188
ILLUSTRATIONS OF INDIAN BOTANY.
with small, roundish, crenato-dentate leaves, and rather large, brownish-purple flowers. Sesa- mum luteum, Retz, is still looked upon as an imperfectly known plant, as it does not appear to have been found since he described it.
Sesamum Indicum (DC).
- 1. A small flowering plant, natural size.
- 2. A very young flower-bud.
- 3. A flower more advanced.
- 4. One full blown.
- 5. Corolla split open.
- 6. Anthers, apiculate.
- 7. Corolla of fig. 2 detached and split open.
- 8. Ovary of fig. 2 cut transversely.
- 9. Ovary and calyx of an expanded flower.
- 10. Ovary detached and slightly magnified.
- 11. 12. Cut longitudinally and transversely, in 12 a
little stretched to show the origin of the spurious dissepiment.
OF PLATE 163.
- 13. Mature capsules.
- 14. Capsule in the state of dehiscence.
- 15. One valve of the capsule with the seed and spu-
rious partition in situ, showing the last free from the intermediate true partition.
- 16. Ripe capsule cut transversely.
- 17. A portion of the placenta? which separates after
shedding the seed.
- 18. A ripe seed.
- 19. The same cut across.
- 20. Detached embryo.
CXIII.— ACANTHACEAE.
This order was first indicated by Jussieu, but was at that time so little known that seven genera were found sufficient to include all the then known species. Brown subsequently added a few, as did Willdenow and others; but still, in 1830, when Bartling published his list, they scarcely amounted to 20. About that time Dr. Wallich placed the Indian division of the order in the hands of Professor Nees Von Esenbeck for description, when he, after an elaborate examination, raised the number for the Indian species alone to 56 ; and in 1840, when Endlicher's Genera Plantarum was completed, the number was raised to 80. In 1847 Nees published in DCs Prodromus a monograph of the whole order, which embraces 155 genera and about 1500 species. In this generally most masterly production he has on some occasions, perhaps, drawn the lines of demarcation between some of his genera too fine, rendering it probable that some of them may require to be reduced ; but on other occasions it seems equally probable that others may and will be divided. But be that as it may, this order furnishes a striking instance of the rapid advances now making in botany, and of the wonderful impulse which has, within the last 20 years, been given to this branch of science. To the Indian Botanist this is an interesting, but difficult, order, owing to the number of indigenous species, which are found in all parts of the country and in nearly all situations, inhabiting alike the marsh and most arid ground, the sea beach, and the tops of the highest mountains.
Character of the Order. Calyx pentamerous, the odd sepal posterior, sometimes the two anterior ones vinited, hence 4- or 5-divided, sometimes, but rarely, nearly obsolete, entire or several toothed. Corolla monopetalous, hypogynous, 5-cleft, the segments alternate with the sepals; limb usually bilabiate, but sometimes regular, 5-lobed, contorted in aestivation. Stamens inserted on the tube at different heights, sometimes near the base, about the middle, or on the throat, either didynamous, the 5th rudimentary or altogether wanting, or often only two autheriferous; filaments filiform, sometimes united by pairs at the base, or even monadelphous ; two- or sometimes one-celled, cells contiguous, parallel or superposed, or variously divaricated, occasionally one of them sterile, dehiscing longitudinally. Ovary free, dicarpellary, two-celled, the septum formed of the inflexed margins of the carpels, either complete (meeting in the axis) or somewhat incomplete ; cells anticous and posticous with respect to the axis of inflorescence, often spuriously stipitate from the obliteration of the lower half of the cells, sometimes rostrate at the apex. Ovules 1-2 or several in each cell, sessile or borne on processes of the parietal placenta ; style terminal, filiform, simple ; stigma entire or 2-lobed. Capsule 2-celled, of various consistence, unguiculate or rostrate, bursting elastically; dissepiment opposite the valves, separating in two pieces through the axis (the middle sometimes open), usually adnate to the valves, but sometimes separating from them. Seeds usually compressed, 1-2 or several in each
