26 ILLINOIS BIOLOGIC A L MONOGRA PHS [116 



Key to the species 

 Calyx lobes orbicular or ovate, overlapping, without dorsal prongs (sometimes present in the 

 first species). 

 Calyx lobes orbicular, denticulate; styles longer than the ovary and capsule, intrastylar 



aperture rather small C. erosa (p. 26). 



Calyx lobes ovate, entire, styles shorter than the ovary and capsule. 



Calyx lobes ovate, usually as long as broad, styles widely divergent; stigmas 

 not particularly convoluted. 



Corolla lobes about equalling the corolla tube; styles broadly conical 



C. mitraeformis (p. 26). 



Corolla lobes usually shorter than the corolla tube; styles not so 



broadly conical C. jalapensis (p. 27). 



Calyx lobes broader than long, styles not so widely divergent; stigmas 



rather larger and convoluted C. rugosiceps (p. 27). 



Calyx lobes more elongated, each with a dorsal prong. 



Corolla lobes oblong, obtuse; scales large, about reaching the filaments, bridged at 



about the middle C. ceratophora (p. 28). 



Corolla lobes ovate, acutish; scales much reduced, shorter than the tube, scarcely 

 bridged C. chapalana (p. 28). 



Cuscuta erosa n. sp. 

 [Figures 8 and 61] 



Stems medium. Flowers glabrous, about 3 mm. long, pentamerous, 

 on pedicels as long as or longer than the flowers, closely clustered about 

 the host in cymose panicles, somewhat reddish brown; calyx lobes orbicular, 

 obtuse, denticulate, overlapping, cupped, membranous at the edges, 

 fleshier in the median portion, sometimes with a short dorsal projection, 

 nearly distinct, shorter than or equalling the corolla tube; corolla campanu- 

 late; lobes upright or spreading, about as long as or slightly shorter than 

 the tube, oblong, obtuse, some flowers possessing more or less of a horn-like 

 projection at the end of a thickened vein-like elevation on the dorsal 

 surface of each lobe near the apex; scales broad, fringed, shorter than the 

 tube, bridged at about their middle; stamens shorter than the lobes; 

 anthers oval, about equal to the subulate filaments; styles subulate, longer 

 than the globose ovary. Capsule globose, circumscissile, usually one 

 seeded; styles stouter and more divergent, the withered corolla about the 

 capsule or capping it; seeds about 1.5 mm. long, globose, ovate, compressed, 

 with a short, linear, transverse line or a dot for a hilum. 



Type locality: Sonora, Mexico. Range: Arizona and northern 

 Mexico. 



Specimens examined: Mexico: Sonora; (Palmer in 1869, the type, in the U. S. Nat. 

 Herb, as sheet 49,836). 



United States: Arizona; Santa Rita Mts., south of Tucson (Engelmann in 1880, 

 Thornber 7219, 7220). 



Cuscuta mitraeformis Engelmann 

 [Figures 27, 71, 141 and 154] 

 C. mitraeformis Engelmann in Hemsley, Diag. PI. Nov., p. 54, 1880. 



