CALYCIFLOR^ 205 



6000 and 7000 species. Because it is a very large 

 Order it is divided into three Sub-Orders, of which 

 the first is cosmopolitan and the other two are tropical 

 and extra-tropical. 



Sub-order i. Papilionacece. — Flowers irregular. 

 Corolla papilionaceous or vexillary. Stamens usually 

 10, diadelphous (9 + i), that is, 9 form one bundle, 

 situated anteriorly, and i remains free, situated pos- 

 teriorly (see fig. 97) in the cleft on the upper side of 

 the bundle, occasionally monadelphous. Most of the 

 climbing Papilionacece are twiners. The brightly- 

 coloured papilionaceous flowers are often clustered 

 together into very conspicuous inflorescences admir- 

 ably adapted to attract insects, especially bees. The 

 ample pendulous racemes oi Amlierstia nobilis, often 

 planted, are the most showy of the Papilionacece . 

 Fragrance often adds to their attraction. The vexillum 

 covers and protects the inner parts in unopened flowers 

 and acts as a signboard in the open ones, and often 

 has nectar-guides. The alag are the resting-places 

 for the visitors, and act as levers depressing the keel 

 during insect-visits, so that the stigma and anthers, 

 which are kept hidden within the keel, are exposed 

 and brought into contact with the under sides of the 

 visitors. After the departure of the visitors the alas 

 rise and the keel regains its place with regard to the 

 stigma and anthers. The keel is also protective, 

 sheltering the stigmas and pistil from rain and un- 

 bidden guests. The ovary is enveloped by the sheath 

 of filaments, and the curved-up bearded style with 

 the stigma projects beyond the anthers, so that the 

 stigma first projects out of the keel when an insect 

 visits the flower and first touches its belly. A bee 

 visiting different flowers of the same species thus 

 brings about cross-pollination. The pair of slits by 



