In some instances hypertrophy is the opposite of suppression; as in the case previously mentioned, where the stipule in the inflorescence of a pea, which is usually undeveloped and rudimentary, was developed in the form of a leafy cup or pitcher.
Another instance of the development of parts usually suppressed, is afforded by the bud-scales of Magnolia fuscata, which may sometimes be found with small but perfect leaves projecting from them, the leaf in this case being the lamina which is ordinarily abortive, while the scales are the representatives of the stipules. This condition is said by Hooker and Thomson ('Flora Indica,' p. 73) to be constant in Magnolia Campbelli.
Enlargement of the perianth, &c.—One or all the segments of the perianth may be subjected to hypertrophy; thus, the utricle of Carex vulpina may frequently be observed to attain four or five times its usual size, the contained ovary remaining unaffected. This condition is generally the result of insect puncture. The growth of parasitic fungi will produce a similar result, as is often seen in the common shepherd's purse, Thlaspi bursa pastoris, and other Cruciferæ. The perianth of Rumex aquaticus has been also observed to be occasionally hypertrophied in conjunction with a similar condition of the pistil and with atrophy of the ovules.
Moquin relates having found flowers of Salsola Kali and of Chenopodium murale in which some of the segments of the perianth were five or six times larger than they should be.
Fig. 205.—Hypertrophy of the perianth in Cocos nucifera.
The adjoining woodcut represents a singular condition of some cocoa-nuts in the Kew Museum, the appearance of which is due apparently to an hypertrophied condition of the segments of the perianth, which have not only increased in length as the central nut has ripened, but have developed in their tissues that fibrous tissue which ordinarily is found in the pericarp only. This view of the structure of these nuts is borne out by the fact that, under normal circumstances, the base of the perianth contains a considerable amount of fibrous material. In the present case this has increased to such an extent that the fruit appears surrounded by a double husk, by an inner one as usual, and by an outer six-parted one.
It will be remembered that in some of the Cinchonaceæ, e.g. Mussænda, Pinckneya, Calycophyllum, one or more of the calycine lobes are normally dilated and petaloid, the others remaining small and comparatively inconspicuous. Inequality in size is, indeed, a common occurrence in the sepals of many natural orders—Polygalaceæ, Leguminosæ, Labiatæ, &c. The flowers of a rose are mentioned by Moquin as having presented an enlargement of the calyx without any other alterations in form. Schlechtendal has noticed the same thing in Papaver Rhœas, Reichenbach in Campanula persicifolia, and A. de Candolle in C. Rapunculus. M. Brongniart also has recorded[498] a remarkable variety of Primula sinensis cultivated in the Jardin des Plantes at Paris, wherein the calyx is enormously developed. MM. Fournier and Bonnet have described flowers of Rubus with hypertrophied calyx in conjunction with atrophy and virescence of the petals and other changes.[499]