Some of the ascidia or pitcher-like formations are due to the cohesion of the margins of two leaves, as in a specimen of Crassula arborescens, observed by C. Morren.
Fig. 10.—Two-leaved pitcher of Crassula arborescens, after C. Morren.
The stipules may also be fused together in different ways; their edges sometimes cohere between the leaf and the stem, and thus form a solitary intra-axillary stipule. At other times they become united in such a manner as to produce a single notched stipule opposite to the leaf. Again, in other cases, they are so united on each side of the stem, that in place of four there seem only to exist two, common to the two leaves as in the Hop.
To the Rev. M. J. Berkeley I am indebted for specimens of a curious pitcher-like formation in the garden Pea. The structure in question consisted of a stalked foliaceous cup proceeding from the inflorescence. On examination of the ordinary inflorescence, there will be seen at the base of the upper of two flowers a small rudimentary bract, having a swollen circular or ring-like base, from which proceeds a small awl-shaped process, representing the midrib of an abortive leaf. In some of Mr. Berkeley's specimens, the stipules were developed as leafy appendages at the base of the leaf-stalk or midrib, the latter retaining its shortened form, while, in others, the two stipules had become connate into a cup, and all trace of the midrib was lost. The cup in question would thus seem to have been formed from the connation of two stipules which are ordinarily abortive.
Cohesion of the bracts by their edges, so as to form a tubular involucre, or by their surfaces, so as to form a cupule, is not of uncommon occurrence, under natural conditions, and may be met with in plants which ordinarily do not exhibit this appearance.
Cohesion of the sepals in a normally polypetalous calyx renders the latter gamosepalous, and is not of uncommon occurrence, to a partial extent, though rarely met with complete. I have observed a junction of the sepals to be one of the commonest malformations among Orchids, indeed such a state of things occurs normally in Masdevallia Cypripedium, &c. An illustration of this occurrence is given by Mr. J. T. Moggridge in Ophrys insectifera, in 'Seemann's Journal of Botany,' 1866, p. 168, tab. 47. In Orchids, this cohesion of sepals is very often co-existent with other more important changes, such as absence of the labellum, dislocation of the parts of the flower, &c.
