Chapter XVII. 



THE ORCHID FAMILY. 



This family is the wonder and admiration of all who 

 take an interest in flowers. It attains its finest develop- 

 ment in the tropics, where the common habit is to grow 

 on the trunks and branches of trees, often far from the 

 ground. It is also universal in temperate regions, but 

 there the habit is generally to grow on the ground and 

 produce flowers, which, though too small to attract atten- 

 tion from the gardener, are yet of singular beauty. 



The flowers of Orchids have usually some singular shape 

 that appeals at once to lovers of the curious. But not 

 always so; occasionally they have the same regular form 

 we are familiar with in other groups. The most noticeable 

 feature by which they can be known is that the stamens 

 and style are intimately blended to form a column in the 

 centre or to one side of the flower. Amongst Monocotyis 

 this condition we will only find in this family, but the 

 same arrangement will be found amongst Dicotyls in our 

 common Trigger Plant. 



The ovary is placed below the flower ; it consists of three 

 carpels with a common ovarian chamber, with three lines 

 of minute seeds placed in three lines on the walls. The 

 perianth is normally formed of six parts, but these are 

 often so much changed from simplicity that they are not 

 always apparent. The peculiar structures produced in 

 the perianth are modifications to ensure cross-fertilisation 

 by insects. To assist this the pollen has an interesting 

 feature : instead of being like free dust, it remains in an 

 adherent mass, at one end of which there is a club with 

 a sticky disc. When a fly or bee visits the flower the disc 

 adheres to its back or head ; it then flies away, carrying 

 the pollen mass as a plume hanging over its head. Visit- 

 ing another flower the pollen is rubbed on the stigma and 

 a portion or all of it is left there. 



We have twenty-three genera and about eighty) species, 

 many of which are very common. We will describe some 

 and briefly refer to others. 



One of our commonest genera is Pterostylis, meaning 

 winged style, go named because towards the top of the 

 column there are two delicate wings that converge towards 

 their ends, forming a tube for an insect to travel up 



