446 MINNESOTA BOTANICAL STUDIES. 



horizontal orifice, and is bilobed because of an anterior fissure 

 forming another opening to the flower. In color it is a deep 

 rose and is irregularly roughened. The staminodium is acu- 

 tely rhomboidal with a prominent midrib. The two fertile 

 stamens are large, adnate to the column and bilocular. The 

 body of the deflexed column is slender with a thick, fleshy, 

 concave, triangular stigmatic area which has minute projec- 

 tions and is indistinctly three-parted. The ovary is inflated, 

 arcuate and coarsely ribbed, 



Cypripedium acaule Ait. is found in bloom in May and June, 

 in dry or wet ground under deciduous and evergreen trees from 

 Newfoundland to Port Franklin and through the entire Atlantic 

 region. It is prominent among the North American species as 

 being the only one nearly reaching the Arctic circle and extend- 

 ing well toward the Tropic of Cancer. In Minnesota it is fre- 

 quently found in tamarack swamps. 



According to Aiton^''"' Cypripedium acaule was introduced 

 into England in 1786, from North America, by Sir William 

 Hamilton. It was then known as the "Tw^o leaved Lady's 

 Slipper." It is also called the "Stemless Lady's Slipper," "^ 

 "Dwarf Umbil" ^^^ and "Noah's Ark" 'i^. In New Hampshire 

 it is called "Valerian" owing to an imaginary curative qual- 

 ity. It is also given the name of "Whip poor- will Shoe" i^^ and 

 in Connecticut, the flowers are called "Squirrel Shoes. "^-"^ 



Since C. acaule Ait. has an anterior entrance in addition to 

 the usual orifice, Gray^^i concluded that flies might have two 

 means of ingress as well as the two lateral ones, each side of 

 the column, for exit. When the insect does enter, it ultimately 

 brushes under the stigma and upon emerging, carries with it 

 some of the pollen from the stamens. This pollen Darwin 122 

 found to be immersed in a viscid fluid, which is capable of 

 being drawn out into filaments. 



The leaves of the species are large, indeed, they are the 

 largest of any of the Diphylla in America. The suggestion 

 has been made, that the leaves are large because the plant is 

 lowly and meets with less competition^-'* than do the taller plants. 



(115) Ait. Hort. Kew. 5:220. lSr2. 



(116) Gray, A. Man. Bot. 6 ed. 510. 1892. 



(117) Meehan. T. U. S. Fl. and Ferns 2. 8:61. PI. 15. 1880. 



(118) Torrey. .1. Fl. N. Y. 3: 286. 1813. 



(119) Bergpn, F. D. Bot. Gaz. 10:«0. 1891. 



(120) Bergen, F. D. Loc. cit. 



(121) Gray. A. How Plants Behave. 31. 1872. 



(122) Darwin. C. Fertilization of Orchids. 220. 1877. 



(123) Allen, G. Nature. Mch. 1883. 



