. Class-book of botany : being outlines of the structure, physiology, and classification of plants ; with a flora of the United States and Canada . Botany; Botany; Botany. 02 THE FLORAL ENVELOPS, OB PEEIAMTH. 450. Exceptions. But to this, as to all other general rules, there are many- ex- ceptions. Strictly speaking, the calyx and corolla are ia no way distinguishable except by position. The outer circle is the calyx, whatever be its form or color, and the irmer, if there be more than one, is the coroUa, 451. Rules. The sepals of the calyx and petals of the corolla are, according to rule, equa
. Class-book of botany : being outlines of the structure, physiology, and classification of plants ; with a flora of the United States and Canada . Botany; Botany; Botany. 02 THE FLORAL ENVELOPS, OB PEEIAMTH. 450. Exceptions. But to this, as to all other general rules, there are many- ex- ceptions. Strictly speaking, the calyx and corolla are ia no way distinguishable except by position. The outer circle is the calyx, whatever be its form or color, and the irmer, if there be more than one, is the coroUa, 451. Rules. The sepals of the calyx and petals of the corolla are, according to rule, equal in number and severally disconnected save \>y the torus on which they stand. 452. RBteEMDLANCES. The sepals more nearly resemble true leaves in texture and color ; but the petals in form. Both have veins and re- tain more or less the same venation which characterizes the grand di- vision to which the plant belongs (§ 258). 453. Parts. Both blade and petiole are distinguishable in the floral leaves, especially in the petals. The blade or expanded part is here called limb or lamina ; the petiolar part, when narrowed into a stalk, is called the claw. 454. Nature of the sepals. The sepals are more generally sessile, like bud-scales, and appear to represent the leaf-stalk only, with margins dilated like a sheathing petiole. In confirmation of this view, we find in some flowers, as the paeony and rose, the lamina also developed, but smaller than the petiolar part. 455. Forms of petals. In form or out- line there is a general resemblance between the limb and the leaf. It is ovate, oval, lanceolate, obcordate, orbicular, etc. In margin it is generally entire. Some peculiar forms, however, should be noticed, as the bilobate petal of the chickweed, the pinna- tifid petal of miterwort, the inflected petal of the UmbeliferjB, the fan-shaped petal of •pink, the fringed (fimbriate) petal of cam- pion (silene stellata), the hooded sepal of Napellus, the saccate petal of Calceolaria, C
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