Fig. 120.—Regular peloria, Eccremocarpus scaber.
A solitary flower of Pedicularis sylvatica was found by the Marquis of Stafford near Dunrobin Castle in Sutherlandshire, in which the usual ringent form of the corolla was replaced by the form called salver-shaped. There were six stamens, four long and two short. Sir W. Hooker and Mr. Borrer are stated to have found a similar flower in the same locality in 1809.[226]
The passage of ligulate to tubular corollas among Compositæ is not of such common occurrence as is the converse change. I owe to Mr. Berkeley the communication of a capitulum of a species of Bidens, in which there was a transition from the form of ligulate corollas to those that were deeply divided into three, four, or five oblong lobes. These then were instances of regular peloria.
Fig. 121.—Flower of Cattleya marginata. Lip replaced by a flat petal.
In Orchidaceæ a similar change is not by any means infrequent; in a few, indeed, a regular flower is the normal character, as in Dendrobium normale, Oncidium heteranthum, Thelymitra, etc. Fig. 121, reduced from a cut in the 'Gardeners' Chronicle,' 1854, p. 804, represents an instance of this kind in Cattleya marginata.
From the same journal the following account of a case of peloria in Phalænopsis Schilleriana is also cited as a good illustration of this peculiar change. The terminal flower differed entirely from all the others; instead of the peculiar labellum there were three petals all exactly alike, and three sepals also exactly alike; the petals resembled those of the other flowers of the spike, and the upper sepal also; but the two lower sepals had no spots, and were not reflexed as in the ordinary way: thus, these six parts of the flower were all in one plane, and being close together at their edges, made almost a full round flower; the column and pollen-glands were unaffected. Professor Reichenbach also exhibited at the Amsterdam Botanical Congress, of 1865, a flower of Selenipedium caudatum with a flat lip.
M. Gris[227] has placed on record some interesting cases of peloria of this kind in Zingiber zerumbet; in the more complete forms the andrœcium or staminal series was composed of six distinct pieces, the three inner of which were fertile, while in the ordinary flower the andrœcium is composed of two pieces, "a lip" and a fertile stamen. "Is it not a matter of regret," says M. Gris, "to be obliged to call the latter the normal flower?"
Under this head may likewise be mentioned those cases in which the normal, or at least the typical symmetry of the flower is restored by the formation of parts usually suppressed; thus Moquin cites an abnormal flower of Atriplex[228] hortensis described by M. Fenzl as having a true calyx within the two bracts that usually alone encircle the stamens. Adanson, also cited by Moquin, found a specimen of Bocconia with a corolla. Arum maculatum has likewise been met with provided with a genuine perianth as in Acorus and other Orontiads. The unusual development of the sexual organs in diclinous flowers has been alluded to under the head of heterogamy, and other cases where the symmetry of the flower is rendered regular, by the development of parts ordinarily suppressed, will be found in the chapters relating to deviations from the usual number of organs.