At this point there forms a prolongation
of the tissue of the dodder--a sort of cone, which penetrates the stalk
of the host plant. After this, through the increase of the stem and
branches of the parasite, the supporting plant becomes interlaced on
every side, and, if it does not die from the embraces of its enemy, its
existence is notably hazarded. It is possible for a _Cuscuta_ plant to
work destruction over a space two meters in diameter in a lucern or
clover field; so, should a hundred seeds germinate in an acre, it may be
easily seen how disastrous the effects of the scourge would prove.
These enemies of our agriculture were scarcely to be regarded as
injurious not very many years ago, for the reason that their sources of
development were wanting. Lucern and clover are comparatively recent
introductions into France, at least as forage plants. Other cultures are
often sorely tried by the dodder, and what is peculiar is that there are
almost always species that are special to such or such a plant, so that
the botanist usually knows beforehand how to determine the parasite
whose presence is made known to him.
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