Polygala rubella. Bitter Polygala.

Pl. 54. Polygala rubella. Also see Polygala rubella - Polygala senega.

This plant is interesting from the curious manner in which a part of the fruit is produced, by a kind of imperfect flower growing close to, and in some instances under, the surface of the ground. It is not the only species of the Polygala which has this peculiarity. I have often observed little shoots at the root of P. paucifolia, one of the most beautiful of the genus, bearing apterous flowers and subterranean fruit, precisely like those represented in our plate. The P. polygama, of Walter and Pursh, if, indeed, it is a distinct species, has the same remarkable mode of growth. It is difficult to imagine what end is attained by nature in this singular arrangement, by which a part of the seeds are ripened in the sun, while the rest, like the fruit of Arachis hypogaa, is buried from the light. To the eye there is no difference between seeds taken from the upper or lower racemes of the plant. It would be worth while to ascertain if the two will vegetate equally well.

The genus is marked by a calyx of five leaves, two of which are wing-like and coloured. Capsule obcordate, two celled and two valved. The species rubella has its stems simple; leaves linear-oblong, mucronated; flowers racemed, those of the stem winged, those of the root apterous.

Class Diadelphia, order Octandria; natural orders Lomentaceae, Linn. Pediculares, Juss.

The Polygala rubella, here described, is the plant designated by that name in Muhlenberg's catalogue, as I have formerly learnt from the author himself. There is little doubt that Willdenow's plant is the same, described from an imperfect specimen. It is found in dry, sandy, or gravelly soils in many parts of the United States, and flowers in June and July.

Root somewhat fusiform, perennial, branching. Stems numerous, ascending, smooth, angular, simple. Leaves scattered, smooth, the lower ones obovate, smaller; the upper ones linear-lanceolate, obtuse, mucronated, sessile. Flowers purple, short-crested, in terminal racemes. Bractes small, ovate-lanceolate, caducous. Wings of the calyx rhomboid-oval, obtuse, with a slight middle nerve. Corolla small, closed, of three segments, the middle one largest and crested by the division of its sides and extremity. Anthers eight, forming a double row, the filaments coalescing. Germ compressed, inversely heart-shaped; style deflexed; stigma bearded inside, with a prominence below it. Capsule inversely heart-shaped, nearly smooth, margined, and invested with the wings of the calyx. Seeds two, obovate, hairy, with a transparent appendage or strophiole on the inside. From the base of the stems proceed a number of prostrate shoots situated upon, and sometimes nearly under the ground, bearing a row of incomplete fertile flowers.

These flowers are furnished with a calyx without wings, a minute corolla and stamens, and a short style. The germ and fruit precisely resemble those of the more perfect flowers. Like some of the European species which it resembles in habit, this plant is a strong and permanent bitter, imparting its sensible properties both to spirit and to water. I digested a portion of the dried plant in ether, and added alcohol to the solution. No change was visible at the time of mixture, but on standing till the ether had partly evaporated, the alcohol became turbid. A tincture of the plant was not immediately affected by adding water, but on standing over night it became very turbid, and in a few days deposited a large precipitate. The bitterness, which is probably of the extractive kind, was communicated to cold, as well as hot water; and to alcohol. The aqueous solutions appear strong enough to represent the virtues of this vegetable.

The Polygala rubella, from its extreme bitterness, has attracted the notice of various medical practitioners in the Northern states. I have been assured by those who have tried its efficacy, that the infusion administered in small doses, proves a useful tonic and stimulant to the digestive organs. In large doses it opens the body and excites diaphoresis. Its powers appear to resemble those of Polygala vulgaris and P. amara of Europe, to which it has a close botanical resemblance; and which have enjoyed a certain degree of medicinal reputation as tonics and expectorants.

Botanical References.

Polygala rubella, Muhlenberg, Catal.
Willd. iii. 875.
Pursh, ii. 464.
Polygala polygama?
Nuttall, genera, ii. 87.

American Medical Botany, 1817-1821, was written by Jacob Bigelow, M. D.