I have already mentioned its
small corolla, surpassed by the lobes of the calyx and its capacity of
self-fertilization. It has still other curious differentiating
characters; the pollen grains, which are square in _V. tricolor_, are
five-sided in _V. arvensis_. Some transgressive fluctuating variability
may occur in both cases through the admixture of pollen-grains. Even
three-angled pollen grains are seen sometimes. Other marks are observed
in the form of the anthers and the spur.
There seem to be very many local subspecies [45] of the field-pansy.
Jordan has described some from the vicinity of Lyons, and Wittrock
others from the northern parts of Europe. They diverge from their common
prototype in nearly all attributes, the flowers not showing the
essential differentiating characters as in the _V. tricolor_. Some have
their flower-stalks erect, and in others the flowers are held nearly at
right angles to the stem. _V. pallescens_ is a small, almost unbranched
species with small pale flowers. _V. segetalis_ is a stouter species
with two dark blue spots on the tips of the upper petals. _V. agrestis_
is a tall and branched, hairy form. _V. nemausensis_ attains a height of
only 10 cm., has rounded leaves and long flower-stalks. Even the seeds
afford characters which may be made use of in isolating the various
species.
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