THE FL0RA1 ENVELOPS, OR PERIANTH. 



450. Exception's. But to this, as to all other general rules, thero are many ex- 

 ceptions. Strictly speaking, the calyx and corolla are in no way distinguishable 

 except by position. The outer circle is the calyx, whatever be- its form or color, and 

 tho inner, if thero bo more than one, is the corolla. 



451. Rules. The sepals of the calyx and petals of the corolla are, 

 according to rule, equal in number and severally disconnected save by 

 the torus on which they stand. 



452. Resemblances. 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 bo noticed, as the 

 bilobatc petal of the chickweed, the pinna- 

 tifid petal of miterwort, the inflected petal 

 of the Umbeliferse, 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, 

 Cypripedium. 



456. Nectary. The limb is, moreover, 

 often distorted into a true nectary, spurred, 

 as already shown (§ 434), or otherwise de- 

 formed, as in Napellus, Coptis, etc. 



Forms of petals. 204, Butter- 

 enp, showing the scale at base. 



295. Mignonette, fringed at top. 



296, Silene stellata. fringed and 

 unguiculate. 297. Flower of 

 Osmorhiza longistylis, petals in- 

 flected. 299, Flower of Mitella 

 diphylla. petals pectinate-pinna- 

 tifll. 299, Petal of Cerastium 

 nutans, 2-clcft. 



