. The natural history of plants, their forms, growth, reproduction, and distribution;. Botany. 848 THE DISPERSION OF SPECIES BY MEANS OF FRUITS AND SEEDS. these circumstances that can supply the propelling force necessary to drive such fruits and seeds as can keep afloat from one shore to another. Special mention must be made of three groups of fruits and seeds belonging to this category. These are, firstly, dry fruits which are rendered buoyant by air-inclosing envelopes, as, for instance, in the case of the marsh-plants known as Sedges {Carex ampullacea, Q. vesicaria, &c.), where the fru
. The natural history of plants, their forms, growth, reproduction, and distribution;. Botany. 848 THE DISPERSION OF SPECIES BY MEANS OF FRUITS AND SEEDS. these circumstances that can supply the propelling force necessary to drive such fruits and seeds as can keep afloat from one shore to another. Special mention must be made of three groups of fruits and seeds belonging to this category. These are, firstly, dry fruits which are rendered buoyant by air-inclosing envelopes, as, for instance, in the case of the marsh-plants known as Sedges {Carex ampullacea, Q. vesicaria, &c.), where the fruit is surrounded by an inflated utricle; secondly, the fruits of Water-Plantains, Flowering-rushes, &c. (Alisma, Bwtomus, Sagittaria, Sparganium, &e.), which are furnished with a thick air-filled cortical parenchyma; and, thirdly, the seeds of some "Water-lilies. In the case of the white Water-liKes. 464.—Dispersion of fruits and seeds by the wind. ^ Anthyllis Vulneraria; two fruiting-calyces are falling from the plant. 2 Longitudinal section through a fruiting calyx belonging to the same plant; the pod is visible in the interior, s Trifolium tomentomTn; one head of inflated fruiting calyces is detached, and another is still attached to the stalk. ^ Longitudinal section through a fruiting calyx belonging to the same. ^ sfedicago scutellata. « Ostrya ca/rpinifolia; branch with two fruit-spikes. ? Longitudinal section through the saccate cupule which envelops the nut in this plant (NymphoBO), each seed is enveloped in a coat (arillus), which loosely clothes the outer integument (testa) of the seed, so as to leave a layer of air between the two. In the species of the genus Nuphar there is no arillus, but the carpels separate when the fruit is ripe into two layers, of which the outer one is green and succulent, whilst the inner one is white and charged with air, and incloses a large number of seeds. In all these cases the seeds are enabled to float by their envelope
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectbotany, bookyear1895
