No.423.] NORTHERN POLYPETALOUS. FLOWERS. 207 
white or greenish white; but in most species of Clematis the 
color is purple. By hybridization a great variety of hues have 
been produced, including blue, red, cream, and yellow. The 
calyx of Hepatica is white, rose, or blue. Kerner remarks that 
the flowers, which appear as soon as the snow leaves the ground 
in open woods, by their blue color present a strong contrast 
against the yellow-brown leafage, whereas in green meadows 
they would scarcely be seen. The occurrence of blue sepals is 
rare and is perhaps nowhere so well shown as in this family. 
From this brief survey of the coloring of the calyx it is evident 
that its capability for developing a wide range of colors equals 
that of the corolla. Though commonly green and only protec- 
tive, it may give rise to any color. 
In other genera of the Ranunculacez the petals are present 
but are transformed into nectaries. In Eranthis and Helleborus 
they take the form of a trumpet ; in Isopyrum they are spoon- 
shaped, in Nigella lamp-shaped ; ; in Coptis they resemble a hood, 
in Aquilegia a horn of plenty; and in Delphinium the two 
upper sepals and petals are both spurred. Tubular petals have 
also been observed in Ranunculus repens by Masters.! This 
tendency is inherent in the flowers and not induced by the 
agency of insects, and has greatly aided in the production of 
the different genera. The sepals of all these flowers are con- 
spicuous.. In Helleborus viridis the calyx is yellowish green, 
and in H. niger, ^or Christmas rose, which blooms in winter, the 
flowers are at first white, turning pinkish, and then green. 
Trollius laxus, which grows in the shade of dense swamps, 
has greenish-yellow flowers, while 7. europeus has bright yellow 
sepals. Coptis trifolia, a woodland plant, has small white flowers 
in springtime. 
The species formerly included in the genus Ranunculus, but 
now segregated into several genera, have the petals large and 
regular. The nectar is secreted in a little pit near the base. 
The thirty-one species of Ranunculus native in the northern 
states are yellow, or whitish in R. xivalis, or occasionally in 
R. acris in autumn. A wide range of colors is displayed by 
KR. asiaticus, including yellow, red, purple, and nearly black. 
1 Vegetable Teratology, p- 23. 
