THE FLOWERS OF BRAZIL 



By day the scent of all these flowers is not perceptible, but when 

 the night comes their life begins, and it is surprising to note how 

 the splendid Tiger-orchid, for example, will open its blossoms in 

 as little as three minutes. With slight, jerky movements the petals 

 spring asunder, and a faint pattering sound is plainly audible. 

 Another surprising and fascinating plant is the "Queen of the Night," 

 or "Night-blooming Cereus," a Central American cactus, which 

 opens its great flowers — 8 inches in diameter, white within and 

 yellow without — only for one night, when they exhale a strong 

 scent of vanilla. 



Since the flowers have so subtly adapted their organs of attraction 

 to the insects, it is only to be expected that the process which consti- 

 tutes the aim of all these devices should likewise be regulated in 

 the subtlest and most various fashions. And such is indeed the case. 

 The male reproductive substance, the pollen, is produced in the form 

 of a loosely-held dust of tiny grains, exposed upon anthers supported 

 by flexible stamens. The insect must come into collision with the 

 stamens, and dust itself with pollen, and must then force its way past 

 the stigma, the female organ of conception, so that a few grains of 

 pollen are rubbed off upon the latter. We have seen that the stamens 

 and the stigma, with its pistil and ovaries, commonly ripen at 

 different times, so that the pollen cannot fertilize the stigma of its 

 own flower. But there are plants, like the Mamao-tree, the Ombii, 

 and others, which have separate male and female flowers, the first 

 containing only stamens and the latter only the ovary and its acces- 

 sory parts ; and in most cases these male and female flowers are 

 produced by separate plants, so that there are male trees and 

 female trees. 



Those wonderful flowers, the Orchids, have evolved a quite special 

 mechanism of fertilization. They do not dust one another with their 

 pollen ; for the pollen grains adhere to two little club-shaped anthers 

 or pollinia, which are seated on short stalks or caudicles that spring 

 from a projection above the entrance to the "spur" of the blossom 

 (Fig. 14). The spur is the tubular prolongation at the back of the 

 flower, at the point of which the nectar is secreted. When an insect 

 flies up to the Orchid, it alights on the downward-pointing petal 

 which forms the "underlip" or threshold, and thrusts its proboscis 

 into the spur. In doing so it butts against the projection, and in a 

 moment both pollinia are affixed to its head, like a pair of horns. 



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