268 NORTH AMERICAN FLORA [Volume 7 



• 83. Nigredo cucullata (Sydow) Arth. R&ult. Sci. Cougr. 



Bot. Vienne 343. 1906. 



Uromyces cucullatus Sydow, Ann. Myc. 2 : 349. 1904. 



0. Pycnia epiphyllous, crowded in small groups, subepidermal, honey-yellow becom- 

 ing brownish, flattened-globoid, 80-100 m in diameter ; ostiolar filaments about 50 ^ long. 



1. Aecia hypophyllous, crowded in small groups; peridium cylindrical, deeply lacer- 

 ate; peridial cells linear-rhomboidal, 12-15 ju broad by 29-35 ju long, the outer wall 4-6 ju, 

 transversely striate, smooth, the inner wall 3ju, evenly and moderately verrucose ; aecio- 

 spores globoid or oblong-globoid, 19-24 by 22-26 m; wall pale-yellowish, thin, 1 m, closely 

 and prominently verrucose. 



II. Uredinia at first epiphyllous, becoming amphigenous, scattered, small, 0.2-0.3 mm. 



I 



across, roundish, early naked, light cinnamon-brown, pulverulent, ruptured epidermis 

 inconspicuous, urediniospores obovate-globoid, 19-23 by 21-24 ju ; wall pale cinnamon- 

 brown, thin, about 1.5 )Lt, moderately and sharply echinulate, the pores 2, equatorial. 



III. Telia chiefly epiphyllous, scattered or sometimes gregarious and more or less con- 

 fluent, small, 0.3-1 mm. across, roundish, early naked, somewhat pulverulent, blackish- 

 brown, ruptured epidermis inconspicuous ; teliospores globoid, 23-26 by 24-33 /z, often 

 semi-opaque; wall dark chestnut-brown, sparsely and coarsely verrucose, thick, 4-5 ju, the 

 apex much thicker, 9-12 ju, with a broad semi-hyaline umbo; pedicel colorless, firm, 

 slender, 4/x broad, twice the length of spore, or longer. 



On Carduaceae : 



Perymenium. Berlandieri DC, Mexico (state), 



Perymenium discolor Schrad. , Oaxaca. 



Perymenium Mendezii DC, Hidalgo. 



Perymenium. verbesinoides DC, Morelos. 



Zexm,enia aurantiaca Klatt, Costa Rica. 



Zexm.enia sp. , Guerrero. 

 Type locality : Costa Rica, on Zexmenia aurantiaca. 

 Distribution : Central Mexico southward through Central America. 

 ExsiCCATi : Barth. N. Am. Ured. 87, 288, 383. 



31. DICAEOMA S. F. Gray, Nat. Arr. Brit. PI. 1 : 541. 1821. 



Puccinia I,ink, in Willd. Sp. PI. 62 : 67. 1825. Not Pucctnia Willd. 1787, nor Pers. 1794. 



Solenodonta Cast. Cat. PI. Mars. 202. 1845. 



Trichobasis I^v. in Orb. Diet. Hist. Nat. 12 : 785. 1848. 



Ceratitium Rab. Bot. Zeit. 9 : 451. 1851. 



Cutomyces Thuem. Jor. 'Sci. Ivisboa 6 : 239. 1878. 



Rostrupia Lagerh. Jour, de Bot. 3 : 188. 1889. 



Jackya Bubdk, Oesterr. Bot. Zeits. 52 : 42. 1902. 



The genus Dicaeoma is not separable from Nigredo by any important morphological or physio- 

 logical character. As here treated it is distinguished from that genus by the possession of teliospores 

 having more than one cell, and even this distinction sometimes must be arbitrarily interpreted. 

 The genus is retained partly for convenience in systematizing the large number of species and 

 partly to conform with usage. 



Cycle of development includes pycnia, aecia, uredinia, and telia, with distinct alternat- 

 ing phases ; autoecious and heteroecious. Pycnia and other sori subepidermal. 



Pycnia deep-seated, usually globoid or flask-shaped, with ostiolar filaments. 



Aecia erumpent, cupulate, cylindrical, or rarely somewhat indefinite. Peridium rarely 

 wanting, sometimes evanescent, usually firm, colorless, dehiscent by apical rupture, the 

 margins lacerate or erose, erect, spreading, or recurved. Aeciospores catenulate, globoid 

 or ellipsoid, often angular ; wall colorless, verrucose. 



Uredinia erumpent, definite, without peridium, and without paraphyses (except in a 

 few species). Urediniospores borne singly on pedicels, globoid, ellipsoid, or obovoid; wall 

 colored, echinulate or rarely verrucose, the pores two to several (very rarely one), variously 



arranged . 



Telia erumpent or long covered by the epidermis. Teliospores two-celled, or rarely 



with more than two cells; wall colored, firm, smooth, or verrucosely or spinosely sculp- 

 tured, the pores one in each cell, apical or somewhat depressed in the upper cell, in the 

 lower cell somewhere between the septum and the pedicel. 



Type species, Dicaeoma Persicariae S. F. Gray (on Persicaria amphibia). 



