82
ILLUSTRATIONS OF INDIAN BOTANY.
plants have no leaves, but stipules only, for in that and similar Orders the apparent leaves are never opposite the angles of the stem, but are always placed between them. Nor do I find that the number of angles in the stern of verticillate plants necessarily corresponds with the number of their leaves ; for example, in Dysophylla stellata, where the whorls often consist of ten parts, the stem has still but four angles. Neither can it be admitted that bodies which do not form branches in their axils are therefore not leaves. All foliaceous organs, of whatever kind, and especially stipules, possess that power or not, according to circumstances, as is too well known to require particular proof. Besides, DeCandolle's statement is not sustained by fact ; for in Asperula the uppermost branches, bearing flowers, are frequently produced alternately with the leaves that form the node from which they spring, and consequently must, in such cases, arise from the seat of one of the supposed stipules. It is more probable that the development of branches from a portion only of the leaves, is connected with the form of the stem, and the relation which the leaves bear to each other. If the form of the stem requires an alternate developement of a pair or a triplet of opposite branches, then the first whorl in which the development takes place, will settle the origin of all that succeed it. For example, if in one whorl of six leaves, the first, third, and fifth leaves produce axillary buds, then in the whorl next above it, the second, fourth, and sixth leaves will probably be gemmiferous, according to the ordinary laws of decussation. It is plainly impossible to say that what seem to be leaves are in reality stipules, because they have no axillary buds; for if that opinion were maintained, it would be necessary to assign the quality of stipules to a certain portion of the leaves of such verticillate plants as Dysophylla stellata, in which only a part of the whorls ever produces branches.
2. If it is true that in Asperula two opposite leaves are frequently longer than the others, that circumstance may be reasonably ascribed to the greater development conse- quent upon their higher functions, and to their peculiar position on the stem ; and it is equally true that in the greater part of Stellates no trace whatever of any kind of difference between the leaves can be detected, as is most remarkably the case in those surrounding the flowers of Crucianella maritima.
3. The argument derived from the occasional connection of the leaves by a membrane can hardly be allowed much weight, when it is remembered that in such cases the inter mediate leaves are less like stipules than in those cases where no membrane exists ; com- pare Asperula cynanchica, or litteralis, or longiflora, with such genuine Crucianellas as C. maritima.
4. The comparison of the supposed stipules of Stellates and the setae of Spermacoceae is inadmissible, because the former are at all events single, simple organs, be they what they may, while the setae of Spermacocea? are the result of the splitting of two parallel- veined stipules, and therefore will necessarily be uncertain in number.
These arguments do not, however, by any means exhaust the question ; and therefore I proceed to make a few additional remarks upon a point not yet adverted to. It is in Asperula, more than in any other genus of the Order, that is to be found evidence favourable to the supposition of M. DeCandolle, and his followers. In A. longiflora, cynanchica, and some others, the lower whorls are in the usual state, but the upper ones are reduced to two perfect leaves, with one or sometimes two teeth or subulate processes between them, which remain. In this condition the structure of Asperula is so very like that of many Spermacoceous plants, that the analogy between them seems indisputable; and I presume that it was such cases which first led to the theory under consideration.
It is, however, to be remembered, that in Stellates the supposed stipules are always what first disappear in the process of reduction in the number of foliaceous appendages ; but that in Cinchonads it is in many cases the leaves which are first lost when such a reduction takes place. The latter fact is readily verified upon reference to any of the capitate Sper- macoces, where the bracts are evidently stipules, and especially to S. calyptera, in which the leaves are gradually merged in the large membranous cup that subtends the flowers, while the stipules suffer no diminution. The same circumstance may be observed in several Brazilian Cinchonads allied to Psychotria barbiflora, and in Pasderia foetida. It is also pos-
