Equisetum pratense Ehrh., Hannover. E. umbrosum J.G.F. Meyer ex Willd., Enum. Internally with prominent carinal and vallecular collenchyma, and chlorenchyma present under the ridges only. Sheath segments slightly grooved.
Teeth deltoid, slightly incurving, with thin white margins.
Commissure long, weakly furrowed, with indistinct anchorcells. Silica pilules clustered near stoma, sparse and obscure on remainder of stomate. Mamillae small, in longitudinal rows. Coniferous stems initially non-green and unbranched, with larger sheaths and longer teeth, becoming green and branched after the spores are shed. Rhizomes dull, black, not rough, with hairs only on sheaths.