. The ecological relations of roots . ECADS. 115 From the above, as well as from figures 53 and 54, it may readily be seenthat Allionia linearis is a rather stable species as to root system, the root habitdiffering only shghtly in the two habitats. The clusters of small brancheswere quite pronounced in the plains ecad, while this was compensated for inthe sandhill form by a somewhat greater degree of branching. The habit ofsending off one or more large and rather horizontal branches in the surfacefoot of soil was characteristic in both habitats, as was also the strong tap-root, which showed ab
. The ecological relations of roots . ECADS. 115 From the above, as well as from figures 53 and 54, it may readily be seenthat Allionia linearis is a rather stable species as to root system, the root habitdiffering only shghtly in the two habitats. The clusters of small brancheswere quite pronounced in the plains ecad, while this was compensated for inthe sandhill form by a somewhat greater degree of branching. The habit ofsending off one or more large and rather horizontal branches in the surfacefoot of soil was characteristic in both habitats, as was also the strong tap-root, which showed about the same degree of penetration in both Fig. 53.—Allionia linearis from the Fig. 54.—Allionia linearis horn the plains. sandhills. Abronia fragrans.—^This plant is rather widely distributed over the plainsin disturbed areas, where, as in the sandhills, it frequently forms socies. Thelarge, showy, hemispherical clusters of flowers make it very conspicuous. 116 THE ECOLOGICAL RELATIONS OF ROOTS. Three plants were examined. The description for one will answer in generalfor all. The two largest had tap-roots 6 and 7 mm. in diameter respectively;the smaller was only 3 mm. in diameter. Both of the larger plants had 3stems which reached a height of 14 to 16 inches and were either in blossom orin fruit; hence these may be considered typical mature plants. The tap-roots,except where they twist and curve irregularly back and forth for an inch ormore in crevices of the cloddy soil, pursue a vertically downward course. Thesmallest reached a depth of 34 inches, the largest 40 to 43 inches a whole the root is very p
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