EQTJISETUM. 415 



outline narrowed upwards. Fertile st. short, with few (4 — 5) 

 sheaths, appearing before the sterile ones. Sterile and fertile st. 

 always distinct. — Damp meadows. P. IV. 



2. E. umbrosum (Willd.) ; sterile st. with about 20 strise very 

 scabrous with prominent points particularly above, branches sim- 

 ple with 3 or 4 simple angles, teeth of sheaths blunt \-ribbed hut 

 not to the tip, fertile st. simple with many crowded deeply toothed 

 sheaths.— S. 2. N. 63. jB. Drummondii Hook., E. B. S. 277/. 

 — Sterile st. 1 — IJ ft. high, nearly naked below; with many 

 whorls of slender branches in the upper part, having 3- or 4- 

 toothed sheaths ; general outline remarkably blunt at the top. 

 Branched fertile st. with larger sheaths and whorls of about 6 

 branches ; simple fertile st. short (4 — 6 in.), with many loose 

 and still larger yellowish-white sheaths with black prominent ribs 

 upwards and 12 — 20 teeth. — Wet places, rare. P. IV. 



3. E. Telmateia (Ehrh.) ; sterile st. nearly smooth with about 

 30 striae and branches, branches rough doubly-angular simple, 

 teeth of sheaths 2-ribbed, fertile st. simple with many crowded 

 large deeply toothed sheaths. — S. 3. N. 67. E.fluviatile Sm., 

 E. B. 2022. — Sterile st. 3 — 6 ft, high ; occasionally bearing a 

 small terminal spike ; furnished from top to bottom with whorls 

 of slender branches which have 4 angles each with a longitudinal 

 furrow, and 4-toothed sheaths. Fertile st. stout, 1 foot or more 

 in height, with many pale brown sheaths with 30 — 40 teeth ; 

 spike large. — Wet places. P. IV. 



** Sterile and fertile stems similar, simple or branched. 



4. E. sylvaticum (L.) ; sterile and fertile st. with about 12 

 furfows and many whorls of slender compound spreading or 

 deflexed branches, sheaths lax ending in 3 or 4 blunt lobes. — 

 E. B. 1874. S. 4. N. 59.— St. 12—18 in. high. Sheaths of 

 the branches with 3 long acute teeth each \-ribhed to its tip. 

 Fertile st. occasionally simple. Spike blunt. General outline 

 of sterile st. pyramidal, of fertile abrupt. — Wet shady places. 

 P. IV. V. 



5. E. limosum (L.); stem nearly smooth with many sUght 

 furrows, teeth of sheaths short rigid acute, branches simple 

 whorled or none. — St. 2 — 4 ft. high. Sheaths rather short. 

 Spike blunt. — a. E. limosum (L.) ; st. smooth, barren st. nar- 

 rowing gradually upwards, branches short rigid slightly tapering 

 upright and equalling the joints of the st. from green sheaths 

 often wanting. — ;8. E.fluviaiile(L.); st. subglabrous, barren st. 

 with a lax whiplike end, branches long slender tapering lax 

 exceeding the joints of the st. from dark brown sheaths rarely 

 wanting.— In stagnant water. P. VI. VII. 



