218 THE AMERICAN NATURALIST. [VoL. XXXVI. 
and the male greenish yellow and much more conspicuous, 
though of no larger size. By this device insects are induced to 
visit the male, or pollen-bearing flowers, first. The petals of 
R. sanguineum change from white to pink, and of R. aureum from 
yellow to carmine. This color change, says Müller, also occurs 
in several species of Fuchsia and Lantana and enables the more 
intelligent bees to economize time by determining instantly those 
flowers which no longer contain nectar. 
There are four green, thirty-five white, thirty-nine yellow, 
thirteen red, and four purple flowers in the Rosacee. The green 
flowers are small and apetalous, as in Alchemilla; the white 
flowers are very generally tinged or tipped with red, and 
vary from small in Spirzea to large in Rubus. Of the twenty. 
genera in the northern states, twelve contain white flowers. Of 
the four species in Spirza, three are white and one, .S. tomentosa 
(hardhack), is rose, or rarely white. The flowers contain nectar 
and attract numerous flies, beetles, and Hymenoptera. Beetles 
are very frequent visitors to the small white flowers of Aruncus 
aruncus. The genus Rubus contains seventeen species, all of 
which are white except the purple R. odoratus and the pink 
R. arcticus. R. strigosus, or the wild red raspberry, has small, 
erect white petals, and the visitors are much fewer than to the 
blackberry, R. villosus. Though the flowers of the blackberry 
are also white, their increased conspicuousness secures them a 
much larger company of visitors, which is not far from one 
hundred. The petals are broad and flat, and the panicles large 
and numerous. Dalibarda repens, a woodland plant, produces 
both cleistogamic and open white flowers which are seldom 
fertile. The common field strawberry blooms in May and June, 
when the white blossoms contrast with the green meadow, and 
the growing grasses are as yet too short to conceal them. 
Of the twenty-four species of Potentilla, two, P. arguta and 
P. tridentata, are white and are probably derived from yellow- 
flowered ancestors. They both grow in dry, rocky places, The 
other twenty-two species are yellow and are visited by small 
bees and flies. The prevalence of yellow coloring in this primi- 
tive genus would indicate its early development in the rose 
family. — M —— À —ÀÁ 
