EqUISETUM ARVENSE. CORN HORSE-TAIL. 



EQUISETUM Lin. Gen. PI. CrypTogamia filices. 



Spica fru&ificationibus peltatis, bafi dehifcentibus, multivalvi. 



Raii Syn. Gen. 4. Hekbte capillares et affines. 



EQUISETUM arvenfe fcapo fru&iricante nudo ; fterili frondofo. Lin, Syjl. Vegetab. p. 457. Sp. PI. p. 

 1 5 16. FL Suec. n. 928. 



EQUISETUM caule florigefo nudo, fterili verticillato, radiorum duodecim. Halitr, Hift. n. 1676. 



EQUISETUM arvetgk Scopoli FI. Cam. n. 1253. 



EQUISETUM arvenfe longioribus fetis. Bauh. Pin. 16. Parkins. 1202. Raii Hift. p. 130. Corn 

 Horfe-taiL 



EQUISETUM fegetale» Ger. emac iit^, 



HIPPURIS minor cum flore. Dod. Pempt. p. 73, 



EQUISETUM minus terreftre. L B. III. 730, Hudfon. FI. Angl ed. 2, p. 265. Lightfoot FI. Scot. 

 p. 647. 



RADIX perennis, gracilis, nigra, articulata, infigniter | ROOT perennial, {lender, black, jointed, exceedingly 

 reptans, fibris nigricantibus e geniculis exortis | creeping, with tufts of black fibres fpringing 



capillata» from the joints. 



SCAPI feminiferi ante caules frondofos prodeuntes, et I STALKS producing the feeds fpringing up before the 

 cito marcefcentes, craffitie culmi triticei ma- 1 leaf-ftalks, and foon withering, the thicknefs 



joris, palmares aut dodrantales, erecti, nudi, | of a large wheat-ftraw, a hand's-breadth or 



lutefcentes, geniculati, geniculis 2. 3. 5. vagi- ¥ more in height, upright, naked, yellowiih, 



nis multifidis, nervofis, membranaceis, cir- 1 jointed ; joints from two to five, covered with 



cumveftiti. y membranous, ribbed fheaths, divided at top into 



I numerous fegments or teeth. 



SPICiE feminiferae terminales, oblongs, obtufe, un- 1 SEED-SPIKES terminal, oblong, obtufe, about an inch 

 ciales. \ in length. 



CAPSULE feu thecse feminiferae plurimae, angulatee, f CAPSULES, or feed-cafes, numerous, angular, upright, 

 erectae, circa receptaculum proprium collocatae, ¥ placed together round a partial receptacle, and 



et fcuto orbiculato lutefcente te&ae, fig. I. de- | covered with a yellowiih orbicular fhield, Jig. 1. 



mum introrfum dehifcentes et pulverem viref- •% finally opening inwardly, and throwing out a 



centem effundentes, Jig. 2. 3. z\l&.jig. 4. | greenifh powder, Jig. 2. 3. magnified, fig. 4. 



CAULIS pedalis et ultra, in apricis obliquus, frriatus, f STALK a foot or more in height, in open fituations 

 fcabrinfculus, geniculatus. Vagina numerofae, % oblique, fbiated, roughifh, jointed. The Sheaths 



denticulate. | numerous and toothed. 



FOLIA verticillata, ocfo circiter in fingulo verticillo, $. LEAVES whirled, about eight in each whirl, fimple, 

 fimplices, cauli limplices. ? and like the ftalk. 



Experiment and obfervation, which have difcovered perfect feeds, if not real Stamina and Piftilla, in fome of the 

 plants of this hidden clafs, have hitherto failed in afcertaining what the powder is, which is contained in fuch 

 abundance in the fpikes of the Horfe-tail, different Botanifls differing widely in their opinions concerning it. 

 Linnjeus and Scopoli confider it as the true feed of the plint: Haller and Adanson as the male duff; and fo 

 ftrongly was the laft mentioned author of this opinion, that he removed it from the cryptogamous plants, and 

 placed it with the family of the pines, from which, however, as Scopoli very judicioufly obferves, it differs toto 

 ccclo. 



We fat down to examine the fructification of this plant, in full expectation of finding Pollen not Seed contained 

 in its cells. We conceived, a priori, that a fubflance fo delicately formed, and fo rapid in its growth, could fcarcely 

 produce capfules with ripe feeds ; but we rofe from our examination in the full belief of the powders being the 

 real feed, fo far as we could judge from its ftructure and ceconomy : a&ual vegetation mufi however be proved, 

 before we can arrive at certainty in this matter. 



If a little of the powder be ihaken out of the fpike on a piece of white paper, a moderate magnifier difcovers a 

 motion in it, efpecially if it be breathed on. A fimilar motion is obferved in the capfules of the Ferns when they 

 throw out their feeds ; and in the fine powder contained in the heads of the Jungermannia, if we apply a very 

 confiderable magnifier to this powder, we find its motion arife from a very different principle from that which 

 actuated the two former. Here every particle of the powder has three or four, very rarely five, fine, pellucid 

 threads, which are club-fhaped at the extremity. Thefe threads are elaftic, and, byvarioufly extending and curling 

 themfelves up, occafion the motion which is fo perceptible. Monf. Adanson, who has minutely defcribed this 

 feed as pollen, compares the appearance it fometimes aflumes to a fpider with its legs ftretched out. Although thefe 

 motions, which are extremely lingular and diverting, are plainly feen with a good magnifier, we never could 

 difcover the body of the feed to make any fort of explofion as Pollen would, under fimilar circumftances of expofure. 



The proper time to examine this curious phenomenon is in April, when the plant produces its fpikes. 



The 'medicinal virtues of the Equifetum are too problematical to deferve notice. Writers on the Materia Medica 

 rank it with the aftringents. 



The Farmer is deeply interefled in a knowledge of this plant, as it is not only one of the moft troublefome and 

 difficult weeds to extirpate that we are acquainted with, but noxious even to cattle, efpecially kine. Haller 

 relates a particular cafe in which it proved fatal to a young heifer, by 'bringing on an incurable Diarrhea. 



Many parts of Batterjea Fields exhibit this plant in perfection. It fometimes is found in meadows and under 

 -hedges ; and, according to its fituatiou, like all other plants, affumes a variety of appearances. 



