256 THE FERTILISATION OF FLOWERS. [parr ur. — 
a place in the question of the origin of species, that its fertilisation 
by insects in the wild state also deserves our special attention. I 
shall recapitulate first the peculiarities of its flower, next the results — 
of Darwin’s experiments, and finally the insect-visitors that I have — 
observed. 
The flowers, which are set in close whorls on a long spike, are 
almost regular, usually hexamerous but sometimes pentamerous, — 
both forms occurring on the same spike ; they have lost something 
of their regularity by standing not quite horizontally but directed 
slightly upwards. Of the five or six petals which are inserted on 
the edge of the cylindrical calyx-tube, 5 to 7 mm. long, the three 
lower (outer) are usually a little longer than the two or three 
Fig. 85.—Lythrum Salicaria, L. 
. —Long-styled flower from above, after removal of one-third of the calyx, corolla, and stamens. — 
2.—Mid-styled flower, ditto. 
3.—S8hort-styled flower, ditto. 
a, long anthers or stigma; the stigma in Fig. 1, the anthers in 2 and 3 are coated with 
green pollen. 
b, mid-sized ditto; the stigma in Fig. 2, the anthers in 1 and 3 are coated with yellow 
pollen. 
ce, short ditto; the stigma in Fig. 8, the anthers in 1 and 2 are coated with yellow pollen. — 
d, honey 
4,—Mid- styled aout. viewed obliquely from above and frou the right side. 
upper ones; the former are 7 to 11 mm. long, the latter 6 to 10 mm. 
When the flower is fully expanded, as, owing to the crowded 
arrangement, it seldom is, the upper petals stand vertically while 
the lower project obliquely forward; and the latter form, therefore, 
a rudimentary platform for insects. The irregularity in position of 
the stamens and pistil is of more importance; they all occupy the 
inferior (outer) part of the tube, so that insects cannot reach the 
base of the flower between them, but only above them ; and their 
ends are bent upwards, so that the ventral surface of the insect 
Ce ee ee ee 
— ee ee 
must come in contact both with anthers and stigma. Honey is — 
secreted by the fleshy base of the flower, and surrounds the short 
