Thus out of the forty-nine genera in the first list,
about thirty-two have flowers which are asymmetrical or present some
remarkable peculiarity; whilst in the second list, including species
which are fully or moderately fertile when insects were excluded, only
about twenty-one out of the forty-nine are asymmetrical or present any
remarkable peculiarity.
MEANS OF CROSS-FERTILISATION.
The most important of all the means by which pollen is carried from the
anthers to the stigma of the same flower, or from flower to flower, are
insects, belonging to the orders of Hymenoptera, Lepidoptera, and
Diptera; and in some parts of the world, birds. (10/1. I will here give
all the cases known to me of birds fertilising flowers. In South Brazil,
humming-birds certainly fertilise the various species of Abutilon, which
are sterile without their aid (Fritz Muller 'Jenaische Zeitschrift f.
Naturwiss.' B. 7 1872 page 24.) Long-beaked humming-birds visit the
flowers of Brugmansia, whilst some of the short-beaked species often
penetrate its large corolla in order to obtain the nectar in an
illegitimate manner, in the same manner as do bees in all parts of the
world. It appears, indeed, that the beaks of humming-birds are specially
adapted to the various kinds of flowers which they visit: on the
Cordillera they suck the Salviae, and lacerate the flowers of the
Tacsoniae; in Nicaragua, Mr.
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