| 释义 |
phloem Bot.|ˈfləʊɛm|
[a. G. phloëm (C. W. Nägeli Beiträge zur wiss. Bot. (1858) I. 9), f. Gr. ϕλόος = ϕλοιός bark + -ηµα, passive suffix.]
Collective name for the cells, fibres, and vessels forming the softer portion of the fibrovascular tissue, as distinct from the xylem or woody portion; the bast with its associated tissues. Also attrib., as phloem-bundle, phloem-island, phloem-layer, phloem-sheath, phloem-strand, etc.
1875Bennett & Dyer tr. Sachs' Bot. 94 The different forms of tissue of a differentiated fibro-vascular bundle may be classified into two groups, which Nägeli calls the Phloëm- (Bast) and Xylem- (Wood) portion of the bundle... In many bundles the phloëm is formed on one, the xylem on the other side of the procambium. Ibid. 95 These horizontal elements..may be generally designated as rays; within the xylem they are called xylem-rays, within the phloëm, phloëm-rays. 1876Encycl. Brit. IV. 85/2 Found in the bast or phloëm layers of ordinary trees. 1882Vines Sachs' Bot. 440 [In Ferns] A single layer or several layers of cells may often be found at the periphery of the phloëm lying just inside the true bundle-sheath. Russow regards this structure as belonging..to the ground tissue, and he terms it the phloëm-sheath. 1889Phloem-island, -strand [see interxylary adj. s.v. inter- 6]. 1891Ann. Bot. V. 178 The phloëm-islands are produced centrifugally by the cambium. 1914M. Drummond tr. Haberlandt's Physiol. Plant Anat. xiv. 656 The various tissues that are comprised in the general category of secondary phloem are usually arranged in more or less distinct tangential layers. 1951McLean & Ivimey-Cook Textbk. Theoret. Bot. I. xxi. 922 Phloem Islands..are formed by the enclosure of portions of the normal phloem by short arcs of secondary cambium. 1953K. Esau Plant Anat. xii. 265 The phloem is the principal food-conducting tissue of the vascular plants. 1969[see interxylary adj. s.v. inter- 6]. 1975J. D. Haynes Botany xx. 314 The vascular tissue is the transport tissue of the plant, and is composed of two major tissue types, the xylem and the phloem. 1978J. Updike Coup (1979) iii. 95 Some substratum in the phloem or xylem savored smartly of those little glossy red American candies. |