THE FLORA OF NEBBASKA. If* 



4. CYLIXDROSPERMITM Kuetz. Phyc. Gener. 211. 1843 



Heterocysts terminal, cylindrical; spores originating in oella aexl to the Qel 



erocysts. 

 Etymology: Greek iwXivdpos, cylinder, and anep/ia, seed. 



Cylindrosperninm limiiioola Kuetz. 1. c. 212. 



Cylindrospermum minutum Wood. Prodrom. 120. 1809. 



Filaments slightly curved, pale aeruginous, 3 1 ft in diam., forming a thin, 

 green, membranaceous stratum; cells cylindrical to almost elliptical, 

 slightly contracted at the joints, granular; hetorocyst usually globose, 

 straw colored, 5 n in diam.; spores elliptical-oblong, 10x20 /x. 

 Forms light green, slimy strata on pots in greenhouses; found occasionally 

 also among other algae. The spores and heterocyst easily break off, and 

 the remaining filament is not easily distinguished from an < )s<-illaria. I'l. 

 I., Fig. 11. 

 Cylindrospermum floxnosnm (Ag.) Rabh. Fl. Eur. A_lg. II, 188. 1865. 

 Oscillaria flexuusa Ag. Syst. 06. 1824. 



Stratum gelatinous, aeruginous, indefinite; filaments equal, fiexuous, circin- 

 ate, fasciculcate, or sometimes nearly straight; articulations oblong, OOD 

 stricted at the joints; heterocysts sub-globose; spores oblong-cylindrical, 

 2-5 times longer than broad, distinctly granular, 10 n long; vegetative cells 

 about 4 fi in diam. 

 In a small creek near Lincoln. Not common. 



Family.-OSCILLARIACEAE. 



Filaments simple, with or without a sheath, single or forming extended strata, 

 without heterocysts and without spores; propagation taking place by means of hor- 

 mogones or parts of filaments escaping from the end of the sheath or scattered by 

 dissolution of the sheath, each hormogone consisting of a few cells and quickly develop- 

 ing into a new filament like the one from which it was separated, and by means of gon- 

 idia developed in the cells of the parent plant. 



SYNOPSIS. 



Microcoleus. — Filaments simple or pseudoramose, several enclosed in the same Bheath, 



sheath not lamellose. 

 Schizothrix. — Filaments few in each sheath, sheath firm, lamellose. 

 Oscillaria.— Filaments simple, free, usually sheathloss, oscillating. 

 Lyngbya.— Filaments simple, free, or aggregated into a dense stratum, with a lam. 11-. • 



sheath. 

 Spirulina.-FU.am.ents unicellular, slender, twisted into a close spiral. 

 Phormidium.— Filaments simple, slender, nearly colorless, never oscillating. 

 Arthrospira. — Filaments sheathless, twisted into a lax spiral. 

 Beggiatoa.— Filaments usually indistinctly jointed, colorless, actively oscillating. 



Sub-fam. — Vaginarieao. Filaments two or more in the same sheath. 



1. MICROCOIiEUS. Desm. Cat. PI. Belg. 7. 1823. 



Filaments simple or pseudoramose; sheath hyaline, more or lees regularly 

 cylindrical, scarcely lamellose, in some species . ■ : i - i l y diffluent; apex of 



the filament straight, attenuate; apical cell acute. 

 Etymology: Greek, pmpoc, small, and io f, Bheath, 



