Fig. 212.—Datura fastuosa. True corolla turned back to show the supernumerary corolla with the petal-like segments attached to its outer surface (reduced).
Of more interest are those instances where the adventitious growth is on the outside of the corolla; thus in a garden azalea there was intermediate between the calyx and the corolla, both of which were normal, a series of five petalodes, alternating with the sepals, and, therefore, opposite to the lobes of the corolla, and adherent with them at the very base, though elsewhere detached. These petalodes were concave on the surface looking towards the calyx, and were there brightly coloured, while the tint of the opposite surface looking towards the corolla was of a duller hue, corresponding with that of the outside of the corolla-tube. This arrangement of the colour was thus precisely similar to that which occurred in the four-winged leaves already referred to at p. 446. In some flowers of Datura fastuosa a similar series of excrescences was observed; the calyx and the corolla were normal within the latter, intervening between it and the stamens was a second corolla produced by duplication, and adherent to the inner surface of this latter were five stamens. So far there was nothing very peculiar; it remains to say, however, that on the outer surface of the second corolla were five petal-like lobes closely adherent to it below, but partially detached above. The colour of the adventitious segments was paler on the outside than on the inner surface, as in the corolla itself. The position of the several parts was such that they were opposite one to the other; hence, while the lobes of the inner corolla were opposite to those of the outer one, the intermediate petalodes were opposite to both; thus:
S S S S S
--------------------------
P P P P P
| X X X X X
|--------------------------
| P P P P P
|st st st st st
The X indicating the position of the petalodes.
Fig. 213.—Gloxinia, with supernumerary segments on the outside of the true corolla.
A still more singular case is that of a variety of the Gloxinia, described originally by Professor Edouard Morren,[521] but which is now becoming common in English gardens. When first observed these flowers were observed to produce petaloid segments outside the ordinary corolla, and partially adherent to (or rather, not completely separated from it) much as in the azalea before mentioned, the outer surface being brightly coloured, like the inner surface of the corolla in ordinary gloxinias. Being encouraged and tended by gardeners, in course of time, instead of a series of petalodes, more or less distinct from one another, a second corolla or "catacorolla" was formed outside the primary one, so that a hose in hose flower was produced, but, in this case, the supplementary flower was formed on the outside and not within the ordinary corolla. Moreover, the disposition of the colour was reversed, for in the outermost corolla the richest hues were on the outer surface, while in the inner or true corolla they were on the inside.