Equisetum variegatum var. anceps Milde, Ann. Mus. Lugd. Bat. 1:71. 1863.
This variety is intermediate in aspect between the species and H. scirpoides and approaches the latter in habit. The stems are evergreen 30 cm. or less in height by 1 mm. or less in diameter and are massed in a mat-like growth. The centrum is from obsolete to one sixth the diameter of the stem and does not exceed the vallecular cavity; the anatomy is variable. The ridges and leaves are 4-8, the teeth persistent,,and the awns deciduous. The branches have the same number of ridges and leaves as the stems or fewer and in some instances they have five leaves while the stem has four; the only instance, so far as I am aware, where a branch has more ridges and leaves than the stem from which it springs. It grows on grassy borders of marl under willow thickets associated with moss and sedges. Parkedale Farm, Mich;, Farwell 2921, July 28, 1912.