6 BULLETIN 289, U. S. DEPARTMENT OF AGRICULTURE. 
not oeciipied by the vexillum. Even though the base of the carina 
is narrow it is able to return to its normal position shortly after being 
bent downward. The alz are attached by their flexible claws to the 
common tube. Before a flower opens the ale are pressed closely to 
the carina, although as the flower matures they spread apart. The 
staminal tube splits superiorly to admit the tenth free stamen. The 
filament of this superior stamen lies along the side of the staminal 
tube and therefore does not interfere with the proboscis of a bee 
which is inserted to collect nectar. Nectar is secreted at the bases 
of the stamens and accumulates in the staminal tube around the base 
Fig. 1.—Different parts of a red-clover flower: 1, Anterior view of flower; 2, posterior view of flower after 
the vexillum has been removed; 3, posterior view of flower, showing the carina, which has been forced 
apart (twice the magnification of the other drawings); 4, right ala, from within; 5, right half of carina, 
from without, the claws of 4 and 5 having been partly broken off; 6, the essential organs emerging from 
the depressed carina; 7, longitudinal section of a flower. a,Calyx; 6, tube formed by the partial union 
of 9 filaments with the claws of the vexillum, ale, and carina; c, vexillum; d, concave part of the inner 
side of ala; e, lower border of ala, bent outward; f, outward surface of ala; g, pouched swelling on the 
base ofan ala; h, carina; i,style; k, superior free stamen; 7,stigma; m, anthers; 7, point of union between 
ale and carina; o, point of flexure of the carina; p, part of the upper border of ala, bent outward; gq 
downward extension of the vexillum; r, staminal tube; s, style; ¢, ovary. (After Muller in part.) 
of the ovary. The filaments which compose the staminal tube sepa- 
rate in the hollow of the carma. Each filament bears a fertile anther. 
The pistil is inclosed within the staminal tube, the upper part of the 
style and stigma of which are inclosed with the anthers in the carina. 
The stigma is situated slightly above the stamens in most flowers, 
although in some the anther of the longest stamen is as high as the 
stigma. 
When a bee inserts its proboscis into the staminal tube, it is inserted 
between the vexillum and the carina. In doing this the carina and 
