Page:Illustrations of Indian Botany, Vol. 1.djvu/419

ILLUSTRATIONS OF INDIAN BOTANY.

207 

1 . Lawsonia alba — natural size.

2. An expanded flower ise o from above.

3. Stamens back and front views.

4. The ovary.

5-6. Cut transversely and vertically.

7. The fruit nearly mature— natural size.

8. The same cut transversely.

9. A seed somewhat winged.

10. The same cut transversely.

1 1. Cut vertically, showing; the embryo in situ.

12. Embryo detached — with the exceptions mentioned, all more or less magnified.

1. Lagerstraemia indica, flowering branch — natural size.

2. A dissected flower.

3-4. Anthers back and front views.

5. Stigma.

6- 7. Ovary cut vertically and transversely, 6-celled, with the ovules collateral.

8. A fruit not quite mature.

9-10. Horizontal and vertical sections of the same.

11. A seed — natural size.

12-13. The same magnified and opened, to show the position of the aeed.

14. A detached seed.

15. The embryo removed from the testa, cotyledons foliaceous, convolute — with the exceptions mentioned, all more or less magnified.

 

This is a small, hut widely diffused order, growing on salt swamps and marshes on the sea coasts of nearly all tropical countries, constituting the mangrove tribe, so noted for the unwhole- some climate which often prevails where it is very abundant, apparently, through the dense mass of vegetation which it produces intercepting the sun's rays, and maintaining a constant exhalation of noxious vapour from about their roots. Like the Banyan ( Ficus indica J and the Caldera, ( Pandanus odoratissimvs J most of the species send down roots from the stem and branches, by means of which they rapidly spread themielves to a great extent. Another very remarkable peculiarity of this family is the unique manner in which its seed germinates; here germination takes place not as in other plants after the shedding of the seed, but before it has left the seed vessel. After the seed has attained maturity its rhdicle and club-shaped tigillus gradually elongates until it either enters the soft muddy soil in which the tree grows, or if more elevated it drops and fixing itself in the muddy bottom immediately strikes root at the one end while the leaves begin to develope themselves at the other. The species are all trees or shrubs with opposite coriaceous simple entire leaves, sometimes, in Carallia, dentate, usually tapering towards the petiol and furnished with interpetiolar convolute caducous stipules. The flowers are bi sexual, regtdar, axillary, congregated in few or many-flowered cymes. Dr. Arnott in an excellent memoir on the order published in the Annals of Natural History, vol. 1st, has given a detailed character of the Linnaean genus Rhizophora, but which he thinks ought rather to be considered a group or sub-order, of Rhizophoreae, as containing several distinct genera. The group may be called Rhizophoroe, he defines it as follows.

" Calyx 4- 14 cleft, persisting: aestivation valvate. Petals sessile, 4- 14, inserted into the calyx and alternate with its lobes. Stamens 8 or more, inserted with the petals : filaments dis- tinct, anthers 2-celled, dehiscing within. Disk fleshy between the ovary and calyx, occasionally forming a short toothed ring between the stamens and ovary. Ovary more or less cohering, 2-4-celled, cells 2-ovuled, ovules pendulous from the apex of a central axis. Style simple. Stigma 2-4, dentate or simple. Fruit coriaceous, 1 -celled, I -seeded, after germination has commenced perforated at the apex, by the extension of the radicle and tigillus of the embryo into a long club. Albumen none. Cotyledons flat, radicle superior."

This character does not include Carallia, the seed of which do not germinate in the pere- carp, but with that exception, the character applies to it also.

This order differs from all others in the remarkable property of its seed germinating before they have left the tree. The structure and dehiscence of the anther in Rhizophora is also very peculiar. In place of as usual consisting of two parallel cells opening either by pores at the apex or by slits, it seems to consist of a solid central axis, the surface of which contains numerous fovioli containing the pollen and covered by a membrane, when mature 