Another variety, however, is often sold, which is
striped and blotched with dark purple; and this is probably of crossed
origin, for I found, as well as Mr. Masters, that it did not transmit
its characters at all truly.
From the evidence now given, we may conclude that the varieties of the
sweet-pea rarely or never intercross in this country; and this is a
highly remarkable fact, considering, firstly, the general structure of
the flowers; secondly, the large quantity of pollen produced, far more
than is requisite for self-fertilisation; and thirdly, the occasional
visit of insects. That insects should sometimes fail to cross-fertilise
the flowers is intelligible, for I have thrice seen humble-bees of two
kinds, as well as hive-bees, sucking the nectar, and they did not
depress the keel-petals so as to expose the anthers and stigma; they
were therefore quite inefficient for fertilising the flowers. One of
these bees, namely, Bombus lapidarius, stood on one side at the base of
the standard and inserted its proboscis beneath the single separate
stamen, as I afterwards ascertained by opening the flower and finding
this stamen prised up. Bees are forced to act in this manner from the
slit in the staminal tube being closely covered by the broad membranous
margin of the single stamen, and from the tube not being perforated by
nectar-passages. On the other hand, in the three British species of
Lathyrus which I have examined, and in the allied genus Vicia, two
nectar-passages are present.
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