Tubular formations in the flower.—A similar formation of tubes happens in some double flowers; for instance, it is not infrequent in double flowers of Primula sinensis, in which tubular petal-like structures are attached to the inner surface of the corolla; sometimes these petaloid tubes replace the stamens, while at other times they appear to have no relation to those organs. In the particular flowers now alluded to the tubular form seems due to a dilatation, and not to a cohesion of the margins. (See Cohesion, p. 23.) These tubular petals resemble in form and colour almost precisely the normal corolla in miniature, but are not surrounded by a calyx, nor do they contain stamens, while the less perfect forms show clearly their origin from a single tube-like organ.
Fig. 168.—Corolla of Primula sinensis turned back to show a tubular petal springing from it. One only is shown for the sake of clearness; they are generally numerous.
The formation of spurs or spur-like tubes in a quasi-regular manner has been spoken of under the head of Irregular Peloria, p. 228, but we occasionally meet with tubular processes which seem to occur in an irregular manner, and to have no reference to the symmetrical plan of the flower, and which are due probably to the same causes as those which induce hypertrophy. Such spurs have frequently been seen on the corolla of Digitalis purpurea, Antirrhinum majus,[352] Tulipa Gesneriana, and occasionally on the sepals of Fuchsia. They are very frequent in some seasons in the corolla of certain calceolarias (C. floribunda). By Morren this production of adventitious spurs was called "Ceratomanie."
Fig. 169.—Corolla of Calceolaria, showing irregular tubular spurs projecting from the lower lip.
Similar processes may sometimes be seen in the capsules of Linaria vulgaris, as also in the fruits of some of the Solanums, quite without reference to the arrangement of the carpels, so that their production seems to be purely irregular.
Morren, as previously remarked, gave the name "Solenaidie" to tubular deformities affecting the stamens, a term which has not been generally adopted; the deformity in question is by no means of uncommon occurrence in some double or partially pelorised flowers, as Antirrhinum, Linaria, &c. A similar formation of conical out-growths may frequently be met with in the fruits quite irrespectively of any disjunction of the carpels.