) On the other hand, in some large masses of Geranium
phaeum which had escaped out of a garden, I observed the unusual fact of
the flowers continuing to secrete an abundance of nectar after all the
petals had fallen off; and the flowers in this state were still visited
by humble-bees. But the bees might have learnt that these flowers with
all their petals lost were still worth visiting, by finding nectar in
those with only one or two lost. The colour alone of the corolla serves
as an approximate guide: thus I watched for some time humble-bees which
were visiting exclusively plants of the white-flowered Spiranthes
autumnalis, growing on short turf at a considerable distance apart; and
these bees often flew within a few inches of several other plants with
white flowers, and then without further examination passed onwards in
search of the Spiranthes. Again, many hive-bees which confined their
visits to the common ling (Calluna vulgaris), repeatedly flew towards
Erica tetralix, evidently attracted by the nearly similar tint of their
flowers, and then instantly passed on in search of the Calluna.
That the colour of the flower is not the sole guide, is clearly shown by
the six cases above given of bees which repeatedly passed in a direct
line from one variety to another of the same species, although they bore
very differently coloured flowers. I observed also bees flying in a
straight line from one clump of a yellow-flowered Oenothera to every
other clump of the same plant in the garden, without turning an inch
from their course to plants of Eschscholtzia and others with yellow
flowers which lay only a foot or two on either side.
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