Elementary botany . Fig. of stem (rhizome) ofPteris aquilina. sc, thick-walledsclerenchyma; a, thin - walledsclerenchyma; par, parenchyma. 362 RELATION TO ENVIRONMENT. apical cell, the root cap being cut off by successive divisions of the outerface, while the primary root tissues are derived from the three Fig. 420. Median longitudinal section of theapex of a root of the barley, Hordeumvulgare. k, calyptrogen; d, dermat-ogen; c, its thickened wall; pr, peri-blem; pi, plerome; en, endodermis;*, intercellular air-space in process offormation; a, cell row destined to fo
Elementary botany . Fig. of stem (rhizome) ofPteris aquilina. sc, thick-walledsclerenchyma; a, thin - walledsclerenchyma; par, parenchyma. 362 RELATION TO ENVIRONMENT. apical cell, the root cap being cut off by successive divisions of the outerface, while the primary root tissues are derived from the three Fig. 420. Median longitudinal section of theapex of a root of the barley, Hordeumvulgare. k, calyptrogen; d, dermat-ogen; c, its thickened wall; pr, peri-blem; pi, plerome; en, endodermis;*, intercellular air-space in process offormation; a, cell row destined to forma vessel; r, exfoliated cells of the rootcap. (After Strasburger.) 421. Cross-section of fibrovasculav bundlein adventitious root of Ranunculus re-pens, w, pericycle; g, four radial platesof xylem; alternating with them aregroups of phloem. This is a radialbundle. (After De Bary.) Function of the root cap.—The root cap serves an important function inprotecting the delicate meristem or cambium at the tip of the root. Thesecells are, of course, very thin-walled, and while there is not so much dangerthat they would be injured from dryness, since the soil is usually moistenough to prevent evaporation, they would be liable to injury from frictionwith the rough particles of soil. No similar cap is developed on the endof the st
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Keywords: ., bookauthoratk, bookcentury1900, bookdecade1900, booksubjectbotany
