LXVII.—HALORAGEÆ.
This is a small order of aquatic or sub-aquatic, herbaceous, very rarely suffruticose plants, but widely diffused, being found in every quarter of the globe. Their habit, generally, is so peculiar, that they were at one time even placed among monocotyledonous plants by some Botanists. Mr. Brown was the first to separate them as a distinct order and determine their affinities, so late as 1814. Since then all Botanists adopted his views until Dr. Lindley, in 1836, suggested that they might be reduced to a sub-order and ranged under Onagrariae, as. mentioned under that order. In this view he has been followed by Meisner and not without some
show of reason, as the points of distinction between the two are few, and some of them I think unimportant. The principal are the absence of a style, the stigmas equaling the number of the cells of the ovary, sessile and pencillate or papulose, and lastly, the seed being albuminous and pendulous in place of exalbuminous and erect or ascending. Judging from analogy, the absence or presence of a style can be of but secondary importance, so also the character of the stigma whether capitate or divided. In Trapa the seed are equally pendulous, and some true Halorageae have a sparing albumen. For these reasons I should perhaps at this time have followed Lindley's view had we not already adopted the other in our Prodromus, and my departing from it here might tend to cause confusion.
The Indian species of this order, excluding Callitrichineae, all belong to the tribe or sub-order Cercodeeœ and are referable to three genera, Haloragis, Myriophyllum, and Serpicula, species of each of which are found on the Neilgherries. Hippuris a peculiarly northern genus, has not, so far as I am aware, been yet found in India. As in the Prodromus we have confined ourselves to giving the character of the tribe Cercudeeœ, I shall here give Lindley's character of the order, or, as he views it, sub-order.
" Calyx superior, with a minute limb, petals minute, inserted into the summit of the calyx, or wanting. Stamens inserted in the same place, equal in number to the petals, or occasionally fewer. Ovary adhering inseparably to the calyx, with 1 or more cells ; style none ; stigmas equal in number to the cells, papulose, or pencil-formed ; ovules pendulous ; albumen fleshy ; embryo straight, in the axis ; radicle superior, long and taper; cotyledons minute. Herbaceous plants, or under-shrubs, often growing in wet places. Leaves either alternate, opposite, or whorled. Flowers axillary, sessile, occasionally monœcious or diæcious."
Affinities. These have been already sufficiently explained.
Geographical Distribution. Europe, North America, Africa, India, China, Japan, New Holland, and South Sea Islands, all claim representatives of this order, though the whole number of species described by DeCandolle only amounts to 38, and probably at this time not more than 50 exist in herbaria, another instance of the often observed fact, that families of plants, peculiarly aquatic in their habits, have a wider diffusion, in proportion to the number of species, than others altogether terrestrial.
Properties and Uses. None of any importance have yet been discovered.
EXPLANATION OF PLATE 102.
Myriophyllum intermedium.
1. Flowering plant — natural size.
2. A male flower.
3. The same opened to show the insertion of the stamens.
4. A stamen.
5. A bisexual flower.
6. Fruit — in situ.
7. The same detached.
8. Cut transversely.
9. A detached carpel.
10. The same split open showing the pendulous seed.
11. Embryo detached from the albumen.
12. A cluster of flowers in situ.
13. A leaf — all more or less magnified.
TR. CERCODIANÆ. HALORAGEÆ..jpg)
MYRIOPHYLLUM INTERMEDIUM (DC.)