Here, again, on the roadside is a bit of plantain. Everybody knows its
flat rosette of green leaves and its tall spike of grass-like blossom,
with long stamens hanging out to catch the breeze. Now plantain is a
case exactly analogous to dog's mercury. It is an example of a degraded
blossom. Once upon a time it was a sort of distant cousin to the
veronica, that pretty sky-blue speedwell which abounds among the
meadows in June and July. But these particular speedwells gave up
devoting themselves to insects and became adapted for fertilisation by
the wind instead. So you must look close at them to see at all that the
flowering spike is made up of a hundred separate little four-rayed
blossoms, whose pale and faded petals are tucked away out of sight flat
against the stem. Yet their shape and arrangement distinctly recall the
beautiful veronica, and leave one in little doubt as to the origin of
the plant. At the same time a curious device has sprung up which
answers just the same purpose as the separation of the male and female
flowers on the dog's mercury. Each plantain blossom has both stamens
and pistils, but the pistils come to maturity first, and are fertilised
by pollen blown to them from some neighbouring spike. Their feathery
plumes are admirably adapted for catching and utilising any stray
golden grain which happens to pass that way. After the pistils have
faded, the stamens ripen, and hang out at the end of long waving
filaments, so as to discharge all their pollen with effect. On each
spike of blossoms the lower flowerets open first; and so, if you pick a
half-blown spike, you will see that all the stamens are ripe below, and
all the pistils above. Were the opposite arrangement to occur, the
pollen would fall from the stamens to the lower flowers of the same
stalk; but as the pistils below have always been fertilised and
withered before the stamens ripen, there is no chance of any such
accident and its consequent evil results. Thus one can see clearly that
the plantain has become wholly adapted to wind-fertilisation, and as a
natural effect has all but lost its bright-coloured corolla.
Public-domain text, read in full here on John Shaqi.
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