156 The Romance of Wild Flowers 
the calyx and the standard have been removed to 
give the upper view of the flower with the entrance 
to the honey on each side of the style. 
The Red Clover appears to be fer- 
tilised almost exclusively by humble-bees 
. in this country, but Hermann Miiller says 
he has often seen the hive-bee in Germany 
forcibly breaking open the flowers for the 
sake of the honey and pollen it could not 
obtain legitimately; and in New Zealand, 
in the absence of humble - bees, the plant 
appears to have adapted itself to self- 
fertilisation. 
Among those native species that are not cultivated 
by the farmer is the Subterranean Trefoil (7. 
subterraneum), a hairy plant, with 
cream-coloured heads containing 
only from one to three perfect 
flowers surrounded by imperfect 
calyces, each of which has five 
rigid lobes. When the flowers 
have become fertilised and the 
pods begin to grow, the flower- 
stalk lengthens until the head 
touches the soil. Then the aborted 
calyces develop into long fibres 
which enter the soil, and the lobes at their tips 
separate and spread out in such manner that the 
pods are pulled down into the ground. The hairs of 
the calyx absorb moisture from the earth and feed 
the ripening seeds—which will not ripen if this 
burying process is prevented. In this species the 
flower falls off as the pods begin to enlarge, but in 
