Page:Illustrations of Indian Botany, Vol. 2.djvu/358

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ILLUSTRATIONS OF INDIAN BOTANY. Calyx tubular, persistent, 5-lobed, at first slightly, afterwards more distinctly two-lipped (owing to the enlarging ovary splitting it on each side). Corolla hypogynous, monopetalous, salver-shaped ; tube cylindrical ; limb spreading, 5-7-lobed (lobes obovate, cuniate, sub-emarginate). Stamens 2, inserted within the tube, incluse; filaments short ; anthers oblong, 2-celled; cells parallel, contiguous, dehiscing longitudinally. Ovary free, 2-celled; ovules 4 in each cell, pendulous from near the apex of the septum. Style about the length of the tube ; stigma bifid. Capsule obovate, cuniate, very obtuse above, hard, rough, woody, 2-cell- ed, dehiscing loculicidally (through the middle of the partition as in Acanthaceoe), valves septiferous. Seed 4 in each cell, pendulous from the apex, oblong, ending below in a long sub-lanceolate wing; testa smooth, endoplura somewhat thick, spongy, embryo exalbuminous, radicle short, next the hilum, cotyledons oblong, fleshy, longitudinally plaited. — A tree with opposite, exstipulate, pinnate leaves, trichotomous panicles, minute bracts. "Flowers small, variegated, white and brown, fragrant, especially during the night." Roxb.

Roxburgh's specimens were from the Circars. Those from which the accompanying draw- ings were made, I gathered in Mysore, and I can recall having once seen the tree on the eastern slopes of the Neilgherries, below Kotergherry, but not in flower. I never, so far as I can now recollect, met with it growing in the Circars in the jungles of which it would, from Roxburgh's account, appear to abound. It is rare in Southern India.

My analysis of the ovary (Plate 1 62) is less perfect than I could have wished, owing to nearly all the flowers on my solitary specimen being injured by insects; I had, therefore, to use young fruit, of the size represented, fig. 7, from which the figures 8, 9, 10 and 11 were taken.

Further explanation of that plate seemes scarcely necessary, beyond merely remarking that No. 15 is the cotyledons denuded of their covering, and 16", a cross section of a full-grown seed, showing the thickness of the endoplura and plaited cotyledons.

This small order of herbaceous plants was first indicated in 1810 by Mr. Brown in his Prodromus. It has since been enlarged by the addition of the section Sesamece, which, so far as I understand his observation under the ordinal character, he did not intend to include, but which seems better placed here than in Bignoniacece, in which Endlicher has stationed it. De Candolle adopted the order under the name of Sesamece including the original Pedalinece as a tribe in place of the primary order, a proceeding which has not been adopted by other authors. It is a curious order and, unless examined at a very early stage, before the corolla exceeds the length of the calyx, can scarcely be correctly understood. At that early stage the ovary is one-celled, with 2 or 4 rows of ovules, but as it advances it becomes, by the growth of partitions, divided into 2 or 4 cells. Two genera only are natives of India," Sesamum and Pedalium, the ovary of the former, at the period of impregnation, having 4, the latter 2 cells. The ovary in both genera is composed of 2 carpels, placed anterior and posterior to the axis. At the above mentioned early stage, the carpels of the former are each furnished within on the back with a thickened line, the dorsal nerve, which, as the ovary enlarges, extends to the centre forming a spurious partition, as in Bignoniacecc, having like them a row of seed lying on each side. By this secondary process the ovary becomes 4-celled all except the point. The difficulty of understanding the true structure is afterwards increased by the firm union of the two carpels, and the loculicidal dehiscence of the mature capsule through the middle of the spurious partition, presenting the appearance of right and left carpels and septicidal dehiscence. The placentae of the 4 edges of the 2 carpels usually meet and adhere in the centre, forming a 4-sided column easily separable (like the placenta of Bignoniaceas), with a row of seed on each angle. That this 4-sided placenta is thus formed, I have ascertained from occasionally finding it split along the middle (the placenta of each carpel not having adhered to the opposite one), thus showing its compound structure. The structure of Pedalium is similar in kind but wanting the thickening in the middle of the carpels, remains 2-celled, and the 4-sided capsule, becoming hard and woody, is indehiscent, and the angles furnished with 4 strong spines; presenting, when cut across, a most inexplicable appearance, one being altogether at a loss how to account for the production of