Page:The Journal of Indian Botany.djvu/13

 DIMORPHIC CARPELLATE FLOWER OF ACALYPHA INDICA, L.

BY

Agricultural Institute, Allahabad.

Acalypha indica L. is a common member of the Euphorbiacese growing over most of India as a weed on waste ground. It is said by Hooker to grow over a wide tropical area, from the Philippines to Tropical Africa.

The flowers are apparently in spikes ; but a closer examination shows that the flower cluster is in reality a racemose cyme, each of the branches from the main axis being a cyme of three or more flowers. The lower branches, which are almost concealed by large bracts, bear trilocular carpellate flowers closely resembling in structure the carpellate flowers of Bicinus and the Euphorbiacese in general. Higher on the axis and with much smaller bracts are cymes of staminate flowers, while at the very tip without a bract is a peculiar bilaterally symmetrical unilocular carpellate flower which bears a single seed. This flower has three or four sepals which vary considerably in their position, and a monocarpellary pistil. The ovary is a transverse cylinder slightly depressed at either end and resembling a muff in appearance. The attachment of the stalk and sepals is to the curved surface midway between the ciliate-bordered ends. Arising from this point of attachment is the style. It resembles the style of a single carpel of the trilocular pistil except for its basal position and the fact that it is more fimbriate, having six to eight thread-like branches instead of three to five.

As the flower develops into the fruit the upper part of the cylin- der elongates so that in its front or rear aspect the fruit is triangular with its apex downward. The edges are extended as hollow auricles which are fringed and rugose. The whole appears like a rhombic leaf bent so that the tip touches the base and enclosing a seed at its center.

To determine the significance of this terminal flower, inflorescence tips of various ages were killed in chrom-acetic acid, imbedded in paraffin, and sectioned. It was found that this flower starts as a