. The ecological relations of roots . e repeated branching. They werebranched repeatedly from their origin at the base of the plant to theirextremity with both large and small branches, which ramified in all directionsand thus furnished an enormous absorbing surface. The ultimate root end-ings, whether of the shorter or larger branches, consisted of much-branchedand very delicate brushlike termini, to which the soil clung with great smaller branches, except for their lesser extent, are sinailar to those alreadydescribed. The deep anchorage and absorbing system of this plant consis
. The ecological relations of roots . e repeated branching. They werebranched repeatedly from their origin at the base of the plant to theirextremity with both large and small branches, which ramified in all directionsand thus furnished an enormous absorbing surface. The ultimate root end-ings, whether of the shorter or larger branches, consisted of much-branchedand very delicate brushlike termini, to which the soil clung with great smaller branches, except for their lesser extent, are sinailar to those alreadydescribed. The deep anchorage and absorbing system of this plant consisted of 4 mainroots, which at the outset were to 3 mm. in diameter. These extended 62 THE ECOLOGICAL RELATIONS OF ROOTS. almost vertically downward, following a more or less irregular course throughthe hard soil, branching as shown in figure 21 and reaching a maximum depthof 35 inches. While the shallower roots were brownish in color and very-tough, these deeper roots were glistening white and much more fragile (, 1900).. Fig. 21.—Opuntia camanchica. Fig. 22.—Top view of surface roots of Opuntia caman-showing vertical anchorage chica, showing the wide lateral spread, roots. Opuntia fragilis.—^This cactus has a distinctively shallow root system. Onall sides roots extended out from the base of the plant, ranging from 1 to 2 diameter, some having a lateral spread of 16 inches. There were about 20on the plant examined. Most of these took a course parallel with thesurface of the soil and lay within 3 inches of the surface, but a few took a THE PLAINS ASSOCIATION. 63 slightly more downward course, penetrating to a depth of not more than 8inches. The first 3 or 4 inches of the root were sparingly branched, the fewbranches being mostly mere tufts of rootlets not more than 3 or 4 mm. inlength. Throughout the rest of their course these divergent roots wereabundantly supplied with a system of laterals to mm. in diameter and1 to 12 cm. long. These laterals
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Keywords: ., bookcentury1900, bookdecade1910, bookidecologicalre, bookyear1919
