The honey-bee: its nature, homes and productsHarris, William Hetherington
Science
The honey-bee: its nature, homes and products
Harris, William Hetherington
Bee culture; Bees
A condition similar to that described in the cineraria is found in the
nasturtium (_Tropœolum majus_). In the young blossom may be observed
the five stamens fully developed, while the stigma remains quite out
of their reach. Later, when all the pollen is discharged from the
anthers, the pistil throws up its style and stigma, now ready for
fertilisation, which must be effected by the transfer of pollen from
some other blossom of the same or another plant of the species. This
transfer is effected, usually, by the bees.
Another example of this non-coincidence in the times of development of
the stamens and pistil is found in the foxglove (_Digitalis purpurea_),
but the fertilisation is effected by the larger humble-bees. The
two upper and longer stamens shed their pollen before the two
lower and shorter ones. This arrangement partly avoids the risk of
self-fertilisation, while their position, which changes just when the
anthers are ripe, enables them to smear the under side of any entering
bee; while they also shed their pollen abundantly on the thickly-set
hairs lining the mouth of the corolla. A second use is served by these
hairs, viz., that of obstructing the entrance of the smaller kinds of
bees, which could not so effectually fertilise the ovules. The larger
sorts, in their raids upon the nectar, carry pollen from flower to
flower, thus in the best manner bringing about the most desirable
result of cross-breeding.
Passing now to plants in which the pistil develops earlier than the
stamens, we may note the knotted figwort (_Scrophularia nodosa_). On
making a section of a recently opened flower, the style, with its
stigma, may be observed protruding just beyond the lip of the corolla,
while the stamens are hiding away, as it were, in a little pouch
below the entrance of the blossom. When fertilisation by pollen from
another flower has taken place, the pistil droops and withers; while
the anthers grow upwards to the mouth of the corolla, and present their
nectar to the honey-seekers, for conveyance to other flowers of the
species.
[Illustration: Fig. 75.--Section of Scrophularia Nodosa.]
[Illustration: Fig. 76.--Scrophularia Nodosa. (Young bloom.)]
[Illustration: Fig. 77.--Scrophularia Nodosa. (Old bloom.)]
In the common sage (_Salvia officinalis_) we find a very remarkable
contrivance, by means of which the anthers, through a sort of
hinge-like connective, are brought down on the back of a bee entering
the flower. The pollen thus discharged is carried by the insect to
other blossoms, in which the place of the withered stamens has been
occupied by the stigma now ready to receive the grains. Thus again
inter-breeding is secured.
[Illustration: Fig. 78.--Salvia Officinalis. (New bloom.)]
[Illustration: Fig. 79.--Salvia Officinalis. (Old bloom.)]
[Illustration: Fig. 80.--a. Erica Tetralix. b. Anther of Tetralix.]
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