TYPE STUDIES, SEED PLANTS 185 



166. Family ViolaceEB. Study any species of violet ; if some of tlie points 

 suggested in the following outline do not fit the species in hand, omit them. 

 Viola palmata. 



A. Sketch the entire plant. 



B. Has it any stem ? Explain. 



C. Sketch one of the first leaves of the season and a later one. 



D. Sketch a flower in profile in its natural position. 



1. What kind of symmetry has it? Does the flower, seen from in 

 front, appear open or closed ? How much of the stamens and pistils 

 can be seen ? 



2. Make a diagram of the cross section of the flower. 



3. Remove the petals. Is the spur a part of the calyx or the corolla ? 

 It serves as a nectary. 



4. Note the two nectar glands which project from stamens into 

 the spur. 



5. Make a sketch of the magnified pistil, surrounded by the stamens. 



6. Are the filaments united ? the anthers ? Do the anthers discharge 

 inwardly or outwardly ? Is the pollen dry or sticky ? 



7. Note that the pollen when shed collects in a sort of cone formed by 

 the united anthers, which is closed at the narrow end by the pistil. 

 When a visiting insect, as a bee seeking nectar, thrusts its tongue 

 into the small end of the cone, what would become of any pollen 

 which the insect brought with it ? Would other pollen be carried 

 away ? Result ? 



8. Thrust a slender, moistened toothpick gently into the opening of the 

 corolla, and after withdrawing examine it with a lens. Result ? 



9. What means have violets of advertising their supply of nectar ? 

 Compare the attractiveness of several species. 



10. Look for insect visitors. Do they all explore the interior of the 

 flower, as shown in Principles, Fig. 325 ? 



11. Many violets form most of their seed from apetalous cleistogamous 

 flowers (see Principles, Sec. 408). Is Viola palmata one of these ? 

 Study specimens in late summer or early fall to determine this point. 

 What are some advantages of cleistogamy ? disadvantages ? How 

 would a plant with some insect-pollinated flowers and other cleistog- 

 amous ones avoid the disadvantages mentioned ? 



E. What mechanism have the capsules for distributing seeds ? 



F. Are any violets moderate xerophytes ? Are any hydrophytes ? Does 

 the species studied belong to either class ? 



The Violace(B constitute a small and unimportant family, but the flowers 

 are decidedly interesting from the perfection of their adaptation for cross 

 and self pollination. 



