Illustrations of Indian Botany, Vol. 1/Elatineae

by Robert Wight

XX.—ELATINEAE.

A small and unimportant order of herbaceous, marsh, plants, found in all the four quarters of the globe. The stems are ramous, the leaves opposite, stipulate, the flowers small, usually aggregated in the axis, hermaphrodite.

Calyx of from 3 to 5 sepals. Petals as many alternate with them. Stamens either equalling the petals or twice as many. Ovarium 3, 4, or 5-celled with as many styles and stigmas, placentae in the axis bearing numerous ovules. Stigmas capitate. Fruit, a capsule, three 5-celled, three 5-valved, dehiscence either septicidal or loculicidal. Seeds numerous. Albumen sparing or wanting. Embryo cylindrical, radicle next the hilum.

Affinities.

These do not appear to me by any means clear. Formerly they were referred to Caryophylleae, thence Cambessides removed them as a distinct order, on account of their ex-albuminous seed, and capitate stigmas, to which loculicidal dehiscence is added. Both however being alike in that respect, that last character, which by the way is not constant, since I find in. at least two species of Bergia the dehiscence septicidal and not loculicidal, can be of little or no value ; unless perhaps as one by which we may keep Bergia distinct as a genus, from Elatine. The exalbuminous seed and capitate stigmas, while they afford very sufficient grounds for separating them from Caryophyllaceae which have a copious mealy albumen with the embryo rolled round it, and linear stigmas, associate the Elatineae with Lythrariae, in which order, Bartling (Ordines Plantarum) has placed them. From these however, it appears to me, their distinctly hypogynous stamens, numerous stigmas, and free ovaries sufficiently remove them. Dr. Lindley places them in an alliance distinguished by having "albumen present in the seeds" along with Lineae, an arrangement, the propriety of which I confess myself unable to perceive, as the albumen in Elatineae is almost if not entirely wanting.

Essential Character.

Polypetalous: stamens fewer than 20: ovary wholly superior; placentas in the axis; styles distinct to the base; calyx imbricated ecalyculate: leaves opposite, furnished with stipules.

Geographical Distribution.

The plants of this small order are found in moist, marshy grounds in all the four quarters of the globe—Elatine and Bergia are found in India. B. verticillata is common about the banks of water courses and rice fields, while B. ammannoides is more commonly seen in moist sandy soil near the banks of rivers, and in rice fields near the sea coast. Elatine ambigua I have only found in the moist soil of half dried tanks in the Tanjore district, where it forms large green patches.

Properties and Uses.

The properties of this order are unknown, if the species possess any. In England Elatine has received the rather questionable name of "water pepper" which seems to indicate the possession of acrid properties, though that seems doubtful as it is no where men-

tioned, and in this country the Bergia amrnannoides has, in Tamul, received that of Neer-mel-neripoo, or water-fire, a curious coincidence of names in countries so remote.

Remarks on the Genera.

Dr. Arnott and myself following Delile, referred the genus Bergia to Elatine whether judiciously or not may be doubted, now that I find the dehiscence of Bergia is septicidal while that of Elatine, as appears from the statements of those who have examined it with care, is loculicidal. This distinction combined with the difference of habit, of the two sets of plants, might I think with propriety be employed as a distinction to keep them generically separate, notwithstanding the similarity of their flowers, on which account, I, in this work, retain the old name of Bergia for the Elatine verticellata and E. ammanioides of our Prodromus, to which work however, I refer for the distinguishing characters. The accompanying plate represents a species of each genus.

EXPLANATION OF PLATE 25.

A. 1. Plant of Bergia ammannoides. Natural size. 2. Portion of a branch slightly magnified to show the stipules and aggregated axillary flowers. 3. Flowers opened, showing the sepals, petals, stamens, ovary, and stigmas. 4. Stamens separate, back and front views. 5. Mature fruit. 6. The same after dehiscence, the persistent calyx removed. 7- Capsule cut transversely. 8. A seed. 9. The same cut transversely. All more or less magnified.

These figures show the strong tendency that exists in this species, to variation in the number of the parts of the verticels of the flower, 3, 4 and 5 pieces occurring indiscriminately in different flowers, picked from the same stalk.

B. 1. Elatine ambigua. Natural size. 2. A plant removed from the soil and slightly magnified, showing its repent habit. 3. Portion of a branch more magnified. 4. Flower opened. 5. Capsule. 6. The same after dehiscence. 7. A seed. All more or lees magnified.

ELATINEÆ

A. BERGIA AMMANNOIDES. B. ELATINE AMBIGUA.