124 THE FLORA OF NEBRASKA. 



Sometimes resembles N. subglomerata in general appearance, but may be 

 distinguished by its larger antherids and carpogones and by the bluntish 

 or short-pointed leaves. 



Minden. 



PI. XXVI., Fig. 1, 1 a, branches, natural size; Fig. 2, 2 a, parts of leaves show- 

 ing antherids and carpogones. 



Nitella opaca Ag. I.e. 



Plants 10-20 cm. long (5-30 cm., Allen), not greatly branched; verticels of 6-7 

 leaves usually divided into 2-3 terminal one-celled leaflets, abruptly 

 sharp-pointed or bluntish as in N. flexilis, which this species resembles 

 very much in habit; fruiting verticels contracted, though not so much as 

 in N. subglomerata; dioecious, organs of fructification not enveloped in 

 jelly; antherids variable in size, usually large (according to Allen some- 

 times 800 fi in diam.), carpogones 1-3 at a node, crown evanescent, spore 

 300-360x210-300 ft (Migula). 



The dried plants are dark-colored and somewhat opaque. 



In Deadman's Run, Lincoln. 



PL XXVII., Fig. 1, part of a plant natural size; Fig. 2, part of a fruiting ver- 

 ticel x50; Fig. 3, spore x50. 



Xitel la mneroiiata A. Br. Schweiz. Char. 1817. 



Chara mucronata A. Br. Anu. Sc. Nat. Bot. 1, II., 351. 1831. 



Plants about 5-20 cm. long, branching freely, usually 6 leaves in a whorl, 

 primary leaves branched into 2-5 secondary leaflets, these again branched 

 into 1-3 ultimate 2-3 celled segments, end-cell mucroniform; monoecious, 

 fructification not enveloped in jelly, fruit usually in all the divisions of 

 the leaves; carpogones single or aggregated, spore 270-380 /i (Nordstedt), 

 crown persistent. 



This species may be easily distinguished from the other Nebraska species 

 by the repeatedly branched leaves with mucroniform tips. 



Minden. 



PI. XXVIII Fig. 1., part of plant natural size; Fig. 2, fruiting verticel x50; 

 Fig. 3, spore x50. 



Nitella translncens (Pers.) Ag. 1. c, 



Chara translucens Pers. Syn. II., 351. 1807. 



Plants rather large, 10-40 cm. high, not greatly branched; whorls of sterile 

 leaves 5-6, undivided, large, 1-celled, terminated by 4 2-celled, mucronate 

 tips; fertile verticels contracted into small heads, 1-4 mm. in diam.; 

 usually axillary, sometimes terminal, primary leaf 1-3 times divided into 

 4, ultimate leaflets 2-celled, end-cell mucronate, 95-126 /i long, 32-42 fi wide 

 at the base, point thick-walled and sharp; monoecious; carpogones 1-2 

 at a node; spore 230-270 fi long, nearly as wide as long, dark-brown, with 

 5-6 scarcely prominent ridges, membrane of the spore closely reticulated. 



York. The fruiting verticels of this plant are exactly like those described 

 and figured by A. Braun in Nordstedt Fragm. as N. axillrias A. Br. But 

 the spores of N. axillaris are said to be 290-340 fi long. 



PI. XXIX. Fig. 1, plant natural size; Fig. 2, fruiting verticel x50; Fig. 3, spore 

 x50; Fig. 4, membrane x350; Figs. 6 and 7, end-cells of leaves x50. 



Form confervoiues Thuill Flor. Env. Par. 1790. 



Plants very much smaller and more branched than the type; main stems only 

 270 fi in diam.; leaves and leaflets in whorls of 4-5, usually 4; primary seg- 



