Jennings: Manual op Mosses — 11. Ephemeraceae 113 



1. DiSCELIUM Bridel 

 1. DiSCELIUM NUDUM (Dickson) Bridel 



{Discelium mcarnatum (Schwaegrichen) Jennings; D. nudum Bridel; 



Weisia incarnata Schwaegrichen ) 



Plate LXIII 



Characters as for the f.Tnily. 



The Ohio station for this species is near Ashtabula, only a few miles from 

 the northwestern corner of Pennsylvania. 



Allegheny Co.: Four miles east of Monongahela City, C. M. Hepner, April 8 and 

 April 16 (figured), 1934; roadside ditch 1 mile north of Indianola, C. M. Boardman, 

 Nov. 24, 1935, and May 10, 1936. 



Family 11. Ephemeraceae 



Autoieous or dioicous, rarely polyoicous or synoicous; minute, about 1-2 

 mm high, singly disposed or gregarious, mostly stemless; protonema persistent; 

 leaves minute, rosette-like, spreading or erect-spreading; leaf-cells mostly lax, 

 more or less elongate below, rectangular to rhomboid-hexagonal, above shorter, 

 usually smooth; costa none to excurrent, usually present: seta none or short; 

 capsule immersed, sub-globose, c'.eistocarpous (or with dehiscence line in Natio- 

 mitrium); operculum sometimes differentiated but rarely deciduous of itself; 

 spores mostly large and papillore; calyptra mostly small, delicate, mitrate- 

 campanulate. 



Minute plants growing on soil. 



1. Ephemerum Hampe* 



Dioicous, rarely polyoicous: minute plants with abundant and persistent 

 green protonema: upper leaves elongate-lanceolate to linear; costa none or vari- 

 ously developed; leaf-cells lax, mostly thin-walled, rhomboidal: seta rudi- 

 mentary or none; capsule mostly globose and apiculate, cleistocarpous, walls 

 (exothecium) of two layers of cells with stomata; spores large, up to .08 mm 

 in diameter, warty; calyptra campanulate, delicate, torn at the base or some- 

 times only on one side. 



A cosmopolitan genus of about 30 species; most abundant in North Amer- 

 ica, perhaps several of these occurring in our region, but on account of their 

 minute size not yet collected. 



Key to the Species 



A. Costa none B 



A. Costa more or less complete, or vanishing towards the base C 



B. Leaves lanceolate, erect-patent, spores .060-. 080 mm 



1. E. seTTatum [Schreber] Hampe 



* Nanomttnum Lindberg (Micromitrium Austin) differs from Ephemerum m having 

 a rudimentary but not deciduous operculum and the capsule without stomata and with a 

 wall but one cell thick; leaves ecostate and calyptra minute. 



Leaves entire N. synoicum (James) Lindberg 



Leaves serrulate N. Austinii (Sullivant) Lindberg 



