u.] THE FERTILISATION OF FLOWERS. 49 
it visited a short-styled flower, would be likely to 
touch against the stigma; or if it first visited a short- 
styled flower, its head would strike against the anthers, 
and, when visiting a long-styled flower, deposit the 
pollen so obtained on the stigma. 
More remarkable, perhaps, in this respect is the 
Purple Loosestrife (Lythrum salicaria), in which three 
forms occur, In the first form the pistil is very long 
and the stigma is far above the anthers, which are in 
two sets—six of them being about two-thirds of the 
length of the pistil, and six about one-third. In the 
second form six stamens are as long as No. 1t’s 
pistil, whilst No, 2’s pistil is two-thirds of that length, 
and the other six stamens are one-third. In the 
third form the pistil corresponds in length with the 
short stamens in the other forms, whilst one set of 
stamens are of the length of No. 2’s pistil, and the 
other set agree with the pistil of No. 1. The long 
stamens produce large pollen grains to fertilise the 
long pistils; the short stamens produce small pollen, 
and the middling-size stamens produce pollen of a 
size half-way between these two extremes, 
Most Umbelliferous plants—such as the Carrot, 
Parsley, Parsnip—have very small flowers, inconspi- 
cuous individually, but from the manner in which 
they are associated in large flat heads, they are 
among the most noticeable objects of the hedgerows. 
They are fertilised chiefly by small insects to whom 
the honey is easily accessible, it being secreted on a 
flat open disc, and therefore it is inaccessible to Lepi- 
doptera and bees with long trunks. At first only the 
anthers are mature, but when they have shed their 
D 
