265. =Labiate Corolla= (Fig. 256-258), which would more properly have been called _Bilabiate_, that is, two-lipped. This is a common form of gamopetalous corolla; and the calyx is often bilabiate also. These flowers are all on the plan of five; and the irregularity in the corolla is owing to unequal union of the petals as well as to diversity of form. The two petals of the upper or posterior side of the flower unite with each other higher up than with the lateral petals (in Fig. 256, quite to the top), forming the _Upper lip_: the lateral and the lower similarly unite to form the _Lower lip_. The single notch which is generally found at the summit of the upper lip, and the two notches of the lower lip, or in other words the two lobes of the upper and the three of the lower lip, reveal the real composition. So also does the alternation of these five parts with those of the calyx outside. When the calyx is also bilabiate, as in the Sage, this alternation gives three lobes or sepals to the upper and two to the lower lip. Two forms of the labiate corolla have been designated, viz.:-- _Ringent_ or _Gaping_, when the orifice is wide open, as in Fig. 256. _Personate_ or _Masked_, when a protuberance or intrusion of the base of the lower lip (called a _Palate_) projects over or closes the orifice, as in Snapdragon and Toad-Flax, Fig. 257, 258. [Illustration: Fig. 263. Corolla of a purple Gerardia laid open, showing the four stamens; the cross shows where the fifth stamen would be, if present.] [Illustration: Fig. 264. Corolla, laid open, and stamens of Pentstemon grandiflorus, with a sterile filament in the place of the fifth stamen, and representing it.] [Illustration: Fig. 265. Corolla of Catalpa laid open, displaying two good stamens and three abortive ones or vestiges.] 266. There are all gradations between labiate and regular corollas. In those of Gerardia, of some species of Pentstemon, and of Catalpa (Fig. 263-265), the labiate character is slight, but is manifest on close inspection. In almost all such flowers the plan of five, which is obvious or ascertainable in the calyx and corolla, is obscured in the stamens by the abortion or suppression of one or three of their number. [Illustration: Fig. 266. Two flower-heads of Chiccory.] [Illustration: Fig. 267. One of them half cut away, better showing some of the flowers.]