86 NATIVE FLOWERS OF VICTORIA. 
spidery petals often being over three inches in length. 
The most common “ spider ” orchid is Caladenia 
dilatata. This is the one with the broad lip (label- 
lum), some of the petals being coloured and brightly 
marked with green. 
The “ greenhoods ” belong to the genus Ptero- 
stylis; they are usually greenish in colour, and the 
upper portion of the flower is shaped like a hood, 
covering the rest of the flower. In many cases the 
labellum or lip is sensitive; if it is touched, or if an 
insect alights upon it, it springs up, and forcing the 
insect into the flower, retains it there for a short 
time, until the lip drops again. Many orchids possess 
this property, and it has been so given to them by 
nature, in order that they may be able to produce 
their seeds, so that the seeds may be fertile — ^that is, 
that they may grow\ It is necessary that the pollen 
must be placed on the stigma. The pollen, by means 
of a growing tube, sends a drop of fertilizing fluid 
down to the young seeds, which gives them the power 
of vitality or life. In orchids, the pollen is not in 
the form of yellow dust, as it is in sunflowers, lilies 
and many other flowers, but it is found in sticky, 
almost solid masses. The insect being forced into the 
flower, almost always receives some of the sticky 
pollen masses on its body, and when it flies to another 
orchid, carrying the pollen with it, the stigma of the 
flow’er coming into contact with the pollen on the 
insect becomes smeared with it and thus fertilization 
takes place. 
One orchid has a very much enlarged lip, which is 
also sensitive. This is a pretty purplish-brown orchid. 
