24 THE FLORA OF NEBRASKA. 



Family.— SCYTONEMACEAE. 



Filaments branching, not tapering to a hair like point, containing heterocysts of the 

 same width as the other cells. 



1. SCYTOXEMA Ag. Syst. Alg. 40, 1824. 



Filaments single in a sheath, branching produced by deviation of the fila- 

 ment which emerges from the side of the sheath by folding and ruptur- 

 ing it, giving rise to two filaments at right angles to each other; hetero- 

 cysts scattered here and there in the filament without any apparent 

 relation to the branching. 



Etymology: Greek cKmog, skin, and vr/fia, thread. 



Section I. Filaments forming a horizontal stratum. 



Scytoiiema cinereum Menegh. in Kuetz. Spec. Alg. 303. 1849. 



Stratum pulvinate, cinereous, green, occasionally violet or purplish, pale blue 

 when dry; filaments fragile, flexuous, loosely interwoven, sparingly 

 branched, indistinctly articulate, 4-11 ft in diam.; articulations one-half 

 to three-fourths as long as broad; sheath thick, brownish or yellowish, 

 usually incrusted with lime, 8-20 // in diam. 



In flower pots in greenhouse at the University. PL II., Fig. 24. 



Section II. Filaments in erect tufts. (Symphyosiphon Kuetz.) 



JScytoiiema hofiuamii Ag. 1. c. 



Tufts small, ascending, aggregated, dark brown; filaments sparingly branched, 

 erect, olive-green; joints delicately granulose, equal to one-fourth the 

 diameter in length; sheaths close and indistinct above, wider at the base, 

 colorless, yellow; heterocyst intercalated, subglobose, light-yellow, diame- 

 ter of filaments 10-16 /i. 



On damp wood in greenhouses at the University. PL II., Fig. 30. 



Family.— RIVULARI ACE A.E. 



Filaments free or agglutinated into a definite mass, tapering from tbe base to the 

 apex, usually ending in a hyaline hair; heterocysts normally present, scattered or basal. 



SYNOPSIS. 



Gloeotrichia. — Filaments radiate, distinctly sheathed, sheath broad, transversely plicate 

 Isactis — Filaments erect, parallel, attached at base, sheath fibrillose at apex. 



1. GLOKOTRICHIA J. Ag. Alg. Mar. Med. et Adr. 8. 1842. 



Filaments radiate, sometimes pseudoramose sheathed,more or less constricted; 

 sheaths broad, often saccate at the base, transversely plicate, involved in 

 mucus; spores originating in the lower part of the filament. 



Etymology: Greek -ytowg, sticky, and dpi%, hair. 



Gloeotrichia nataiis (Hedw.) Thuret Ann. Sci. Nat. Bot. 6, L, 382. 1875. 

 Tremella natans Hedwig. Theor. Gen., ed II., t. 36 f. 7-10. 1798. 



Globose or angular, tuberculose, variable in size and form, green, becoming 

 brownish; filaments straight, torulose, flexuous, and hyaline above; lower 

 joints more or less compressed; sheath broad, here and there constricted, 

 colorless or yellowish; spores oblong, cylindrical, heterocysts subglobose 

 about 10 n in diam., filament with sheath at base 10-12 [i in diam. 

 Minden. PL III., Fig. 32. 



ttOPERTY LBRARt 

 N. C. State CoUoe* 



