162 Rhodora [August 



SciRPUs etuberculatus (Steiul.), n. comb. S. nmritimus, var. 

 ri/litulrlcu.s Torr. Aim. Lye. Nat. Hist. N. Y. iii. 325 (1836). Rhyncho- 

 .yxn-a etuhcrriihifa Steiid Syn. PI. Cyp. 142 (1855). Scirpu.1 lepiolepis 

 C\\ii\Mn. Fl. 520 (18()()). S. Canhi/i Gray in Canby, Proc. Acad. Nat. 

 Sci. Philad. 1804, 18. 8. cyUndricus Britton, Trans. N. Y. Acad. 

 Sci. xi. 79 (1892). 



SciRPUS ROBU.STus Pursh, Fl. 50 (1814) as now understood by the 

 writer is a tall plant of the shores of the Gulf of Mexico and Florida, 

 extending north to Cape Cod. Its green leaves are very long, equalling 

 or overtopping the stout tall (0.7 to 1.2 m. high) culm; those of the 

 involucre 3 or 4, the longest 2.5 to 4 dm. long: its spikelets are very 

 rufescent, ovoid to cylindric, some sessile, others on short rays: the 

 scales are all pubescent and strongly colored with elongate red mark- 

 ings and the awns many times exceed the cleft tips. 



Northward and in alkaline regions of the interior S. robusius gives 

 way to a variable plant with shorter paler leaves, and the scales of the 

 spikelet.s from whitish-brown to castaneous scarcely if at all rufescent, 

 the outermost scales glabrous excej)! at tip, and the awn only twice 

 or thrice exceeding the cleft-tip. This plant of the northern and 

 interior portions of the continent, as stated, is very variable, but a 

 prolonged study supplementary to a former attempt to separate the 

 plants clearly ^ has failed to reveal any constant characters by which 

 the plants can be separated specifically. This series of variations as 

 understood by the writer falls into the following arrangement. 



S. r.\MPE8TRis Britton. Culms 0.3 to 1 m. high, usually exceeding 

 the stiff pale leaves (3 to 9 mm. broad): involucral leaves 2 (or 3), 

 the longer 1 to 2 dm. long: spikelets whitish brown, ovoid to cylindric, 

 1 to 2 cm. long, to 10 mm. thick, 2 to 11 in a dense glomerule occasion- 

 ally a few in a secondary glomerule: scales puberulent, or the outer- 

 most glabrous except at tip; the slightly curved awn twice or thrice 

 exceeding the cleft-tip: achenes lenticular, plano-convex or obscurely 

 trigonous. — Britton in Britton & Brown, 111. Fl. i. 267, fig. 627 (1896); 

 Bicknell, Torreya, i. 95 (1901). S. robi/fifiis\ var. campes-fris Fernald, 

 Rhodora, ii. 241 (1900). — Manitoba to Kansas, Nevada, ea.stern 

 California and northern Mexico. Northward and in the mountains 

 passing to 



Var. paludosus (A. Nelson), n. comb. Similar but with the scales 

 drab to castaneous. S. paludosus A. Nelson, Bull. Torr. Bot. Club, 

 xxvi. 5 (1899); Bicknell, 1. c. 94 (1901). S. robusfus, var. paludosus 

 Fernald, 1. c. (1900). Alkaline soil, from the Gulf of St. Lawrence 



» HHODOR.'i, ii. 238 (1900) 



