202 



FLORAL ENVELOPES — COEOLLA. 



summit of the petals in the form of a long process, as in Strophanthus 

 hispidus, where it extends for seven inches ; and at other times it ends 

 in a free point or cuspis, and the petal becomes cuspidate ; or the pro- 

 longed extremity is folded downwards or inflexed, as in Umbelliferse 

 (fig. 306), so that the apex approaches the base. If the median 

 vein divides into two, the space between, the divisions may be filled up 

 so as to leave only a slight deficiency, and thus the petal .becomes 

 emarginate ; or the deficiency may be greater, while the limb gradually 

 expands from below upwards, and its extremity becomes two-lobed, 

 so that the petal is obcordate. If the separation extends to the 

 middle, it is hifid; if to near the base, bipartite, as in Chickweed 

 (fig. 307 I). In the same way as in leaves, the venation of the petals 

 is sometimes unequal, and the cellular tissue is developed more on 

 one side than on the other, thus giving rise to an ohliqae petal. 



The limb of the petal may be flat or concave, or hoUowed like 

 a boat, cj/mfei/brm or navicular {cymha, a boat, navis, a ship), or like 

 a spoon, cochleariform (cochleare, a spoon). In the case of the navicular 

 petal, the median vein forms a marked keel. In Hellebore the petals 

 _^^__^ become folded in a tubular 

 ^Jiv^ form, resembling a horn ; in 

 ^ * Aconite (fig. 308) some of the 

 petals, p, resemble a hoUow 

 curved horn, supported on a 

 grooved stalk ; while in Colum- 

 bine (fig. 309) Violet, Snap- 

 dragon, and Centranthus, one 

 or all of them are prolonged 

 in the form of a spur, and are 

 calcarate {calcar, a spur). In 

 Valeriana, Antirrhinum, and 

 Corydalis, the spur is very 

 short, and the corolla or petal 

 is said to be gibbous (gibbus, a 

 bunch or swelling), or saccate 

 at the base. In some Borar 

 ginacese (fig. 322) there are 

 foldings at the upper part of 

 the tube of the corolla, r, forming projections concave outwardly, 

 which might be considered as small internal spurs. 



When a petal is narrow throughout, as if formed by a prolongation 



Fig. 308. Part of the flower of Aconitum Napellus, showing two irregular hora-like 

 petals, j», supported on grooved stalks, o. These used to te caUed nectaries, s, The 

 whorl of stamens inserted on the thalamus, and surrounding the pistil. Fig, 309. Single 

 spurred petal of Aquilegia vulgaris, common Columbine, formed by a folding of the 

 margins. Fig. 310. Cordate or cordiform petal of Genista caudicans. o, The claw. 

 I, The limb. 



Fig. 308, 



Fig. 310. 



