. Plant anatomy from the standpoint of the development and functions of the tissues, and handbook of micro-technic. e Vascular Bundles.—It will be rememberedfrom the preceding chapter that the cambium ring is composedof two parts: the fascicular cambium consisting of procambiumcells lying between the phloem and xylem which remain prac-tically unchanged in form and retain their power of division,and the interfascicular cambium which is formed by the tan-gential division of primary medullary ray cells that lie in aline connecting the fascicular cambium of contiguous cambium cells beg
. Plant anatomy from the standpoint of the development and functions of the tissues, and handbook of micro-technic. e Vascular Bundles.—It will be rememberedfrom the preceding chapter that the cambium ring is composedof two parts: the fascicular cambium consisting of procambiumcells lying between the phloem and xylem which remain prac-tically unchanged in form and retain their power of division,and the interfascicular cambium which is formed by the tan-gential division of primary medullary ray cells that lie in aline connecting the fascicular cambium of contiguous cambium cells begin active cell division immediately follow-ing the differentiation of the primary tissues told about in thelast chapter, and by the differentiation of these new cells thefascicular cambium adds tissues to the xylem toward the inside,and to the phloem toward the outside, and the interfascicularcambium makes additions in like manner to the primary medul-lary rays. It is comparing the rate of growth of phloem andxylem that the latter increases much more rapidly than the 46 GROWTH OF VASCULAR BUNDLES 47. FIG. 22.—Diagram showing additions to the primary tissues through the activity ofthe cambium and phellogen or cork cambium. Compare this with Fig. 14. In this diagramstone cells have been omitted. 48 SECONDARY INCREASE IN THICKNESS a former. This is due to the fact that when a cambium cell divides,by the formation of a tangential wall, which it usually does,the daughter cell facing the xylem much more frequently differ-entiates into the permanent condition than the one facing thephloem, the latter continuing as a cambium cell; but sometimesthe daughter cell facing the phloem grows to be one of thephloem elements, while the one facing the xylem remains in thecambium condition. The kinds of tissues which the cambium adds to the xylemvary in different plants. In many Gyirmosperms wood paren-chyma cells are formed,but, except in a singlegenus, neither trachealtubes nor woo
Size: 1384px × 1805px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., boo, bookcentury1900, bookcollection, bookdecade1910, bookyear1910
