THE ORIGIN OF FLOWERS 



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st' 



gr f 



easily separate into fine dust and are carried away by the wind until 

 they fall, by chance, far from their place of origin, on the stigma of 

 a female blossom. 



By far the greater number of the phanerogams, however, especi- 

 ally all our indigenous * flowers,' are, as a rule, fertilized by means 

 of insects, and it is amazing to see in what diverse ways, often highly 

 specialized, they have adapted themselves to the visits of insects. 

 Thus there are flowers in which the nectar lies open to view, and 

 these can be feasted on by all manner of insects ; there are others in 

 which the nectar is rather more concealed, but still easily found, 

 and reached by insects with short mouth-parts, e.g. large flowers 

 blooming by day and bearing much pollen, like the Magnolias. 

 These have been called 

 beetle-flowers, because they 

 are visited especially by the 

 honey-loving Longicorns. 



Other flowers blooming 

 by day are especially adapted 

 to fertilization by means of 

 bees ; they are always beauti- 

 fully coloured, often blue ; 

 they are fragrant, and contain 

 nectar deep down in the 

 flower, where it can only be 

 reached by the comparatively 

 long proboscis of the bee. 

 Different arrangements in the 

 different flowers secure that 

 the bee cannot enjoy the 

 nectar without at the same 

 time effecting the cross-pollination. Thus the stamens of the meadow 

 sage (Salvia pratensis) are at first hidden within the helmet-shaped 

 upper lip of the flower (Fig. 41, st'), but bear lower down on their stalk 

 a short handle-like process, which turns the pollen-bearing anther 

 downwards (st") as soon as it is pressed back by an intruding insect. 

 The pollen-sacs then strike downwards on the back of the bee, and 

 cover it with pollen. When the bee visits another more mature flower, 

 the long style, which was at first hidden within the helmet, has bent 

 downwards (gr"), and now stands just in front of the entrance to the 

 flower, so that the bee must rub off a part of the pollen covering its 

 back on to the stigma, and fertilization is thus effected. 



There are other flowers which are specially disposed to suit the 



Fig. 41. Flower of Meadow Sage (Scdvia pratensis), 

 after H. Muller. stf, immature anthers concealed 

 in the 'helmet' of the flower, st", mature anther 

 lowered, gr', immature stigma. gr", mature 

 stigma. U, the lower lip of the corolla, the 

 landing-stage for the bee. 



