THE FLORAL ENVELOPES COROLLA. 



Ill 



Aconite (fig. 188) is an example of this ; and a still more important case 

 occurs in the papilionaceous corolla of Leguminosce (figs. 191-193), which 

 is composed of five petals, of which the posterior, the vcxillum (fig. 192, a) 

 or standard, the largest, usually symmetrical in form, is placed trans- 

 versely ; the two lateral (fig. 192, b, 6), mostly oblique in form and small, 

 forming the alee or wings, stand right and left, with the edges fore and 

 aft ; and the two anterior (fig. 192, c, c), also small and oblique, often 

 coherent in front, and forming the carina or keel, also stand with their 

 edges forward. 



Fig. 188. 



Fig. 190. 



Fig. 189. 



Pig. 188. Flower of Aconitum with the sepals removed, showing the two hammer-headed 

 posterior petals (or nectaries), with lateral and anterior scale-like petals, outside 

 the numerous stamens. 



Fig. 189. Bilabiate scroll-like petal (or nectary) of Helleborus. 



Fig. 190. Floret of Composite, with inferior ovary surmounted by scaly pappus and tubular 

 corolla. 



Examples occur in the large order Leguminosse of almost every modi- 

 fication of the papilionaceous corolla, approaching to regularity in Baptisia 

 for instance, and still more in Cassia. Irregular corollas exist also in the 

 Fumariacese, in Viola, B.ilsaminacese, Pelargonium, Tropceolum, and very 

 manv other plants. 



Fig. 191. 



Fig. 191. Papilionaceous corolla of Pea. 



Fig. 192. The separated petals : a, vexillum ; ft, I, alae ; c, c, carina. 



Fig. 193. Ground-plan of floral envelopes, showing the coherent sepals and aestivation of the 



petals. The central line shows that the flower may be symmetrically divided into 



two equal halves. 



