FLORAL ENVELOPES. COROLLA. 177 



seen in the petals of the Pink (fig. 281), where o is the claw, and I 

 the limb. The claw is often wanting, as in the Rose, and the petals 

 are then sessile. Those having a claw are ungui- 

 culate. 



371. Petals, properly so called, belong to Exo- 

 genous plants, for in Endogens the flowers consist of 

 a perianth or perigone, which is referred to the caly- 

 cine envelope. Hence the venation of petals resem- 

 bles that of exogenous leaves. In the claw the 

 vessels are approximated, as in the petiole, and in 

 the limb they expand. There may be a median 

 vein whence lateral veins go off, at the same or dif- 

 ferent heights, forming reticulations; or there may 

 be several primary veins diverging from the base 

 of the limb, and forming a sort of fan-shaped vena- 

 tion. At other times the median vein divides into two. 



372. According to the development of veins, and the growth of 

 cellular tissue, petals present varieties similar to those already noticed 

 in the case of leaves. Thus the margin is either entire or divided 

 into lobes or teeth. These teeth sometimes form a regular fringe 

 round the margin, and the petal becomes fimbriated^fimbria?, a fringe), as 

 in the Pink (fig. 281); or laciniated, as in Lychnis Flos cuculi ; or crested. 

 as in Polygala. The median vein is occasionally prolonged beyond 

 the summit of the petals in the form of a long process, as in Strophan- 

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

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

 longed extremity is folded downwards or inflexed, as in Umbellifera? 

 (fig. 282), so that the point approaches to 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 be- 

 comes obcordate. If the separation extends 

 to the middle, it is bifid; if to near the 

 base, bipartite, as in Chickweed (fig. 283 I). 282 

 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 oblique petal. 



Fig. 281. An unguiculate petal of Dianthus monspessulanus. o, Unguis or claw. I, Limb 

 which is nmbriated, or has a fringed margin. 



Fig. 282. A petal of Eryngium campestre, with the apex inflected or turned down towards 

 the base. 



Fig. 283. A bipartite petal of Alsine Media, or common Chickweed. I, The limb split into two 

 o, The claw. 



N 



