There are cases, however, in which a part only of the pistillary structure thus becomes foliaceous. Linnaeus, 'Prolepsis,' Sec. 9, mentions some flowers of _Carduus heterophyllus_ and _C. tataricus_ in which the style had grown into two green leaflets, and in which the calyx and corolla were also leaf-like. A very singular instance is recorded by Baillon,[265] wherein the pistil of _Trifolium repens_ consisted of three carpels, either separate, or combined so as to form a one-celled ovary with three parietal, pluri-ovulate placentae; the ovary in these flowers was formed of the basal vaginiform part of the leaf; the three styles were formed by the petioles, while the stigmas were represented by trifoliolate leaves. The back of the leaf in these cases is usually directed away from the centre of the flower. When this change occurs it is commonly attended by an increased number of parts, as in the trefoil just mentioned, or in the double cherry, where usually two foliaceous carpels may be met with, and sometimes more. The change is also of interest when it affects such orders as the _Umbelliferae_, which have their ovaries inferior under ordinary circumstances; but when these organs assume a leafy condition they become superior also, _i.e._ they are detached from the calyx. As regards the position of the ovules in these foliaceous pistils, they may be placed, as in _Aquilegia_, _Delphinium_, &c., on the edges of the carpel or on the surface, as in some flowers of _Ranunculus repens_ and _R. Ficaria_. A similar position of the ovules is recorded in the case of the vine (_Vitis_), where the pistil consisted of leaves bearing the ovules on their inner surface.[266] The supposed causes of this and other similar malformations are alluded to under the head of chloranthy, but it may be here remarked that semi-double flowers, fertilised by the pollen of similar flowers, are said to produce flowers with a centre of small green leaves, this central tuft resulting from the expansion and frondescence of the pistils. As this condition rarely occurs without corresponding changes in other parts of the flower, further remarks on this subject will be found in the chapter relating to Chloranthy. Phyllody of the pistil has been most frequently recorded in the following plants: