The leaves seem to be paired, but are really deeply lobed, their outer edges rounded, the notch cut in deeply. The nerves are almost parallel. This peculiar leaf shows the relationship of this vine to other members of the same family, especially the Orchid tree and the St. Thomas tree. The genus was named for the twin Bauhin brothers who were herbalists in the 16th century.
The flowers are followed by long, flat, purplish-brown pods, showing this plant belongs to the legume family. Its native home is China. (Plate XII)
SANDPAPER VINE. PURPLE WREATH _Petrea volubilis Linnaeus_
One of the most exciting experiences in Hawaii is to come upon a plant of the Petrea in full bloom. The cascading racemes of lavender-blue flowers cover the plant completely, turning it into a tumbling fall of lacy blue. The calyx seems like a flower in itself, being starlike, five pointed and periwinkle blue. The true flower is a rich violet in color and looks something like a real violet growing in the center of the calyx. This true blossom falls off the plant in a day or so, leaving the calyxes to suggest a cluster of Wistaria blossoms. Each raceme is seven or eight inches long and carries fifteen to thirty flowers. The plant blooms several times during the year, at least once in spring and again in summer.
The leaves are yellowish or grey-green and very rough in feeling. They give the plant its name of Sandpaper vine. It is a native of Brazil and a member of the Verbena family. A specimen may be seen on Metcalf street, near Hunnewell. (Plate XII)
ORCHID VINE _Stigmaphyllon littorale A. Jussieu_
Clusters of delicate, yellow flowers, suggesting small yellow orchids have given the name of Orchid to the two Stigmaphyllons which grow in Hawaii. They are, however, in no way related to Orchids but belong to the Malpighia family. In recent years they have become very popular in Honolulu but cannot yet be found widespread in gardens.
Individual blossoms have five unequal petals of a crepy, satiny, texture and a clear bright yellow color. The flower illustrated in Plate XII is _Stigmaphyllon littorale_. Its flowers are smaller and more numerous than the cousin, which is _Stigmaphyllon ciliatum_, but the form of the two flowers is very much alike. The foliage of the two plants, however, is different for while both have strong, leathery, shining leaves, those of _S. littorale_ are oval, while those of _S. ciliatum_ are small, pointed, quaintly heart-shaped and as the botanist says, they are “ciliate,” that is, fringed by coarse hairs. From this is derived its specific name of ciliatum.