one is fragrant and has a lip of a deeper shade of yellow. ” 
Rydberg (Torreya 2 (1902) 86), writing in defence of 
his key to the yellow Cypripedium in Britton’s Manual 
of the Flora of the Northern States and Canada (1901) 
p. 290), arrived at the following conclusions: 
“1. That C. hirsutum Mill, has been rightly under¬ 
stood by me, and wrongly so by the English botanists 
and by Gray. 
“2. That either do we have three species of yellow 
lady’s slipper, one large and one small-flowered, both 
with vertically flattened lip, and a third medium-sized 
one with laterally flattened lip; or else was C.parvfflo- 
rum Salisb. a small flowered form of C.hirsutum. 
“3. In either case, the one with laterally flattened lip 
is neither C.pubescens nor C.parviflorum. 
“4. If there are three species their names. . . would 
be as follows: 
1. C. hirsutum Mill. . . . 
2. C. fiavescens [de Candolle]. . . 
3. C.parviflorum Salisb. . . . ”. 
Miss Niles (Bog-trotting for Orchids (1904) 57) ar¬ 
rived at practically the same conclusions as those of Ryd¬ 
berg. She said: ‘ ‘There seem to be three different forms 
of the Yellow Cypripediums, although there are but two 
distinct North American species north of Mexico; these 
appear also to intergrade frequently. Close association 
of habitat has probably something to do with this cross¬ 
fertilization of the two species. ” She also said: “Finding 
the two marsh plants, Cypripedium hirsutum and Cypri¬ 
pedium parviflorum, growing side by side in the Swamp 
of Oracles [Vermont], I observed marked intergrading, 
. . . the large species, Cypripedium hirsutum , producing 
variegated sepals and petals, or possibly now and then a 
brown-pink petal or sepal, imitating the type species of 
[5] 
