributed, growing in waste places as a 

 weed from June to October. 



The entire plant. — Note the short, pale green perennial root stock ; the 

 longer erect annual stem ; is it simple or branched ? Leaves, form and ar- 

 rangement. 



The inflorescence. — The kind of inflorescence. The flower. — What parts 

 of the flower are present ? Describe the different parts. The calyx. — How 

 many sepals indicated ? what is the form of the calyx ? The corolla. — Form. 

 How many petals indicated ? Describe the form of the corolla and its parts. 

 The stamens. — How many, their position, size? What is the significance of 

 the difference in the size of the stamens? The pistil. — Form, parts ; form of 

 the ovary ; how many carpels present in the pistil ? 



Study the adaptation of the flower for cross-pollination by the aid of insects ; 

 the lower lip of the corolla as a landing place ; since insects are supposed to 

 be attracted by bright colors, what portion of the flower serves thus to direct 

 the insect ? 



Note the spur on the corolla, and the nectar inside ; what kinds of insects 

 visit this flower ? Imitate with the end of a pencil the entrance of an insect 

 in a flower and endeavor to make out how cross-pollination takes place. 



Seed distribution. — Examine ripe seed pods, dry some of them, and then 

 take some of the dry ones and place in water. Describe the action of the 

 pod in scattering the seeds, and the causes. 



Other members of the family are interesting to compare with the toad flax, 

 as the beard tongue (Penstemon pubescens), turtle head (Chelone glabra), 

 monkey flower (Mimulus ringens), etc. 



Material Entire plants with the underground stems. Flowers and 



fruit. If fresh material cannot be had at the time of the study, dried plants 

 (pressed) will answer for the study of the entire plant. Flowers may be pre- 

 served in formalin ; fruits dry. 



