Ecological relations of roots (1919) pp. 27-28
John E. Weaver

Rosa arkansana

This shrub is widely distributed throughout the scrub and prairie areas. Although usually held in check in the dense grassland sod, except where local disturbances have favored its development, in the sub-climax grassland it frequently forms dense brush over the less-exposed slopes. In the sandhills westward it again assumes an important role, areas several acres in extent frequently being controlled by this species.

As shown in plate 16, A, this plant propagates by rhizomes. This parent plant had given rise to 5 distinct clumps of stems, the youngest of which was 5 years old and more than 5 feet from the oldest. Fragments of other horizontal parts, which had not yet developed shoots, may be seen. It may also be noticed that the plant next to the parent is the only one that has developed a tap-root of its own. Indeed, the other roots arising from the horizontal portion ran obliquely upward, rather horizontally or, at most, only very obliquely downward, and none reached any considerable depth when compared with the taps from the older plants. The tap-root from the second plant reached a depth of 15 feet 2 inches; the main tap pursued a nearly vertically downward course to a depth of 21 feet 2 inches.

It should be noted here that these roses grew about midway up a southeast slope. Here the loess soil was intermediate between that described for Lygodesmia near the crest and for Amorpha near the foot of the hill. Beyond a depth of 10 feet the soil was quite compact.

Plate 15, B, illustrates well the paucity of large branches. The lateral spread of any branch measured horizontally from the base of the crown did not exceed 4 feet. Although many fine branchlets occurred along the course of these main roots and extended off laterally for distances of 6 to 18 inches, still other portions were quite free from branches. The breaking up of the larger roots near their extremities into numerous long, slender, often more or less parallel rootlets is well shown on the root in the figure, which ends at a depth of about 6 feet.

The older woody roots can easily be identified by scraping off the outer black part of the thin cortex, which then reveals a bright red color, while similar treatment of the younger roots shows their orange color.

15B Rosa arkansana, the roots shown in two sections. 16A Rosa arkansana, showing method of propagation.
Prairie plants and their environment (1968) p. 59