252 SHADE PLANTS OF THE ALPINE FORESTS 



The flowers are produced quite early in spring, in 

 April or May. They have even been recorded in 

 bloom on Christmas Eve at altitudes of over 5,000 

 feet. 



The flowers bear a curious resemblance to those 

 of a member of the Pea family (Leguminosse), but as 

 a matter of fact, they are constructed quite differently. 

 This will be seen by anyone who takes the trouble to 

 compare a flower of the Kidney Vetch {Anthyllis 

 vulneraria, Linn.), or of the Bird's-foot Trefoil {Lotus 

 corniculatus, Linn.), usually to be obtained not far 

 away, with that of this Polygala. The structure of 

 the typical Leguminous flower will be foimd described 

 in Appendix II. Here the conspicuous organs are 

 formed entirely by the petals, the upper petal being 

 the "standard," the two side petals the "wings," and 

 the two lower petals uniting to form the "keel." The 

 calyx remains small and green. 



In the Box-leaved Polygala, on the other hand, 

 two of the sepals at the sides of the flower are much 

 enlarged, and are bright yellow in colour, spreading 

 or bending outwards to form the wings. Hence in 

 this plant the showy portion of the yellow or rose- 

 coloxired flowers, borne singly or in pairs in the axils 

 of the leaves, is formed partly by the calyx, and 

 partly by the corolla. 



Now we turn to the petals of the Polygala. As 

 a rule, there are only three, two being absent 

 altogether or rudimentary. The lower petal, how- 

 ever, is very large, and is shaped quite like the boat- 



