Elementary botany . ex-amine the stem of this shoot, and of thebranches, we see that the same kind ofleaves are present and that the markings onthe stem are similar. Since the leaves ofthe horsetail are membranous and not green,the stem is green in color, and this per-forms the function of photosynthesis. Thesegreen shoots live for a great part ofthe season, building up material which iscarried down into the underground stems,where it goes to supply the forming fertileshoots in the fall. On digging up some ofthese plants we see that the undergroundstems are often of great extent, and thatboth
Elementary botany . ex-amine the stem of this shoot, and of thebranches, we see that the same kind ofleaves are present and that the markings onthe stem are similar. Since the leaves ofthe horsetail are membranous and not green,the stem is green in color, and this per-forms the function of photosynthesis. Thesegreen shoots live for a great part ofthe season, building up material which iscarried down into the underground stems,where it goes to supply the forming fertileshoots in the fall. On digging up some ofthese plants we see that the undergroundstems are often of great extent, and thatboth fertile and sterile shoots are attachedto one and the same. 576. The scouring rush, or shave grass.—Another common species of horsetail inthe Northern States grows on wet banks,or in sandy soil which contains moisturealong railroad embankments. It isthe scouring rush (E. hyemale), socalled because it was once used forpolishing purposes. This plant likeall the species of the horsetails has JKJ^gg. °f horseUil (E^. „Fig. 325. HORSE TAILS. 283 underground stems. But unlike the common horsetail, there isbut one kind of aerial shoot, which is green in color and shoots range as high as one meter or more, and are quitestout. The new shoots which come up for the year are un-branched, and bear the fertile spike at the apex. When thespores are ripe the apex of the shoot dies, and the next seasonsmall branches may form from a number of the nodes. 577. Gametophyte of equisetum.—The spores of equisetum have chloro-phyll when they are mature, and they are capable of germinating as soon asmature. The spores are all of the same kind as regards size, just as wefound in the case of the ferns. But they develop prothallia of differentsizes, according to the amount of nutriment which they obtain. Thosewhich obtain but little nutriment are smaller and develop only antheridia,while those which obtain more nutriment become larger, more or lessbranched, and develop archegonia. This c
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