224 THE: AMERICAN NATURALIST. [VoL. XXXVI. 
beetles, or bees. Cultivated species of Oxalis are red or rose. 
O. flava is yellow, edged with: red; and ©. versicolor is white 
above and red beneath, so that the blossoms are white in the 
sunshine, and red when rolled up in the shade. 
Like the Papilionacez, the flowers of the Polygalacez stand 
horizontal, and the petals are more or less united into a tube 
with a carina and ale. The largest-flowered species is the 
fringed Polygala, P. paucifolia; which in spring produces beau- 
tiful rose-purple crested blossoms, "with an occasional white 
variety. It is attractive to butterflies as well as bees. On the 
Alps, Müller found one species of Polygala fertilized entirely by 
butterflies. Most of our species have very small flowers, which are 
either greenish purple, or yellow changing to green in drying. 
In the capability of the leaves to develop bright colors, and 
in the minute and reduced flowers attractive to Diptera, the 
Euphorbiacee, or spurge family, resemble the Aracez, though 
it has not the remarkable adaptations for fertilization of. Arum. 
The spurge family is of immense size and of very wide geograph- 
ical distribution. The flowers are minute and have undergone 
much reduction. They are usually apetalous, and the entire 
perianth may be wanting, as in Euphorbia, where a single stamen 
represents a flower, and the flower cluster with its colored invo- 
lucre was mistaken by the older botanists for a single flower. 
The genus Euphorbia is attractive to flies, though also visited 
by beetles and Hymenoptera; and in response to their visits the 
inflorescence in certain species possesses bright colors, honey, 
and a honey-like scent. The colors of many northern species are 
green, but a part are white, yellow, rose, or red. On £. . cypa- 
rissas, the common cypress spurge, naturalized from Europe, 
and which has escaped from cultivation, the bracts are yellow. 
In the Alps, Müller collected twenty-one flies, one beetle, four 
Hymenoptera, and three Lepidoptera on the flowers, and in 
middle Germany he found many more Coleoptera and Hymenop- 
tera. The genera Ricinus and Croton are extensively cultivated 
for the tropical aspect of the magnificent mode Rino com- 
munis is anémophilous. 
In the order Geraniales, to which the families, just considered 
belong, and in the succeeding. order, the Sanders, the flowers 
