. A textbook of botany for colleges and universities ... Botany. m Fig. 1002. — A diagrammatic longitudinal section of a young xylem strand; c, cambium; y, a young undifferentiated trachea with cross walls as yet un- resorbed; p, a trachea with transversely elongated pits; s, spiral tracheae; a, an annular trachea; m, pith; highly magnified. — From Barnes (Part II).. Fig. 1003. — Tracheids of a gymnosperm with bordered pits; highly magnii&ed.—Alter Chamberlain. are annular or spiral, the wall area largely remains thin (figs. 1002, 1004, 1005). In reticulated vessels, the strengthening fibe
. A textbook of botany for colleges and universities ... Botany. m Fig. 1002. — A diagrammatic longitudinal section of a young xylem strand; c, cambium; y, a young undifferentiated trachea with cross walls as yet un- resorbed; p, a trachea with transversely elongated pits; s, spiral tracheae; a, an annular trachea; m, pith; highly magnified. — From Barnes (Part II).. Fig. 1003. — Tracheids of a gymnosperm with bordered pits; highly magnii&ed.—Alter Chamberlain. are annular or spiral, the wall area largely remains thin (figs. 1002, 1004, 1005). In reticulated vessels, the strengthening fibers form a network, and in the pitted tra- cheids and tracheae, most of the wall becomes thickened, the thin places appearing as small pits (fig. ioo6). Pitted and reticulated vessels usually are larger than those with annular or spiral thickenings. Still another form of thickening is seen in the scalariform vessels, in which transversely elongated pits occur in parallel rows (fig. 1000). Bordered pits occur in many plants, especially in the conifers, where they are arranged in longitudinal rows, a surface view disclosing two concentric rings or el- lipses (fig. 1003); in section there are seen a thickened central portion, the torus, and. 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 Coulter, John Merle, 1851-1928; Barnes, Charles Reid, 1858-1910, joint author; Cowles, Henry Chandler, 1869- joint author. New York, Cincinnati [etc] American book company
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