THE SCOURING-RUSHES. 



rounded with or without cross-bands of silex. The 

 sheaths are coloured like the stem, or occasionally 

 paler, rarely with a black girdle at base. The leaves 

 of the sheaths usually have a central ridge 

 at base, which fades out as the apex is 

 approached. The teeth are long and slen- 

 der, silvery white in colour, with a narrow 

 streak of dark brpwn down the middle. At 

 maturity these teeth usually fall away, leav- 

 ing the brownish bases, bordered with white, 

 as a narrow brown and white margin to the 

 sheath. 



This species begins to fruit about the 

 first of May, though the catkins may be 

 found as late as midsummer. The late 

 catkins are produced on secondary stems 

 which spring from the base of the earlier 

 ones. The cones are small, ovate 

 or oblong, with the base often en- 

 closed in the uppermost sheath, and 

 the point at apex short or absent. 



The range of the smooth scouring- 

 rush, as usually defined, begins in 

 New Jersey and spreads out in fan 

 shape to the Pacific coast, the line of its south- 

 ern limit passing through Louisiana and Texas, 

 while the line on the north crosses Ohio and 

 Wisconsin, and so on to British Columbia. In 

 the East and South it is extremely rare, and there 

 is a suspicion that the Eastern records are based catkmof 

 on forms that are more properly referred to Equi- scouring- 

 setum hiemale. The form Equisetum hiemale inter- 

 medium closely resembles it, especially in the shape of the 



SHEATH OF 



SMOOTH 



SCOURING- 



RUSH. 



