(Calystegia sepium of Gray)
FlowersLight pink, with white stripes or all white, bellshaped, about 2 in. long, twisted in the bud, solitary, on long peduncles from leaf axils. Calyx of 5 sepals, concealed by 2 large bracts at base. Corolla 5-lobed, the 5 included stamens inserted on its tube ; style with 2 oblong stigmas. Stem: Smooth or hairy, 3 to 10 ft. long, twining or trailing over ground. Leaves: Triangular or arrow-shaped, 2 to 5 in. long, on slender petioles.
Preferred HabitatWayside hedges, thickets, fields, walls. Flowering SeasonJuneSeptember.
DistributionNova Scotia to North Carolina, westward to Nebraska. Europe and Asia.
No one need be told that the pretty, bellshaped pink and white flower on the vigorous vine clambering over stone walls and winding about the shrubbery of wayside thickets in a suffocating embrace is akin to the morning-glory of the garden trellis (C. major). An exceedingly rapid climber, the twining stem often describes a complete circle in two hours, turning against the sun, or just contrary to the hands of a watch. Late in the season, when an abundance of seed has been set, the flower can well afford to keep open longer hours, also in rainy weather ; but early in the summer, at least, it must attend to business only while the sun shines and its benefactors are flying. Usually it closes at sundown. On moonlight nights, however, the hospitable blossom keeps open for the benefit of certain moths. In Europe the plant’s range is supposed to be limited to that of a crepuscular moth (Sphinx convolvuli), and where that benefactor is rare, as in England, the bindweed sets few seeds ; where it does not occur, as in Scotland, this convolvulus is seldom found wild ; whereas in Italy Delpino tells of catching numbers of the moths in hedges overgrown with the common plant, by standing with thumb and forefinger over a flower, ready to close it when the insect has entered. We know that every floral clock is regulated by the hours of flight of its insect friends. When they have retired, the flowers close to protect nectar and pollen from useless pilferers. In this country various species of bees chiefly fertilize the bind-weed blossoms. Guided by the white streaks, or pathfinders, they crawl into the deep tube and sip through one of the five narrow passages leading to the nectary. A transverse section of the flower cut to show these five passages standing in a circle around the central ovary looks like the end of a five-barrelled revolver. Insects without a suitably long proboscis are, of course, excluded by this arrangement.
From July until hard frost look for that exquisite little beetle, Cassida aurichalcea, like a drop of molten gold, clinging beneath the bindweed’s leaves. The small perforations reveal his hiding places. ” But you must be quick if you would capture him,” says William Hamilton Gibson, “for he is off in a spangling streak of glitter. Nor is this golden sheen all the resource of the little insect ; for in the space of a few seconds, as you hold him in your hand, he has become a milky, iridescent opal, and now mother-of-pearl, and finally crawls before you in a coat of dull orange.” A dead beetle loses all this wonderful lustre. Even on the morning-glory in our gardens we may sometimes find these jewelled mites, or their fork-tailed, black larvae, or the tiny chrysalids suspended by their tails, although it is the wild bindweed that is ever their favorite abiding place.
The small Field Bindweed (C. arvensis), a common immigrant from Europe, which has taken up its abode from Nova Scotia and Ontario southward to New Jersey, and westward to Kansas, trails over the ground with a deathless persistency which fills farmers with dismay. It is like a small edition of the hedge bindweed, only its calyx lacks the leaf-like bracts at its base, its slender stem rarely exceeds two feet in length, and the little pink and white flowers often grow in pairs. Their habit of closing both in the evening and in rainy weather indicates that they are adapted for diurnal insects only ; but if the bell hang down, or if the corolla drop off, the pollen must fall on the stigma and effect self-fertilization. Many more insects visit this flower than the large bindweed, attracted by the peculiar fragrance, and led by the white streaks to the orange-colored under surface of the ovary, where the nectar lies concealed. Stigmas and anthers mature at the same time; but as the former are slightly the longer, they receive pollen brought from another flower before the visitor gets freshly dusted.