[Illustration: FIG. 130.--Fuchsia, with one of the sepals leaf-like.]
De Candolle[256] figures a curious instance wherein the pappus of _Podospermum laciniatum_ was replaced by five linear, foliaceous lobes. A similar change has been noticed in other composites, as in _Tragopogon pratense_. Engelmann mentions as subject to this hypertrophy of the pappus, as it may be termed, _Scorzonera octangularis_ and _Senecio vulgaris_. Wigand has observed a similar transformation in a species of _Centranthus_ (_Valerianaceæ_).
In some cases the phyllody of the sepals has a special interest, as bearing on the question whether what is termed calyx-tube is or is not a portion of the calyx, and whether the sepals are modifications of the blade or of the sheath of the leaf. Thus in the primrose the phyllodic sepals seem to show clearly that the sepals are in that plant of a laminar nature (fig. 131). The so-called calyx-tube of roses is elsewhere alluded to. The leaf-like organs sometimes seen at the apex of a cucumber would seem to support the view that there was really a calyx-tube in _Cucurbitaceæ_ adherent to the carpels. It is also shown in the cut, fig. 132, borrowed from the 'Gardeners' Chronicle,' 1859, p. 654.
[Illustration: FIG. 131.--Primrose. Calyx of foliaceous segments.]
[Illustration: FIG. 132.--Leafy calyx of melon.]
Under ordinary circumstances, the sepals may be considered as the representatives of the sheath of the leaf (cataphyllary) or of the blade (euphyllary), the arrangement of the veins being different in the two cases; thus, in the vagina or sheath, there are generally several large veins of about equal size, either convergent towards the apex, or divergent; on the other hand, in the blade, there is usually but one central vein, the midrib, larger than the rest, and the smaller veins come off at a less acute angle, and are more reticulated.[257]
Now, when phyllomorphy occurs in sepals which ordinarily are vaginal, it is obvious that the case is one, not merely of increased relative growth, but also of the appearance or development of an organ habitually suppressed; on the other hand, when phyllomorphy occurs in sepals which usually are laminar in form and nervation, the case is one of unusual growth or hypertrophy, and not of the development of an organ habitually suppressed, so that the amount of change is greater in the former than in the latter instance.