The regular development of all the parts of the flower in a plant habitually producing irregular flowers is referred to under the head of Peloria, but it still remains to consider those examples in which some only of the parts of the flower are affected in this manner.[220] Most of these cases are elsewhere referred to in this volume under the particular form of malformation assumed; but the following case may here be noticed as not coming under any of the previous heads. It is an instance recorded by Professor Babington ('Phytologist,' August, 1853), and in which the pod of _Medicago maculata_, which is usually rolled up like a snail shell and provided with spines, was sickle-shaped and unarmed.
[220] See a paper of Professor C. Morren's on "Floral Stesomy" in 'Bull. Acad. Belg.,' t. xix, part ii, p. 519.
[Illustration: FIG. 116.--Regular Peloria, _Delphinium_.]
[Illustration: FIG. 117.--Sepal, petal, &c., of regular-flowered _Delphinium_.]
[Illustration: FIG. 118--Regular peloria, _Viola_.]
[Illustration: FIG. 119--Double Violet, flower regular, petals multiplied, stamens and pistils petaloid.]
When an habitually irregular flower becomes regular, it does so in one of two ways; either by the non-development of the irregular portions, or by the formation of irregular parts in increased number, so that the symmetry of the flower is rendered perfect, as in the original peloria of Linnæus, and which may be called irregular peloria, while the former case may be called regular peloria. This latter appearance is therefore congenital, and due to an arrest of development.[221] As the true nature of these cases has not been in all cases recognised (even Moquin places them under the head of deformities--they being less entitled to rank in that class than are the usual flowers), it may be well to cite a few instances taken from various families. In _Delphinium peregrinum_ I have met with perfectly regular flowers having five sepals and five oblong stalked petals, and a similar occurrence has been noted in other species of this genus. Baillon,[222] in referring to these flowers, points out the resemblance that they bear to the double varieties of _Nigella_. In the stellate columbines (_Aquilegia_) of gardens the tubular petals are replaced by flat ones often in increased numbers. In violets both forms of peloria occur, that in which there is an unusual number of spurs, and that in which there are no spurs (var. anectaria). In the more perfect forms of regular peloria occurring in the last-named genus the following changes may be noticed: 1, an alteration in the direction of the flower so that it remains in an erect position, and is not bent downwards as usual; 2, equality of proportion in the sepals and petals; 3, absence of spurs, as also of hairs on the lateral petals; 4, equal stamens whose anthers are sometimes entirely destitute of the prolonged crest which forms so prominent a feature under ordinary circumstances; 5, erect, not curved styles, and the stigmas not prolonged into a beak, but having a more or less capitate form; ovary with three or five cells, ovules normal.