260 PLANT FAMILIES : DICOTYLEDONS. 



Order CistifloRj<e. 



420. The violet family (violacese). — The violet family is 

 represented by the common blue violet, the yellow violet, the 

 pansies, heart's ease, sweet violet, etc. 



Exercise 73. 



421. The blue violet (Viola cucullata). 



The entire plant. — Describe the character and habit of the plant, the short 

 underground stem, the ' ' radicle ' ' leaves, the erect flower scapes which bear 

 the conspicuous blue flowers, and the short, curved stems beneath the soil or 

 debris which bear the closed inconspicuous flowers. Sketch a leaf, showing 

 the form and venation. What is the form of the leaf and the character of 

 the margin ? 



The blue flowers. — Sketch a flower. Is the flower regular or irregular? 

 complete or incomplete ? perfect or imperfect ? 



The calyx. — Describe the form of the calyx ; how many sepals are indi- 

 cated ? 



The corolla. — How many petals are present ? Remove them and note care- 

 fully the form of each one and the position in the flower. In the " spurred" 

 one look for nectar glands. 



The stamens. — Determine the number of the stamens. Are they united 

 together by their anthers ? If so the stamens are said to be syngenecious. 

 Are the stamens of different sizes ? Describe the form of the different ones 

 and the relation of certain peculiar ones to the spur of the corolla. 



The pistil. — Describe the form of the pistil and the relation of the stamens 

 and pistils. 



The closed (cleistogamous) flowers. — These are on shorter, curved, scapes 

 which hold them beneath the soil or debris. Compare them with the blue 

 flowers. What parts of the flower are absent ? 



The fruit. — Make a cross-section of the fruit and determine how many car- 

 pels are represented in the pistil. Note the numerous seeds. 



Pollination of violets.— If a sweet violet flower, or the flowers of the pansy 

 are convenient, study the stamens and pistil of the open flowers. Remove the 

 corolla, and note the position of the anthers with reference to the pistil. 

 Note the peculiar enlarged stigma with an opening in front, and the lip below. 

 Move a pencil into a flower, endeavoring to imitate the entrance of an insec 

 and try to determine how cross-pollination takes place. Compare the blue 

 flowers of the blue violet. 



The small closed flowers are called cleistogamous, and they are self-polli. 



