No. 390. ] MONOCOTYLEDONOUS FLOWERS. 501 
alone on the wing ; during two years I have repeatedly exam- 
ined many blossoms of the handsome Pogonia ophioglossoides, 
but have collected only a single specimen of Bombus consimilis. 
The white flowers of Gyrostachys (Spiranthes) and Peramium 
(Goodyera) are also occasionally visited by bumblebees.. The 
genus Habenaria is adapted to Lepidoptera, the white and yel- 
' lowish species, which are often sweet-scented, being pollinated 
by crepuscular or nocturnal moths. In some instances I have 
found the grayish hairs of these insects adhering to glutinous 
surfaces. The fertilization of some 10 species has been 
described by Asa Gray. Small purplish or green flowers are 
visited by small Hymenoptera and Diptera or are self-fertilized. 
On the purplish and greenish inflorescence of Listera, tway- 
blade, Darwin collected in England small Hymenoptera and Dip- 
tera, and on the extremely small and inconspicuous but odorous 
flowers of Herminium mornorchis George Darwin collected 27 
specimens of minute Hymenoptera, Diptera, and Coleoptera, the 
largest being less than +; of an inch in length. The small green 
flowers of Habenaria hyperborea and Epipactis viridiflora are 
self-fertilized. Scentless plain green flowers of a species of 
Epidendrum in South Brazil, according to Fritz Müller, freely 
secrete honey and attract insects. 
A simpler and earlier stage of the Orchidacez has been 
partly preserved in Cypripedium, the floral organs of which are 
less modified than those of other genera. An enormous amount 
of extinction, Darwin believes, has swept away the intermediate 
forms. The flowers are visited with extreme rarity by Andreni- 
dæ, while species of Bombus are liable to be held captive and 
perish miserably of starvation. Of the 6 species in the north- 
ern states, 2 are yellow, marked with purple, 2 white striped 
with purple, and 2 red and white. As the lip is evidently the 
chief object of attraction the other perianth®segments are dull 
colored, green, brown, white, or purple. 
The Orchidacez are remarkable for the variety of colors, 
often three or four, presented by individual flowers; in a spe- 
cies of Dendrobium from India the sepals and petals are white, 
tipped with purple, and the lip is bright orange with two crim- 
son spots. This is probably due to the marked tendency of 
