7. _Affine_ (_Eng._) (_E. robustum affine Eng._) _E. hiemale_ of American authors, not L. Stems 18 to 30 inches high, 2 to 5 lines in diameter, finely 16 to 40 angled, dark green, angles with broad bands of silex, rarely with two rows of tubercles. Internodes when dry contracted above and below, widest in the middle as in _hiemale_, scurfy when young; sheaths longer than broad, at first with a black limb, developing a broad ashy band and narrow black basal ring, fading, rupturing and deciduous the second or third year; leaves narrowly linear, sharply 3 angled, the central ridges only rarely centrally grooved except on the branches, where they usually are; commissural groove very narrow, not widened upward; teeth articulated to the sheaths, persistent or usually cohering by their tips and torn off by the growth of the stem, those of each sheath shaped like a candle extinguisher, all telescoped together and borne up on the tip of the stem. Very common in New England and the east generally, where the type of _robustum_ is absent. Toward the west it runs into the next, but it is occasionally found, even to the valley of Mexico (Pringle 3329). Approaches typical _hiemale_ in its long sheaths and size, and differs little except in the cross-bands of silex. Found usually in moist sand near a watercourse; at times on high sandy banks. It is by no means certain that this is the variety described by Engelmann under this name, but from the brief description he gives it seems safe to assume that it is. Two branched forms are found, as follows: a. _Forma ramosum_ f. nov. (f. _Ramigerum_ A. A. E., in Gilbert’s list, p. 26, not A. Br. in Sched., which normally branches at the 3 to 5 middle nodes.) Stems issuing one to several branches from the upper nodes after the death of the top of the main axis; teeth usually persistent and leaves centrally grooved. b. _Forma polystachyum_ Prager. Stems issuing small spiciferous branches late in the season. As remarked by Mr. Gilbert (List, p. 26), these forms are seldom found together and many patches show neither. The stems of this variety persist at least three years and probably longer. I have found but two causes of death, old age not appearing as a factor. Both are fungoid. After the stem has persisted for a time small white patches appear under the epidermis of the upper internode. These increase in number and the internode finally dies, not, however, till the second one shows the disease. This may continue till the whole stem succumbs. The other fungus is a smut that breaks out in small pustules, finally opening in black patches the size of the head of a pin or smaller. They are usually numerous and the stem dies rapidly.