EQUISETUM. 261 



above these the oblong -ovate blunt cone is seated on a 

 bare stalk-like portion of the stem, one to two inches long. 

 The stems are round, succulent, pale-coloured, with about 

 twelve slender ridges and corresponding shallow furrows, 

 nearly smooth, the siliceous particles which coat the sur- 

 face being too minute to impart much roughness. The 

 sheaths are large and loose, and are divided at the margin 

 into three or four bluntish lobes ; their lower half or 

 tubular portion is pale-green, their upper half or lobes 

 bright-russet ; they have an equal number of ribs with the 

 stem. The slender branches, which are deflexed, grow to 

 about a couple of inches in length, and produce from their 

 joints a series of secondary branches, which grow from 

 about half an inch to an inch in length. The averao-e 

 height of the fertile stems is about one foot. 



The barren stems are more slender and less succulent 

 than the others : they also produce more numerous whorls 

 of branches. These grow from fifteen to eighteen inches 

 high, and are ribbed like the others, only somewhat more 

 prominently. The sheaths fit closer than those of the 

 fertile stems, but in colour and in the division of their 

 margin they resemble them exactly. The whorls of 

 branches arc very dense, being compoundly branched. 



