. An introduction to the structure and reproduction of plants. Plant anatomy; Plants. HAIRS 103 are the source of They are unicellular and may reach a length of 2-5 centimetres and, in the plant's economy, serve for the dispersal of the seeds by the wind. Similar hairs, with the same function, occur on the seeds of the Willow, Willow- herb, and many other The epidermal ceUs of many petals are drawn out into very short processes, or papillce, which are the cause of the velvety surface and prevent wetting. A similar production of papillae is not uncommon on the stomatal surface
. An introduction to the structure and reproduction of plants. Plant anatomy; Plants. HAIRS 103 are the source of They are unicellular and may reach a length of 2-5 centimetres and, in the plant's economy, serve for the dispersal of the seeds by the wind. Similar hairs, with the same function, occur on the seeds of the Willow, Willow- herb, and many other The epidermal ceUs of many petals are drawn out into very short processes, or papillce, which are the cause of the velvety surface and prevent wetting. A similar production of papillae is not uncommon on the stomatal surface of the leaves of tropical plants growing in damp situations [ tropical rain-forest). Branched hairs assume very diverse forms, only a few of which can be mentioned. In the MuUein and Plane they are tree-hke, and consist of an erect multicellular axis from which numerous tapering branches radiate at intervals. More frequent are so-called stellate hairs, in which there is but one set of radiating branches terminating a short stalk which, however, is some- times practically absent [ Deiitzia). Multicellular hairs of this kind are typical of the Lime-family (Tiliacece) and Mallow-family (Malvacere), whilst Fig. 49.—Peltate hair of . ,, , 1-/: J • Sea Buckthorn (Hit- uniceUular ones are exemplihed m , ,, , -^ x ^ pophce rhamnoides). Deidzia (Fig. 48, A). Stellate hairs are also found in the Cruciferfe, but here they are accompanied by simpler forms with onh' two or three branches and by un- branched hairs. A very efficient transpiration-check is afforded by the peltate hairs, which are well seen in the Sea Buckthorn [HippcphcB, Fig. 49), and in Elaagnits, where, owing to the large number of these scale-like structures, the under-surface of the leaf has a characteristic silvery appearance. The short stalk of these hairs is surmounted by a horizontal expansion, consisting of a large 1 The walls of these hairs are practicall}' pure cellulose, ilany hairs, which from their
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectpl, booksubjectplants
