(4=7) 



the thin-walled spores might represent urediniospores but that view 

 cannot be substantiated. It embodies a confused idea of the essen- 

 tial differences between teliospores and urediniospores. If the thin- 

 walled spores put out long undivided germ-tubes as claimed, this 

 must have been due to unusual conditions of growth, for it is well 

 known that under certain special conditions, particularly when 

 growing entirely submerged, the thicker-walled spores, also behave 



6. Generic Description 

 Order UREDINALES 



Family AECIDIACEAE 



Genus GYMNOSPORANGIUM Hedw. f.; DC. Fl. Fr. 2: 



216. 1805 



Cycle of development includes pycnia, aecia, and telia, with 

 distinct alternating phases; heteroecious and autoecious. Pycnia 

 and other sori subepidermal. 



Pycnia deep-seated, usually globoid, generally prominent and 

 conspicuous, at first honey-yellow, usually becoming blackish, 

 globose or flattened globose, with ostiolar filaments. 



Aecia erumpent, at first cylindric. Peridium dingy white, 

 in a few species short and cupulate but usually elongated into a 

 more or less tubular form, membranous, tending to rupture by 

 longitudinal slits along the sides; peridial cells imbricated and often 

 articulated, occasionally hygroscopic becoming curved when wet, 

 outer walls smooth (except in a few species), rather thin (except 

 in G. hyalinum), inner and side walls smooth, verruculose with 

 low wart-like protuberances, verrucose with warty or tubercle- 

 like elevations, rugose with ridges or ridge-like papillae beginning 

 on the inner wall, directed downward and outward and extending 

 obliquely on to the side walls, or spinulose with diminutive spines 

 or spicules, usually rather thick. Aeciospores globoid to broadly 

 ellipsoid, wall colored, verrucose, usually with numerous, scattered, 

 evident germ-pores. 



Telia erumpent, naked, usually definite, variously shaped, 

 gelatinous and elastic at maturity, expanding considerably when 

 moistened. Teliospores chiefly 2-celled, in some species 3-, 4- or 5- 

 celled, by transverse septa; walls colored, of varying thickness, 

 smooth; pores usually 2 in each cell, sometimes 1, 3 or 4, variously 

 arranged, often near the septa, sometimes apical in the upper, rarely 



