I am unaware whether this explanation has occurred to any body else.
It is curious as compared with Scitamineæ, in which the posticous stamen is alone fully developed. Pl. 1. Fig. 3. a. bracteoid body, b. sterile stamen, c.c.c. outer series, d.d. inner ditto.
The fact of the outer smaller laciniæ belonging to a second series is not very apparent, but is corroborated by the evidently internal situation of the bracteoid scale, and by the evidently elevated lines visible in the inner.
(April 3rd, 1837.—On march towards the Serpentine mines) the face of the perianth, corresponds to these smaller laciniæ.
April 7th.—Thunbergia grandiflora has the pedicels of its flowers twisted, or not twisted, according to the situation of the flowers. Thus if the flower be so situated that the raceme has the direction of the axis, or in other words is erect, the pedicel is straight, but if the raceme, as generally happens, be pendulous, the twisting of the pedicel is resorted to, to secure the flower that situation which it would have, were the raceme erect.
The above is obvious in flowers which from elongation of the axis of inflorescence, have fasciculate or aggregate flowers. An obvious inference is, that the twisting of the pedicel is not of generic, nor of specific importance; and that it is capable of being produced artificially.
This resupination is not uncommon in the order; it is most evident in Thunbergia coccinea, in which the racemes are always pendulous. There is nothing, at least in this species, in the situation of the genitalia to account for the resupination.
Pedicelli demum apicem infra articulati, the inflorescence of this order is always centrifugal, the partial axis being invariably as well indeed as the general, disposed to dichotomy. Hence the very common presence of three bracteæ to each flower, the central one presenting the leaf from whose axil the partial branch springs.
Stipulæ—if the analogy of these be difficult to ascertain, the structure and functions would appear to be as of leaves, in addition to the function of protection. In most cases they are certainly not double organs; in Naucleaceæ they are apparently so. Can this be explained by supposing them to form a bud with four scales, the scales instead of being imbricate, being on one plane. Stipellæ of Leguminosæ are certainly single; these being all probably stipulate plants, are to be considered as having terminal buds, the buds being either totally, or partially protected by the stipulæ. The difficult nature of ochreæ of Polygoneæ is certainly to be acknowledged, but they are similar to those of Costus, and hence not stipulæ, but an extension of the margin of the vaginate petiole, from which veins are prolonged into it; the functions of these are not stomatose, since they are membranous, the veins being the only green parts.
I see no reason why the stipulæ of Rosæ are not to be considered as belonging to, or dilatations of the petiole. They have no distinct vascular fascicles to indicate a distinct origin. And further, in Lowea no stipulæ exist.