BRACTS AXD FLORAL LEAVES. 



37 



there may be a petaloid calyx, as in anemone and marsh-marigold, 

 or no perianth at all, e.g., willow. 



Fig. 39.— Floral Leaves of White Waterlily. 

 c. sepal ; p. petals ; e. stamens. 



Fig. 40.— Flower of Hose. b. 

 bract ; et. cup-like receptacle ; 

 cf. sepals ; p. petals ; e. sta- 



The corolla and calyx, when arranged in whorls, are usually 

 isomerous, i.e., they contain an equal number of members, which, 

 in this case, regularly alternate with one another. When petals 

 and sepals are unequal in number, the former are sometimes 

 more numerous (e.g., poppy, petals four, sepals two), sometimes 

 less so (e.g., monkshood, petals two, sepals five). 



The terms hypogynous, perigynous, and epigynous (cf. p. 81) 

 are applied to the corolla specially, as well as to the flower as a 

 whole. 



Prcejloration or arrangement of leaves in the flower-bud equally 

 concerns both divisions of the perianth. 



Cohesion. — When the petals are free and distinct, as in rose, 

 buttercup, and wallflower, the corolla is polypetalous or apopetalous 

 (fig. 40). Frequently, however, there is more or less union, with 

 formation of a tube, cup, or the like, as in the gamopetalous or 

 synpetalous corollas of primrose, Canterbury bell, snapdragon, and 

 convolvulus. 



Adhesion. — The commonest union is one between corolla and 

 stamens, which will be mentioned later (p. 95). Compare also 

 p. 84. 



External Characters. — The very greatest variety is developed 

 in the corolla, which, as a whole, may be radially symmetrical, 

 bilaterally symmetrical, or asymmetrical. The individual petals, 

 when free, can, like sepals, be described in the same terms as 

 foliage leaves. They are usually narrowed at their attached end, 

 and, not infrequently, as in the pink (fig. 41), there is a distinc- 

 tion between stalk and blade, termed in this case claw and limb. 

 There may be, e.g., in ragged-robin and red campion, a small out- 



