66 NEILGHERRY PLANTS. 
at the point of insertion; the flowers are spicate and each furnished with 3 bracts from 
the axil of which it springs. The exterior bracts are often large and foliaceous but some- 
times reduced to a small size and ending in a subulate point ; the flowers are always more 
or less irregular, the corolla being sometimes nearly regular but the stamens only two or 
four; in others the corolla is very irregular being ringent, or two-lipped, or one-lipped. 
The stamens vary in number and size, being two or four, frequently with the rudiment ofa 
fifth which has aborted, showing that were the flowers regular they should have 5 stamens. 
The anthers, too, vary; they are sometimes normal, that is, the 2 cells are side by side, 
at others the two are separate, or one is imperfect and converted into a spur; occasionally, 
as in Andrographis, they are furnished with a tuft of hairs; but the most remarkable 
feature of the family is found in the seed-vessel which is composed of 2 valves, and within 
furnished with hooked processes to which the seed are attached. The valves open with 
elasticity (scattering the seed) through the middle of the partition which adheres to the 
valyes, forming a ridge along the middle of each. The capsule is formed of 2 carpels, or 
modified leaves, the edges of which are inflexed and more or less perfectly meet in the 
centre, forming a 2-celled capsule, but sometimes there is a division between them. The 
dehiscence or mode of opening, therefore, of the capsule of this family, is what Botanists 
call “Loculicidal,” or through the middle of cells, in contradistinction to “ Septicidal,” 
through the middle of the septum or partition, as is the case with many plurilocular cap- 
sules. By this mark their relationship to Bignoniacee is made out, many of the species of 
which have loculicidal dehiscence, but in others it is septicidal. This difference is made 
use of to divide that family into two principal divisions. When a nearly ripe capsule can 
be obtained there is no difficulty in determining the order of any Acanthaceous plant, as 
this kind of dehiscence is constant throughout the family. The seed is variable, sometimes 
smooth, sometimes rough, and hairy, generally flattened, but sometimes orbicular, but in 
all without albumen. 
The order, as already stated, is a very large one, including, according to Nees’ enu- 
meration, 155 genera and about 1500 species. Sometime previous to the publication of 
Nees’ monograph, Lindley gave 105 genera and 750? species as the probable numbers. 
The history of the order is curious. When first defined by Jussieu, in 1789, seven genera 
included all the then known species. To these Brown and Willdenow made several addi- 
tions, but in 1830 they, according to Bartling, only amounted to 20. In 1832-33, Nees 
Von Esenbeck raised the number, appertaining to India alone, to 56. In 1840, Endlicher 
gave extended generic characters of 80. In 1847, Nees’ monograph was published in 
De Candolle’s Prodromus, and raised the number to 155 and about 1500 species. Since 
then considerable additions have been made to the species, and a few to the genera. Of 
genera, the number is excessive, many of those based on distinctions of scarcely generic 
value, and some on defective observation; the same may be said of some of the species, 
leading to the inference that the article was hurriedly finished, but notwithstanding these 
detects, the monograph is truly an excellent one, and worthy of the excellent Botanist who 
wrote it. Being a very difficult order, I have thought it advisable to illustrate it fully, and 
have, with that view, published in my Icones figures of about 100 species. 
Its geographical distribution is extensive within the tropics, and the warmer regions 
= either side, Asia, Africa, and America all furnishing numerons species; Australia also 
contributes pretty liberally to the store, and even Europe is not altogether destitute, the 
genus Acanthus:being found in Greece. With this marked predilection for heat it seems 
curious that they should so abound on the highest mountains. All the largest and finest 
