The growth of the stem is indeterminate, but as each succeeding section is a little smaller than the one below, the time arrives in the history of each when no more can be pushed out and the growth ceases. The undeveloped internodes soon die and thus the stem, if it grows at all, must put its energy into branches, as the silex coating prevents its increase in diameter. 9. _Robustum_ (A. Br.) _E. robustum_ A. Br. Stems 3 to 6 feet tall, 2 to 6 lines wide, 16 to 48 angled, simple or branched the second year; ridges rough with cross-bands of silex; grooves naked with a smooth coat of silex, and when young with a thin white scurfy coat that soon falls off; sheaths tight to the stem, or recurved and deciduous in fragments in age, as broad as long, soon developing a black girdle at base, an ashy or pinkish one through the middle and a black one above, the last usually very small, all variable in breadth and intensity of color; leaves linear, sharply 3 angled; commissural groove not widened above; teeth more or less persistent for a season, seldom torn off by the growth of the stem, articulated to the leaves, cohering, in groups, brown centrally, with tawny margins ½ their height, ending in filiform usually flexuous appendages, the edges beset with unicellular bristles; branches variable in number and length, the sheaths mostly like those of the stem except the teeth always persist and the leaves are usually grooved centrally; spikes usually green, oval, up to an inch long and half as wide, sharply apiculate. _Ramosum_ and _polystachyum_ forms occur in this as well as in _affine_. Rare east of the Mississippi, where it is replaced by var. _affine_. Very common west, where it has been reported from nearly every State. I have seen it from but six localities in the Eastern States, Wallingford, Pa., _T. C. Palmer_; Towson, Md., _C. E. Waters_; Peoria, Ill., _F. E. McDonald_; Illinois, without locality, _Dr. Brendell_; Mattsville, Ind., _Guy Wilson_; Sarnia, Mich., _C. K. Dodge_; accredited to New Jersey by Milde, and also found in the Himalayas. Var. _minus_ Eng. is simply the same thing reduced, often growing with it. As there is already a variety _minus_ of _hiemale_ this name will not stand, and the form is of too little moment to merit another. Stems of this can usually be recognized at a glance, but it is hard to embody the description in words that will enable one to separate it from _affine_ at once. From _Californicum_ it can only be separated by use of a lens, as their appearance is identical.