214 ` THE AMERICAN NATURALIST. | [Vor. XXXVI. 
with a network of dark red veins. Of the five northern species 
of Drosera, four have white and one purple flowers. The red 
glandular leaves are far more prominent than the flowers. In 
the common D. rotundifolia the small white flowers open at 
midday, one or two at a time, and are visited sparingly by flies. 
The order Rosales includes some thirteen families, differing 
but little from each other. The Saxifragacez, according to 
Engler, form the center of development, while the Rosaceze and 
Papilionaceze are regarded as sister families. The primitive 
character of many of the genera appears in the indefinite num- 
ber of the stamens and pistils and their separate insertion upon 
the receptacle. The order, however, exhibits an advance upon 
the Ranales in that the carpels are more often united and the 
ovary inferior. 
Of the Crassulacez, or orpine family, two species are green, 
two white, five yellow, two red, and two purple. The two green- 
flowered species have small flowers and grow in wet places, and 
in the case of Penthorum sedoides (ditch stonecrop) the petals 
usually are wanting. The genus Sedum (stonecrop) contains 
white, yellow, red, and purple flowers, with the honey readily 
accessible to short-lipped insects. In S. acre the leaves are 
yellowish green and the flowers yellow. While the blossoms 
are small they are produced in such profusion that they completely 
cover the plants, which grow in dense tufts and are sometimes 
called “golden moss.” In S. telephium the petals are purple 
and often the entire plant. The honey is more deeply concealed 
than in the preceding species, and the flowers are in broad cymes, 
which are conspicuous and facilitate insect visits. In the species 
of Sempervivum the honey is still more deeply hidden and can 
be reached only by long-tongued insects. The cymose flowers 
are showy pink or purple. The petals of Sempervivum wulfentt 
are sulphur yellow with a purple base, and are pollinated by 
bumblebees. This purple coloring Miiller believed to be a rem- 
nant inherited from a purple-flowered ancestor, from which the 
sulphur-yellow form, which is unlike the primitive yellow form 
of Sedum, had been developed by the selective influence of 
bumblebees. This color change is not improbable, for the petals 
of Arnebia cornuta, when they expand, — with dark 
