. An introduction to the structure and reproduction of plants. Plant anatomy; Plants. BORDERED PITS 37 to one side or the other, the torus closes up the aperture of the dome, and thereby any passage of water or of air from one vessel to the other is prevented. Such displacement will occur when the pressure in one vessel differs from that in the adjacent one, so that the bordered pits operate as safety-valves whereby differences of pressure in the wood become locaHsed. The conduction of water in the higher plants is mainly effected by means of vessels, but another kind of conducting F
. An introduction to the structure and reproduction of plants. Plant anatomy; Plants. BORDERED PITS 37 to one side or the other, the torus closes up the aperture of the dome, and thereby any passage of water or of air from one vessel to the other is prevented. Such displacement will occur when the pressure in one vessel differs from that in the adjacent one, so that the bordered pits operate as safety-valves whereby differences of pressure in the wood become locaHsed. The conduction of water in the higher plants is mainly effected by means of vessels, but another kind of conducting Fig. 18.—Tracheids. A, Spiral type, from the leaf of Hog's Mercury Mercurialis). B, Bordered-pitted, from the stem of the Scotch Inr (Pinits). b, border of bordered pit; ;»./., middle lamella ; p, aperture of bordered pit; tr., tracheids. the tracheid, which is likewise dead, is also found in the wood of thicker branches and, more commonly, in leaves. Each tracheid is formed from a single cell which is more or less elongated in form [ prosenchymatous), and usually bears bordered pits (Fig, i8, B) or spiral thickening (Fig. i8. A). The wood of the Fir and other Conifers is entirely made up of long tracheids, similar in appearance to fibres, but bearing pronounced bordered pits (Fig. i8, B). Very narrow bordered pits appearing as oblique slits are not uncommon in fibres 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 Fritsch, Felix Eugene, 1879-; Salisbury, E. J. (Edward James), Sir, b. 1886. London, G. Bell and sons ltd.
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectpl, booksubjectplants
