Geographical Distribution. This order has a wide range, Europe, Africa, Asia and America, have indigenous species, one only, however, and that the common European Lythrum Salicaria has been found in New Holland. In India they abound, no fewer than 24 being already enumerated as belonging to the Peninsular flora, exclusive of two species of Ceratophyllum which most Botanists now remove from this order. These are distributed under 8
genera, the most prominent of which, as regards the number of species, is certainly Ammannia, but by far the most conspicuous as regards the species themselves are Lagerstraemea and Grislea, while Lawsonia is more common and much admired on account the fragrance of its flowers.
Properties and Uses. These are with few exceptions unknown or unimportant. Some species are astringent. The flowers of Grislea tomentosa mixed with Morinda are used to dye red. The leaves of Lawsonia alba have the property of staining the skin and nails of a deep orange colour, and are constantly employed by the natives for that purpose. It is much cultivated as a fence perhaps as much on account of the fragrance of its flowers, as for its fitness in other respects for the purpose for which it is ostensibly employed.
The Lagerstraemias are all trees or shrubs and remarkable for the beauty of their flowers. L. reginae is the most conspicuous, but L. parviflora and microcarpa perhaps the most beautiful when in flower. The only species of Ammannia, deserving notice is A. vesicatoria, Roxb. the leaves of which are so acrid that when bruised and applied, like a cataplasm, to the skin they very quickly blister it. When bruised they exhale a strong muriatic odour which is the best mark by which to distinguish the plant, but unfortunately is only applicable to the recent state.
Remarks on Genera and Species. This sub-order divides itself into two sections, Lythreae and Lagerstraemiae. The former of these is widely distributed the latter are almost entirely tropical. Of the first division 7 genera are enumerated in the Peninsular flora : of these, Rotala, Ammannia and Nescea are very imperfectly distinguished by the characters now assigned to them though they afford good ones. In the llthand 12th number of my Icones under plate 217, will be found an attempt to remodel these genera. According to the plan there sketched the pentandrons species of Ammannia are united with Rotala on account of the uneven number of their petals, stamens, and cells of the ovary: Ammannia, is limited to those species of the present genus having 4 petals, 4 stamens, and a 2-celled ovary : those having 4 stamens, 4 petals, a 4-cleft calyx, without accessory teeth and a 4-celled ovary, form a new genus under the name of Mirkooa: while those having twice as many stamens as petals, with half the number of cells to the ovary comprising, I believe, the whole of DeCandolle's section Dyplostemoneae I propose to refer to Nesaea.
This last, the essential character of which is to have twice as many stamens as lobes to the calyx, and ought to have half the number of cells to the ovary that it has petals, presents an anomaly not easily explained. In N. triflora I found the centre flower witha4-lobed calyx, and 4-celled ovary, while the lateral ones had a 6-lobed calyx and 3-celled ovary. Is the difference owing to the union of the parts of the flower causing a reduction of half their number ? The objection to this view is found in Ammannia octandra, all the flowers of which have 4 petals, 8 stamens, and a 4-cel!ed ovary. My solitary specimen of Nescea triflora a figure of which will appear in the 13th number of Icones, does not enable me to follow out the investigation, I am therefore constrained to leave for future enquiry the merits of the genus as here constituted, and also whether the theory proposed be tenable. Generic characters taken from the bracteal appendages I consider of secondary value as all have them more or less distinctly, some species of Ammannia, perhaps, being exceptions. Nescea certainly is not.
When I proposed the distribution here sketched I had not examined the whole order, and fear that I have committed an error with reference to Mirkooa, That it ought to be removed from Ammannia I do not entertain a doubt, but that it ought to form a distinct genus may be questioned I had not then carefully examined it, in comparison with the genus Ameletia, nor re-examined my genus Nimmonia (by mistake called Nimmoia), as I have since done aided by
