188 NORTH AMERICAN FLORA [V01.UMB 7 



26. GYMNOSPORANGIUM * Hedw. f.; DC. Fl. Fr. 2 : 216. 1805. 



Aecidium Pers. in J. F. Gmel. Syst. Nat. 2: 1472. 1791. 



Roestelia Reb. Prodr. Fl. Neom. 350. 1804. 



Podisoma Link, Ges. Nat. Freunde Berlin Mag. 3 : 9. 1809. 



Aecidium^ Cancellaria Brongn. Diet, Sci. Nat. 33: 521. 1824. 



Centridium Chev. Fl. Env. Paris 1 : 383. 1826. 



Cyglide Chev. Fl. Env. Paris 1 : 384. 1826. 



Hamaspora Korn. Hedwigia 16: 22. 1877, 



Puccinia Kuntze, Rev. Gen. 3^ : 507. 1898, Not Puccinia Willd, 1787, nor Pers. 1794. 



Aecidium is the oldest generic name, and was used in the key on page 129, but as it and 

 Roestelia yiQ.v^ come into general use for form-genera, and their restriction to a true generic appli- 

 cation might sometimes lead to confusion, a later name and one more commonly used is here 

 maintained. 



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, with ostiolar filaments. 



Aecia erumpent, at first cylindrical. 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 imbricate and often articulate, 

 occasionally hygroscopic, becoming curved when wet, the outer walls smooth (except in a 

 few species), rather thin (except in G. hyalinum)^ the inner and side walls smooth, ver- 

 rucose with warty or tubercle-like elevations, rugose with ridges or ridge-like papillae be- 

 ginning 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. Aecio- 

 spores 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, 

 the pores usually 2 in each cell, sometimes 1, 3, or 4, variously arranged, often near the 

 septa, sometimes apical in the upper, rarely near the pedicel in the lower (numerous and 

 scattered in G. multiporwrn) \ pedicels hyaline, elastic, usually of considerable length, 

 cylindrical (carotiform in G, inconspicuum and G. gerfninale) , the walls thick, the outer 

 portions swelling and becoming gelatinized in moisture to form a jelly-like matrix in 

 which the spores appear imbedded. 



Type species, Gymnosporangium conicum Hedw. f. {on Juniperus sp.). 



la present and exclusively considered. 



Heteroecious ; aecia inhabiting family Malaceae (except Nos. 17 and 19). 

 Aecia short, cupulate ; peridium lacerate or erose. 



Aeciospores small (12-23//), the wall thin (1-1.5/^). 1. G. Blasdaleanum. 



Aeciospores large (23-29/"), the wall thick (3-4 /i). 2. G. Sorbi. 



Aecia elongatej tubular at first, in some species becoming altered 

 by dehiscence. 

 Peridium retaining tubular or cornute form, unaltered by 

 dehiscence. 

 Peridium finally dehiscent at apex, slightly or not at all 

 lacerate. 

 Peridial cells verrucose. 



Peridial cells very thick in side view (45-65 /i). 



Side walls of peridial cells verrucose only on inner 



third. 4. G. inconspicuum. 



Side walls of peridial cells verrucose over entire 

 surface. 5. G. Harknessianum- 



Peridial cells moderately thick in side view (16-39 //). 



Aeciospore-wall chestnut-brown. 28. G. Nelsoni. 



Aeciospore-wall pale-yellow. 19. G. gracilens. 



Peridial cells spinulose. 7. G. exiguum. 



Peridial cells rugose. 



Inner and side walls of peridial cells moderately 



rugose; aeciospore-walls dark cinnamon-brown, 8. G. Davisii. 



Inner and side walls of peridial cells coarsely rugose ; 

 aeciospore-walls light chestnut-brown. 16. G. cornutum. 



* By Frank Dunn Kern. 



