- 5 8- 



I E. ARYENSE L. 



Stems dimorphous ; sterile, somewhat rough, with 6-20 con- 

 vex ridges, sheaths slightly campanulate, leaflets convex, grooved 

 on the back, separated from each other by a narrow commisural 

 groove ; teeth herbaceous, lanceolate, acuminate, bordered with a 

 narrow hyaline membrane which often joins two or three together; 

 branches solid, in thick verticils, with 3-4 prominently winged 

 angles. Central cavity |— \ total diameter of stem. Fertile 

 stems evanescent, 3-10 inches high, stout, of 2-8 internodes, the 

 first of which are shorter than the sheaths, gradually increasing 

 in length towards the top, flesh-colored, smooth, slightly angled, 

 tissue filled with water, central cavity f-| total diameter; 

 sheaths increasing in size toward the summit of the stem, brown 

 above, inflated, with deep grooves and rounded angles, teeth 

 large, lanceolate, pointed, grooved; peduncle usually elongated, 

 with a distinct ring (rudimentary sheath) below spike ; spike ovoid 

 or lanceolate about 1 inch long, composed of 10-12 verticils, each 

 containing an average of 9 or 10 clypeoles. Around the world in 

 the northern hemisphere, from 38' to 83 north latitude ; Canaries, 

 Cape of Good Hope; best development between parallels of 

 +o°-45°. 



The stems vary greatly; in height from 3-15 inches, or in 

 Europe, three feet ; in form, from erect to decumbent or prostrate ; 

 in division simple, with erect verticils of branches, or divided 

 into secondary stems which are themselves much branched. The 

 branches start at the nodes just below the sheaths, one to each 

 groove of the stem. In some forms they begin at the base, or 

 are even augmented into secondary stems, especially in case of 

 injury to the main axis; in other forms they branch only above 

 the middle. Usually simple, they occasionally bear secondary 

 branchlets, sometimes even disposed in more or less regular ver- 

 ticils (var. pseudosylvaticum). They are erect, decreasing in 

 length towards the top, as do the internodes, forming a dense 

 brush, especially in the sun in sand; or they are horizontal or re- 

 curved, as sometimes in the shade, or even secund, when the 

 main stem is prostrate. The rhizome spreads horizontally under 

 the earth, at the depth of about a foot. It is about two lines 

 thick, solid, of a dull, dark brown color, slightly angled, thickly 

 covered with cinnamon- colored root hairs, as are the tubercles, 

 which in some forms are abundant. At intervals secondary 

 rhizomes rise to the surface, but the tip of the primary one never 



