62 THE FLORA OF NEBRASKA. 



SYNOPSIS. 



A. Filaments unbrancbed, none of the cells ending in an awn. 



Cells mostly shorter than the diameter Horm iscia 



Cells mostly longer than the diameter Microspore! 



B. Mostly branched, some of the cells either long acuminate or ending in a soft awn. 



Epiphytic, some of the cells furnished with a sheathed awn Aphanochaete 



Epiphytic, awn not sheathed Herposteiron 



Thallus small, forming a determinate globose or lacinlate mass Chaetophora 



Thallus large and indefinite, not penicillate Stigeoclon iv. m 



Thallus large, indefinite, penicillately branched Draparnaudia 



1. HORMISCI A Fries Flor. Scan. 327. 1835. 



Aquatic or rarely aerial; filaments composed of cells in a simple series; chlo- 

 roplasts parietal, laminiform; propagation by four-ciliate macrozoogon- 

 idia, granules and aplanospores; reproduction by the copulation of 

 biciliate microzoogonidia; zygote breaking up into 2-4 or more asexual 

 zoogonidia. 



Etymology: Greek op/iog, chain. 



Horm iscia II acrid si (Kuetz.) Lagerh. in Flora, 1888, p. 62. 

 Ulothrix flaccida Kuetz. Sp. .A.lg. 349. 1849. 



Yellowish green, neither mucilaginous nor shining; filaments fragile; cells 

 6-10 fi, rarely 10 /n, broad, equal to the diameter, or in some varieties three 

 times the diameter; cell membrane hyaline, slender, homogeneous. 

 On damp rocks etc., common. 



Var.— nitens (Menegh.) Hansg. Prod. 61. 1886. 

 Hormidium nitens Menegh. in Kuetz. 1. c. 

 Ulothrix nitens of Wolle's Freshw. Alg. 137. 



Dark green, sometimes forming a membranaceous stratum; cells 6-7^ /j- in 



diam., 8-10 fi long. 

 On damp earth and planks in greenhouse at University. PI. XXII., Fig. 2. 



Hormiscia zonata (Weber & Mohr) Aresch. Act. Soc. Upsal. 1866, p. 12. 

 Conferva zonata Weber & Mohr Reise 97. 1804. 



Yellowish green, mucous, 5-30 cm. long; filaments often contorted or cespitose, 

 aggregated; vegetative cells 12-40, rarely 70, /u broad, equal to 2-3 times 

 shorter than broad; membrane broad, often lamellose; macrozoogonidia 

 12-19x10-13 fi\ microzoogonidia 5-11x4-7^ /i. 

 Streams, Lincoln. PI. XXII., Fig. 4. 



2. MICROSPORA Thuret Ann. Sci. Nat. Bot. 5, XIV., 22. 1850. 



Thallus of articulate, unbranched filaments, without rhizoid attachments; 

 chloroplasts in bands with starch granules; propagation by numerous, 

 very minute, biciliate microzoogonidia formed 1-2 in each cell, or by 

 aplanospores. 



Etymology: Greek fiwpog, small, and o-opa, seed. 



Thuret separated this genus from Conferva on account of the biciliate micro- 

 zoogonidia and the shape of the chloroplasts. 



Mierospora ynlgaris Rabh. Krypt. Flor. v. Sachs. 245. 1863. 



Bright green, articulations more or less swollen, 10 12 /< in diam, 2-3}£ times 

 as long; cell-contents usually very granular, cell-membrane firm. 



