See also:sole genus of the botanical natural
See also:order Equisetaceae, consisting of a
See also:group of vascular cryptogamous
See also:plants (see PTERIDOPHYTA) remarkable for the vegetative structure which resembles in general appearance the genera of flowering plants
See also:Casuarina and Ephedra . They are herbaceous plants growing from an underground much- 4fejftt4ap jt . From Strasburger's Lehrbtah der Botanik, by permission of Gustav Fischer . Equisetum arvense . A, Fertile shoot, springing B, C, Sporophyllsbearing sporangia, from the rhizome, which which in C have opened . also bears tubers; the D, Spore showing the two
See also:spiral vegetative shoots have bands of the perinium . not yet unfolded . F, Dry spores showing the ex- F, Sterile vegetative shoot. panded spiral bands . (A, F, reduced . B, C, D, E, enlarged.) branched rootstock from which
See also:spring slender aerial shoots which are
See also:green, ribbed, and bear at each
See also:node a whorl of leaves reduced to a toothed sheath . From the nodes spring whorls of similar but more slender branches . Some shoots are sterile while others are fertile, bearing at the
See also:apex the so-called fructification—a dense
See also:oval, oblong conical or cylindrical spike, consisting of a number of shortly-stalked peltate scales, each of which has attached to its under
See also:surface a circle of spore-cases (sporangia) which open by a
See also:longitudinal slit on their inner side .
The spores differ from those of ferns in their
See also:outer coat (exospore) being split up into four
See also:club-shaped hygroscopic threads (elaters) which are curled when moist, but become straightened when dry . In most
See also:species the fertile and sterile shoots are alike, both being green and
See also:leaf-bearing, but in a few species the fertile are more or less different, e.g. in E. arvense the fertile shoots appear first, in the spring, and are unbranched and not green . Any portion of the underground rhizome when broken off is capable of producing a new plant; hence the difficulty of eradicating them when once established . There are 24 known species of the genus which is universally distributed . The corn
See also:horsetail E. arvense, one of the commonest species, is a troublesome
See also:weed in clayey cornfields (see fig.) . The fructification appears in
See also:March and
See also:April, terminating in
See also:short unbranched stems . It is said to produce diarrhoea in such
See also:cattle as eat it . The bog horsetail, E. palustre, is said to possess similar properties . It grows in marshes, ditches, pools and drains in meadows, and sometimes obstructs the flow of
See also:water with its dense matted roots . The fructification in this species is cylindrical, and in that of E. limosum, which grows in similar situations, it is ovate in outline . The largest
See also:British species, E. maximum, grows in wet sandy declivities by railway embankments or streams, &c., and is remarkable for its beauty, due to the abundance of its elegant branches and the alternately green and
See also:white appearance of the
See also:stem . In this species the fructification is conical or lanceolate, and is found in April on short, stout, unbranched stems which have large loose sheaths .
Horses appear to be fond of this species, and inSweden it is stored for use as winter
See also:fodder . E. hyemale, commonly known as the Dutch rush, is much more abundant in
See also:Holland than in Britain; it is used for polishing purposes . E. variegatum grows on wet sandy ground, and serves by means of its fibrous roots to bind the sand together . The horsetails are remarkable for the large quantity of
See also:silica they contain in the cuticle (hence their value in polishing), which often amounts to
See also:half the
See also:weight of the ash yielded by burning them; the roots contain a quantity of
See also:starch .
HORSERADISH (Ger. Meerrettig ; Fr. raifort = ravine...
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