Convolvulus, FieldBotanical Name: Convolvulus arvensis (LINN.)
Family: N.O. Convolvulaceae
Synonyms: Cornbind. Ropebind. Withywind. Bearwind. Jack-run'-in'-the-Country. Devil's Garters. Hedge Bells.
Parts Used: Root, root resin.
Although the blossoms of the Field Convolvulus (C. arvensis) are some of the prettiest and daintiest of our native wild-flowers, the plant which bears them ranks among the most troublesome of weeds to the farmer not only creeping up his hedges, but strangling his corn and spreading over everything within its reach. In North America it has intruded as a most unwelcome immigrant, persistently covering the ground with its trailing stems.
Its roots run very deeply into the ground and extend over a large area. It is, therefore, extremely difficult to extirpate, for the long roots are brittle and readily snap, and any portion left in the ground will soon grow as vigorously as ever and send up shoots to the surface, so that in a very brief time it is again spreading over the ground and climbing over everything in its way.
Its delicate creeping stems grow with great rapidity, either when found on banks trailing along the ground amidst the grass or climbing wherever they find a support. Their ends swing slowly and continuously in circles and twine round anything with which they may happen to come in contact. It has been found that a Bindweed stem in favourable circumstances will make a complete revolution in about 1 3/4 hours, which explains the rapidity of its growth.
The generic name of the plant is derived from the Latin convolvo (to intertwine), and is descriptive of its general growth, for it does not, like many climbers, support itself by tendrils, but the whole plant twists itself tightly round the object that supports it - ordinarily a stalk of corn, or some other plant or object of similar size: it is never found twining round anything of bulky dimensions, such as gate-posts, etc. Its English name, Bindweed, is similarly given it for its habit of twining round and matting together all other plants near it. The Latin specific name, arvensis, is derived from arvum (a cornfield), because this species of Convolvulus, though commonly enough met with in waste places, is one of the characteristic flowers of the cornfield.
Professor Henslow remarks that this Field Convolvulus invariably twines round some stalk or object of small diameter.
Description: It is a perennial and has a long period of blooming, generally beginning to flower about the first week of June, and being found in blossom throughout the summer and autumn months. The leaves are arrowshaped in form, but often very variable, the extremity of the leaf being in some cases far more acute than in others, and the lobes at the base more elongated. They are placed singly along the stem at very regular intervals.
From the axils of the leaves - the points at which their stalks join the main stemspring the flower-stalks, one to each leaf all up the stem. These flower-stalks often fork into two smaller ones, each bearing a bud. One of these lesser stalks is almost invariably smaller than the other, bearing a bud in an earlier stage of development, so that although the buds occur in pairs on the flower-stem, the flowers never expand at the same time, but always appear singly. At the junction of the flower-stalk and the main stem are a pair of very small scale-like bracts.
The flowers have trumpet-shaped corollas which vary a great deal in colour - in some plants they are almost white, whilst in others the normal pink becomes almost crimson. On the underside are five dark pink rays. In the bud the petals are folded into five pleats, the outermost part of the fold being these deep pink rays. At the bottom of the flower are what appear to be the mouths of five tubes, or pipes, running downwards, the tubes being formed by the flattened filaments of the stamens being joined to the corolla tube and yet projecting ridge-like into the flower. Flowers with tubes like these are known as 'revolver flowers,' because of the resemblance to the barrels of a revolver: the Gentians are another example. These tubes lead to the nectar which is contained in five small sacs, one at the base of each tube. To get to the honey an insect has to thrust its proboscis down each tube in turn, but whilst doing so, he knocks against the pollen in the anther placed just above it, and by carrying that pollen to the next flower it effects its cross-fertilization. In spite of this arrangement, it is a strange and unexplained fact that the flowers seldom set seeds, though the open corollas are visited by many insects, attracted by the nectar and by the faint perfume of vanilla that characterizes it. The failure to set seed is, however, quite compensated for by the vitality of its widely spreading, much branched roots, on which it chiefly depends for its propagation.
The Convolvulus is very sensitive to weather conditions, always closing in rain, to open again with the return of sunshine. It also closes at night. Its blossoms give a deep yellow or orange tint to water, which is heightened by alum and alkalies.
It is found wild throughout Europe, in Siberia, China, Persia and India, in North America where it has been introduced, and in Chile.