| 释义 |
polyarch, a. Bot.|ˈpɒlɪɑːk|
[f. Gr. πολυ-, poly- + ἀρχή beginning, origin.]
Proceeding from many points of origin: said of the primary xylem or woody tissue of a stem or root.
1884Bower & Scott De Bary's Phaner. 351 The xylem is according to the particular case diarch or polyarch, and its starting-points..all lie at equal distances from one another. 1914[see hexarch adj. s.v. hexa-]. 1964H. J. Dittmer Phylogeny & Form in Plant Kingdom xxiii. 563 The xylem may be termed diarch when only two points are present, triarch with three, tetrarch with four, or polyarch with many. |