62 STUDIES IN THE VEGETATION OF THE STATE 



pistils elongating as they become older. Very few ovaries be- 

 come fertilized. 



The large bright blue blossoms of Viola pedatifida appear 

 about a week later than those of V. oUiqua, and, when min- 

 gled with the yellow of Lithospermum and of Garex meadii, 

 give a typica 1 vernal effect. Viola ped^atifida is one of 

 th(; most evenly distributed of our prairie species. It is found 

 on all of the slopes, crests of ridges, and to some extent in 

 the meadow formations. The greatest number found in any 

 quadrat is forty- two, and the average for seventeen quadrats, 

 for all except northern exposures, is twenty individuals. On 

 northern slopes two to twelve plants were growing in each 

 quadrat examined. Viola pedatifida, V. obliqua,, and others 

 of the genus have developed short, thick, fleshy rootstalks, by 

 virtue of which they are enabled to secure an early start in 

 the spring. I have not observed that rosettes of Viola pass the 

 winter months. Viola pedatifida is chasmo-cleistogamous, 

 but so far as observed few chasmogamous flowers are fertile. 

 The cleistogamous flowers are usually developed later and 

 are quite productive. The chasmogamous flowers are herko- 

 gamous, and inclined so as to receive no water upon the 

 pollen. The bright colored petals are folded and bearded, 

 apparently to protect the pollen. Dissemination is brought 

 about in the various violets by the closing together of the 

 walls of the valves of the ovary in drying. 



Oxalis violacea frequents low prairies and meadows, where 

 it forms circular, carpet-like patches of green and rose 2-i 

 meters in diameter. Oxalis has also established itself along 

 southern exposures of hedges, growing profusely in dense 

 carpets 15-25 meters in extent. The wood sorrel is perennial 

 by means of a scaly bulb, which explains its early appearance. 

 It is one of our prettiest vernal bloomers, appearing at a time 

 when the floral covering is sparse. Its flowers are hemeran- 

 thous and usually ephemeral, opening at 7 :30 a.m., and clos- 

 ing at 5 :30 p.m., remaining closed on cloudy days. The flower 

 pedicels are reflexed before and after anthesis. The filaments 



