. The natural history of plants, their forms, growth, reproduction, and distribution;. Botany. DISPERSAL BY WATER. 805 called Pediastrum, which is closely related to the Water-net, and of which one species is shown in figs. 370 ^â ''â¢s. p. 640. The distribution of bud or sprout-like offshoots is seen especially in the Duck- weeds, Alismacese, Potamogetons, Utriculariaceffi, Droseraceee, and Primulacese. Most of the Duckweeds ( Lemna polyrrhiza and L. arrhiza), which float during the summer on the surface of still water, towards the autumn form organs on their flattened stems which become
. The natural history of plants, their forms, growth, reproduction, and distribution;. Botany. DISPERSAL BY WATER. 805 called Pediastrum, which is closely related to the Water-net, and of which one species is shown in figs. 370 ^â ''â¢s. p. 640. The distribution of bud or sprout-like offshoots is seen especially in the Duck- weeds, Alismacese, Potamogetons, Utriculariaceffi, Droseraceee, and Primulacese. Most of the Duckweeds ( Lemna polyrrhiza and L. arrhiza), which float during the summer on the surface of still water, towards the autumn form organs on their flattened stems which become detached from the summer plants, sink to the bottom. Fig. 448.âFrogbit (Hydroeharis Morsus-ranoB). i Winter buds rising to the surface in spring. 2 Young floating plants which have developed from such buds, s Older floating plants. of the lake, and stay there during the winter. Each of these organs is pocket- shaped, and in the hollow the next year's shoot is already laid downâof course, as a minute structure whose semicircular free end scarcely projects above the closely- adjoining edges of the pocket. These detached winter buds sink because their cells, even those of the epidermis, develop large starch gi-ains which are crowded together, and literally fill up the lumens of the cells. There are no air-spaces like those which cause the summer-plants to float on the surface of the water; the stomata as yet are closed, and the whole body, hermetically sealed from the outer world, now has a specific gravity which causes it to sink down to the bottom of the water, where it is protected against the frost. There it remains in a resting condition during the winter. At the beginning of the warmer season the bud wakes from its winter. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Kerner von Marilaun, Anton, 18
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectbotany, bookyear1895
