178 SOUTH AFRICAN BOTANY 
Type.—Lupinus (the Lupin). These are common 
herbaceous annuals, cultivated for their showy flowers. 
Inflorescence.—A. raceme. 
Flower.—Zygomorphic, complete, bracteate, pedicel- 
late. 
Calyx.—Gamosepalous, 5, inferior. 
Corolla.—Papilionaceous, polypetalous, 5, perigynous. 
The upper petal is the Standard, the two side ones 
are the Wings and the two lower are united to form the 
Keel. 
Androecium monadelphous, 10 perigynous; Fila- 
ments united at base, free above, 4 being longer than 
the other 6; Anthers basifixed, 2 lobed, introrse. The 
anthers of the shorter stamens are larger than the others. 
Gynoecitum.—Monocarpellary, superior. Stigma ter- 
minal and small, style curved; ovary long and hairy, 
one-celled, ovules numerous, placentation marginal. 
Fruit.—A legume which bursts open when ripe and 
jerks out the seeds, the 2 halves of the pericarp twisting 
spirally. 
Pollination—The stigma is only receptive when 
rubbed, so the flower has a good chance of cross-pollina- 
tion. The pollen is shed into the keel. When insects 
visit the flower they cling on to the wings; this de- 
presses the keel and the pollen is forced out of the little 
opening at the tip of the keel by means of the shorter 
stamens which have swollen filaments and act as a kind 
of piston. When the insect leaves, the keel springs 
back to its former position—thus four or five visits may 
be made to the same flower, and cross-pollination is 
practically certain. 
