552 THE EQUISETUM FAMILY. [Equisetum. 



Fruiting stems, in spring, simple, thick, with long loose sheaths, 

 and withering before the barren ones appear. 

 Sheaths of the fruiting stems more than an inch long, with 



numerous subulate teeth 1. E. Telmateia. 



Sheaths under an inch, distant from each other, with about 8 



or 10 lanceolate teeth 2. E. arvense. 



Fruiting stems appearing in or lasting till summer, at the same 



time as the barren ones, and nearly similar to them. 

 Spikes very obtuse. 

 Sheaths with 3 to 5 large teeth. Lower branches recurved and 



again branched 3. E. sylvaticum. 



Sheaths with 14 to 20 long subulate teeth. Branches all un- 

 divided 4. E. pratense. 



Sheaths with 6 to 20 minute teeth. Branches few. 



Stem smooth, not grooved, 10-20 striate. Sheaths cylin- 



dric appressed 5. E. limosum. 



Stem rough, with 10 to 18 grooves. Upper sheaths sub- 



campanulate 6. E. littorale. 



Stem rough, with 5 to 12 grooves. Sheaths cylindric 



appressed 7. E. palustre. 



Spikes acute or apiculate. 



Stem with 8 to 12 grooves. Sheaths cylindric, at length 



black ; teeth slender 9. E. trachyodon. 



Stem with 14 to 20 grooves. Sheaths cylindric, appressed, 



at length black, teeth slender, tips deciduous . 8. E. hyemale. 



Stem very slender, 4- to 10-grooved. Sheaths cylindric, 



teeth short obtuse membranous 10. E. variegatum. 



1. E. Telmateia, Ehrh. (lag. 1268). Great E.—The fruiting stems 

 appear alone early in spring, they are quite simple, 8 or 10 inches high, 

 as thick as a ringer, of a pale-brown colour ; the sheaths rather loose, 

 an inch long or more, completely covering the stem from one joint to 

 the next, of a dark brown, marked with 20 to 30 or more longitudinal 

 striae, and fringed with as many long, subulate teeth, or half as many, 

 these teeth being often joined 2 and 2 together. Spike fully 2 inches 

 long, the lower whorls of scales often distinct. Barren stems appear- 

 ing after the fruiting ones have withered away, often several feet high, 

 white, with the tips of the sheaths black ; the long, crowded, slender 

 branches very numerous in each whorl. E. maximum, Lamk. 



In marshy, shady, wet, or gravelly places, in temperate Europe, not 

 extending northward into Scandinavia, nor perhaps southward into 

 Spain, but eastward to Greece and the Caucasus, and thence all across 

 Kussian Asia, and in North America. Occurs over the greater part of 

 England, Ireland, and western and south-eastern Scotland. Fr. early 

 spring. 



2. E. arvense, Linn. (fig. 1269). Field E. } Common Horsetail. — 

 Fruiting stem simple, thick, 8 or 10 inches high, and dying before the 

 barren ones appear, as in E. Telmateia, but the sheaths are seldom above 

 8 or 9 lines long, at a considerable distance from each other, and have 

 seldom more than about 10 lanceolate teeth, and are dark only in the 

 upper part. Barren stems 1 to 2 feet high, with slender spreading 

 branches, about 10 to 12 in each whorl; these are sometimes slightly 

 branched, but never regularly so as in E. sylvaticum. 



In fields and waste or moist places, throughout Europe and tem- 

 perate Asia, from the Mediterranean to the Arctic regions, and in North 

 America. Abundant in Britain. Fr. spring. 



3. E. sylvaticum, Linn. (fig. 1270). Wood E. — Fruiting stems at 

 first nearly simple, and about a foot high, but soon branched, like the 



