Billeder på siden
PDF
ePub
[blocks in formation]

this kind are numerous, and indeed in most, if not all plants in which the stamens and pistils meet in the same flower, the application of the pollen to the stigma is completely provided for, independent of foreign aid. But in those species where the stamens only appear in one flower, and only the pistils in another, the pollen must be conveyed to the latter by the winds, or by insects, or in aquatic plants by the waters in which they reside. Most persons, I believe, have read of the very curious contrivance for this end, which occurs in the Vallisneria spiralis. It is diœcious, and the pistilliferous flowers float on the surface attached to a spiral stalk by which they rise or fall according to the height or lowness of the water. The staminiferous flowers are produced under the surface, but when the pollen is ready, they separate from the stalk, rise to the top, and sailing about impelled by the winds or borne by the current, bring the pollen to the pistilliferous flowers, which remain fixed.

As, however, in only a small part of the vegetable world, the stamens and pistils are on different plants, it is obvious that the requisiteness, of insects to convey the pollen is very limited. Now, were the fertilization' of the germen by their means the final object of the nectareous juice, the latter would be wanting in more than nine-tenths of the vegetable kingdom, because in not a tenth part of that

know that almost all plants possess this fluid. We observe also that often, as in the crown-imperial, the sweet juice is produced in great abundance, though the intrusion of insects is totally unnecessary; while in dioecious plants where, in our present point of view, there is most occasion for them, its quantity is by no means remarkable.

We may drop this discussion, and attend to the NECTARY itself. It is commonly, in English, called the Honey-cup, but as it is often any thing but a cup, and as it frequently has nothing to do with honey, the term Nectary is better; and by it we are to understand any organ which may occur in a flower over and above the seven regular parts of fructification, whether we have evidence of such organ forming a sweet fluid or not. "Linnæus usually called every supernumerary part of a flower, Nectary, from analogy alone, though he might not in every case be able to prove that such parts produced honey. This is convenient enough for botanical distinctions, though perhaps not always right in physiology; yet there is nothing for which he has been more severely and contemptuously censured. He was too wise to answer illiberal criticism, or he might have required his adversaries to prove that such parts were not Nectaries. Sometimes possibly he may seem to err, like L'Heretier, in calling abortive stamens by this name. who knows that their filaments do not secrete honey, as well as the tubes of numerous flowers? And

Yet

HONEY-SUCKLE.

CROWN-IMPERIAL.

231

though abortive as to Anthers, the Filament, continuing strong and vigorous, may do its office." *

It being the case then that every supernumerary part of a flower is called the nectary, we may readily conceive its varieties to be very great. It is only indeed by practice and observation that an extensive knowledge of it can be acquired, though it will be necessary at present to point out some of its forms.

On opening the corolla of a honeysuckle you find at the bottom of the tube a quantity of sweet juice, but there is no gland nor extra-organ by which it could have been secreted, and therefore, we must take for granted that it was formed by the tube itself, and such is generally the case in monopetalous flowers. In the crown-imperial (Fritillaria imperialis), there is a deviation from this extreme simplicity. The petals of its corolla are six, and in the claw of each is a pit of a white colour, large enough to hold a grain of hempseed, and full of a transparent sweet fluid. "In the bottom," says Gerard, "of ech of these bels there is placed sixe drops of most cleere shining sweete water, in taste like sugar, resembling in shew faire orient pearles; the which drops if you take away, there doe immediately appeere the like, as well in bignes as also in sweeteness: notwithstanding if they may be suffered to stande still in the flower according to his owne nature, they will never fall away, no, not

if you strike the plant, untill it be broken."*

In

Fig. 80. (a) shows the nectaries in the base of this flower, the upper parts of the petals having been

[merged small][merged small][graphic][subsumed][merged small]

In Ranunculus the nectary is also a pit or pore in the claw of the petal; but in a considerable number of the species of this genus it is much less simple than that of the crown-imperial, being shut in some by an emarginate scale placed before it (b), and in some surrounded by a cylindrical margin. In Hellebore the nectaries are numerous, ranged in a circle, tubular and bilabiate. Fig. 80. (c, c) Frequently the corolla, as in violet, and larkspur, and

* Herbal, p. 153.

HELLEBORE.

ACONITE.

233

sometimes the calyx, as in nasturtium, is prolonged into a spur (calcar), which is the nectary. (d) And in Aconite the nectaries resemble two horns, each bearing on its point a hollow kind of box. Fig. 80. (g) A flower of the grass of Parnassus (Parnassia palustris) is represented at (e), and one of its nectaries separate at (f).

[graphic]
« ForrigeFortsæt »