330 EQUISETACE.E. Equisetum. 



sheath, eacli tooth representing a leaf. The leaves of the fruiting cone or spike (in 



several close horizontally divergent whorls) are peltate, T) - 7-angled, and bear several 



hood-liko s))orangia on the inner sido. Spores round, furnished with two slender 



tilaments attached by the middle and clavate at the free ends, coiling and uncoiling 



hygroscopically. Protliallus above-ground, green, often variously lobed, usually 



dioecious. 



A genus of about 25 species, some with unbinnclied steins, others with many branches and 

 bianchlets, which aie verticillately arranged just bidow tlie sheathi of the joints. The riiiges of 

 the stem are caUed airincv, tlie furrows vtdlccuhc, and the hollows beneath them are accordingly 

 carinal or vallecular. The surface of the stem bears minute siliceous appendages in the form of 

 granules, tubercles, rosettes, etc. The furrows are provided with sfoniata which have inner 

 guard-cells of soft tissue, and outer siliceous cells marked with radiating lines. — For a full 

 account of the structure see Sach's Text-Book and Jlilde's elaborate lilonographia Equisetonim in 

 Nov. Act Acad. Ca'S. Leop. xxxii, part ii, 1865. 



* Stems of tico hinds; the sterile with many slender spreadlnrj vertkUUde 

 branches ; tlie fertile usuallij unhranched, ^mle, appearing in early sjyring and 

 soon \olthering. 



1. E. arvense, Linn. Sterile stems rather slender, green and herljaceous, 1 to 

 2 feet high, G - I'Jfui lowed ; branches verticillate, very numerous, mostly simple, 

 four-sided, minutely roiighcned, the lowest joint commonly longer than the slutath 

 of the stem ; fertile stems rarely a foot high, light-brown, the loose scarious sheaths 

 mostly distant, whitish, ending in about 12 brown acuminate teeth: spike rarely 

 over an .inch long. — Al. Jhaun, Am. Journ. Sci. xlvi. 83; Mildo, Monogr. 218, 

 t. 1 - 3. E. boreale, Bongard, Veg. Sitch. i 74, fide Milde. 



Sierra Nevada ; head of King's Kiver, 7,000 feet elevation (Bracer) ; Clark's Ranch (Torrry) ; 

 Plumas County, ^frs. It. M. Austin. Common eastward to the Atlantic, and northward to 

 Alaska and Greenland ; also in Europe and northern Asia. There are many variations from the 

 type : sometimes the branches are again regularly branched, and sometimes a fi iiiting stem will 

 remain through tiie summer and develop copious branches like those of the sterile stems. 



2. E. Telmateia, Ehrh. Stems stout, often thick as one's finger; the sterile 

 ones ivory-white or greenish, 2 to G feet high, 20- 40-furrowed, the ridges smooth ; 

 branches verticillate, very numerous, erect-spreading, simi)le, 4-5-sided, the ridges 

 rough and deeply sulcate, the lowest joint shorter than the sheath of the stem ; fertile 

 stems also white, many-furrowed, the loose brownish sheaths very long, ofteji longer 

 than the internodes : spike 1 to 3 inches long. — IMilde, 1. c. 240, t. 4 - G. E. jluvi- 

 atile, Smith. E. eburneam, Schreb. ; Al. Braun, 1. c. 84. 



Near San Fi-ancisco {Hartweg, n. 2038) ; San Luis Obispo (Bracer) ; Santa Barbara (Wood) ; 

 " Redwoods and mountains near Oakland," Bi<ichnc. Oregon and British Columbia, EuroiMj, 

 western Asia, northern Africa, Madeira, etc. Attributed to the shores of the Great American 

 Lakes in various text-books, but probably only through an erroneous label, as pointed out by Dr. 

 Torrey in the Botany of the Mexican Boundary. The verticillately branched stems sometimes 

 produce a fully-develoi)ed terminal spike of fructification, constituting the var. scrotinum of Al. 

 Braun. 



* * Stems all alike, everc/reeii, iinbrannhed, or producing a feio slender cylindri- 

 cal erect branches: fruit produced in summer. Central cavity of the stems 

 very large. 



3. E. robustum, Al. Braun. Stems tall and stout (sometimes as much as 11 

 feet high and nearly an inch thick), 20-48-furrowed ; ridges roughened with a 

 single series of transversely oblong siliceous tubercles : sheaths short, cylindrical, 

 appressed, marked with black girdles at the base, and at the base of the caducous 

 teeth; ridges of the sheaths tricarinate. — Am. Journ. Sci. xlvi. 88; Mihhf, 

 I c. 532, t. 31. 



Not rare, espec ially in the southern half of the State, the whole range of the species extending 

 from British America to Ohio, Louisiana and Mexico, and i)erhaps to New Jersey. Also said to 



