. The ecological relations of roots . ally run off in a horizontal direction, sometimes for nearly 3 feet beforeturning downward. The end of the tap-root is either unbranched or branchedbut little, and is often dead. Hard soil seems to be a marked hmiting factorto root growth, and under this condition, especially, the usual very irregularcourse of descent is greatly emphasized. Twenty-four root systems wereexamined. While one plant penetrated to feet, the average depth wasfound to be feet (fig. 6). Wyethia amplexicaulis.—This large, rather coarse plant is at home onmoist hiUsides and e
. The ecological relations of roots . ally run off in a horizontal direction, sometimes for nearly 3 feet beforeturning downward. The end of the tap-root is either unbranched or branchedbut little, and is often dead. Hard soil seems to be a marked hmiting factorto root growth, and under this condition, especially, the usual very irregularcourse of descent is greatly emphasized. Twenty-four root systems wereexamined. While one plant penetrated to feet, the average depth wasfound to be feet (fig. 6). Wyethia amplexicaulis.—This large, rather coarse plant is at home onmoist hiUsides and especially in valleys, where it forms extensive estivalsocieties. It has a fleshy tap-root, which sometimes measures 9 inches incircumference and may reach a depth of 6 feet 5 inches. It usually has severalstrong laterals which come off from 8 inches to 3 feet in depth, and may runout in a somewhat horizontal direction for 3 or 4 feet from the main at a depth of 1 to 3 feet the whole tap breaks up into 2 to 5 nearly equal. THE PRAIRIES OF THE PACIFIC NORTHWEST. 37 parts which pursue a downward course, or later extend out as laterals. Pri-mary laterals are not much branched. The w^hole root from crown to near thetip is covered with scattered small laterals, usually not over 2 mm. in are poorly branched, not often giving off roots of the fourth order. Thetip of the main root hkewise is Httle branched. The roots dry out and shrinkrapidly upon removal from the soil. The 18 plants examined had an averageroot depth of 5 feet (fig. 7). Heuchera glabella.—This saxifrage has a strong tap-root supplied, especiallyin the first foot of soil, with rather numerous but poorly branched reaches depths of about 5 feet (fig. 8). Leptotsenia miiltifida.—Leptotcenia is a subdominant which forms con-spicuous societies in the vernal aspect. It has a large fleshy tap-root, some-times 7 inches in circumference, wiiich may reach a depth of over 5 feet. Thefusif
Size: 1245px × 2007px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, bookidecologicalre, bookyear1919
