Class XXIV. Order I. 383 



ridges rough with minute teeth, which are hardly visible with- 

 out a glass. The joints of the stem are surrounded with short 

 sheaths, coloured with black and white rings, and toothed at the. 

 top. The fruit grows in an ovate, terminal ament, composed of 

 peltate, six sided scales, bearing the seeds inside. 



The whole surface of the stem is rough, like a file, and is 

 used in scouring and polishing metallic vessels. Its cuticle, ac- 

 cording to Mr. Davy, contains a considerable portion of siliceous 

 earth. Perennial. 



EQUISETUM ULICINOSUM. Muhl. Pipes. 



Stems somewhat branched ; branches from the mid- 

 dle joints, unequal. 



A very tall, slender species, growing in the water at the 

 edges of rivers and ponds. Stems erect, round, furrowed, nearly 

 smooth. Joints invested with smooth sheaths ending in even, 

 acute, black teeth. Both the barren and fertile stems are fur- 

 nished with a few short branches, chiefly from about the middle 

 joints. The lowermost and uppermost of these are generally 

 single or in pairs, the rest in unequal whorls. Ament terminal, 

 oblong-ovate. Banks of rivers &c. Perennial. 



Under the name of pipes, this plant is prized by farmers as a 

 valuable food for cattle, who are extremely fond of it. 



EquisETUJi ARVENSE. -L. Field Horsetail. 



Fertile scape naked ; barren frond with whorled 

 branches, decumbent. L. 



The fruitful stems of this plant appear in April, and soon de- 

 cay. They are erect, smooth, furrowed, and without branches, 

 their joints surrounded with large, swelling sheaths, which end 

 in long, blackish teeth. Spike terminal, oblong-ovate, with a 

 membranous border below it. The barren stems are taller and 

 more durable ; they are erect, or ascending at base, roughish, 

 their joints furnished with sheaths and large whorls of simple 

 ascending branches. These branches are three or four cornered, 

 with sheaths at their joints, ending in the same number of teeth. 

 Moist ground, South Boston. Perennial. 



