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soon maturing an abundance of green spores, then withering ; sterile 

 stems taller, thinner and with shorter but more numerous inter- 

 nodes; carina? more pronounced, flat, with a row of single or 

 rarely double hooked teeth or bristles on each side ; sheaths shorter, 

 firmer, green to the teeth; the 4-6 lower internodes usually naked, 

 the upper with dense verticils of branches which at first are arched 

 with drooping tips, but gradually straighten as they expand till 

 they are nearly horizontal in shade or even erect in sun. They 

 have 4 or 5 deep grooves and nearly smooth angles, and decrease 

 regularly in size from the base upward, except that the lowest are 

 usually shorter than those next above. Each node produces sev- 

 eral 3-4 angled branchlets, some of which are again branched. 

 The sheaths are green with sharp-pointed spreading teeth. 



The rhizome is rather less than % of an inch in diameter, and 

 is very wide-reaching, at times growing five or six feet in length. 

 It is one of the very few plants that a deep mulch will not kill. 

 When covered to a depth of eight or ten feet with sawdust it will 

 reach the surface in the second year. It is dull, blackish -brown, 

 about 10-angled, sparsely provided with root-hairs and occasion- 

 ally bears tubercles. Usually a cross-section shows a yellowish 

 ring separating the carinal cavities from the valleculas and often 

 each carinal one is enclosed in a still smaller ring derived from 

 this. These thickened rings are present in only a few species and 

 are made much of in diagnosis. 



This is a northern species. It grows from the highest north 

 in Europe to about 71 N. Lat. In America it is reported from 

 Greenland to Cape Nome, Alaska, south to Virginia and Michi- 

 gan. It is very common by borders of rich woods, especially in 

 the cold, wet alluvium bordering streams in the forest region. It 

 is rarely met with in cultivated fields and is reputed to be averse 

 to chalk and lime soils. In its favorite habitat it enjoys most 

 those small bogs where wet, poorly drained arms of a swamp en- 

 croach upon the evergreen forest, where the shade is deep on all 

 sides, but a diffused light filters from above. Here the fine green 

 branches reach out in a veil-like network, each verticil a little 

 smaller than the one below, and the top of the stem curves grace- 

 fully away toward the shade, thus bringing all into fullest relief. 

 In drier situations the stem is less prominently curved, and the 

 branches more ascending, till often in the sun the tips become 

 erect or but slightly divergent. Both forms of the stem start sim- 

 ultaneously in spring, varying in date according to locality, but 



