. Carnegie Institution of Washington publication. THE PLAINS ASSOCIATION. 59. Fig. 18.—Ratihida columnaris. penetrated several feet further. In color the root is reddish brown and covered with a scaly, shreddy cortex, the older parts being quite woody (plate 19, c). Ratibida columnaris.—This species is widely distributed throughout the grassland formation, where it forms summer societies dominating large areas. It has a strong tap-root, 8 to 10 mm. in diameter. For the first 5 inches it tapers very rapidly until at the end of that distance it is not more than 3 mm. in diameter. From that point
. Carnegie Institution of Washington publication. THE PLAINS ASSOCIATION. 59. Fig. 18.—Ratihida columnaris. penetrated several feet further. In color the root is reddish brown and covered with a scaly, shreddy cortex, the older parts being quite woody (plate 19, c). Ratibida columnaris.—This species is widely distributed throughout the grassland formation, where it forms summer societies dominating large areas. It has a strong tap-root, 8 to 10 mm. in diameter. For the first 5 inches it tapers very rapidly until at the end of that distance it is not more than 3 mm. in diameter. From that point it passes vertically downward with a zigzag, irregular course, very crooked and crinkled, tapering slightly (at 12 inches being mm. in diameter) to a max- imum depth of 2 feet. The first 4 or 5 inches is marked by an extraordinary number of more or less horizontal branches which vary in diameter from to mm.; these extend out through the surface soil to a distance of 6 to 12 inches and are themselves profusely branched with small hairlike rootlets from to 2 cm. long. The number of these primary horizontal branches is very large; one count showed approximately 13, while another showed about 40. Below 4 or 5 inches the root is seldom branched, what branches there are being hairlike and from 1 to 3 cm. long. Near the end, however, the tap usually branches into two or three small, short rami- fying parts. The root is dark brown in color, rather tough and unyielding. Four plants were examined (fig. 18). Senecio aureus oblanceolatus.—Senecio is a very common and often abun- dant plains species, frequently forming vernal societies in the grassland. The specimens examined were small plants 6 to 10 inches high. The multiple roots are so finely divided as to be almost fibrous. The number originating from the crown varies from 15 or less to 30 or more. Some of these roots take a downward course from the crown, but many of them pass out at a slight angle from the surf
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