74 PROCEEDINGS OP THE AMERICAN ACADEMY. 



branches: leaves linear, the largest 3 cm. long, acuminate, sometimes 

 mucronate, scabrous, with 2 to 4 pairs of sette toward the bases : heads in 

 an open leafy cyme, or glomerate: involucre 5 mm. high, about 12-flow- 

 ered ; the 5 linear acuminate bracts strongly conduplicate and slightly 

 keeled toward the bases : rays narrow, 2 mm. long : papjius of subequal 

 slender awns, 3^ to 5 mm. long ; in the disk 5 or 6 (rarely 7), in the ray 

 2 or 3 : akenes 2h to 3^ mm. long, minutely short-setose or glabrat.e. ■ — • 

 Prodr. V. 100; Gray, Proc. Am. Acad. xix. 46. — Eastern Mexico, near 

 the coast. Tamaulipas, San Fernando (Berlandier, nos. 1537, 3037), 

 near Tampico (Palmer, 1879, no. 1096) ; Vera Cruz,, between Tanto- 

 yuca and Tampico (Berlandier, no. 732), near I'antoyuca (Berlandier, 

 no. 2152). 



* * * Erect, simple or branching mostly above the base, stems purplish : leaves 

 linear or lanceolate, the glands scattered or in lines between midrib and mar- 

 gins : heads scattered or solitary on long slender peduncles (2 or more times 

 as long as the head) : involncral bracts about 5, acute or acuminate, purplish : 

 rays yellow or purplish. (Forms of P. diffusa may be looked for here.) 

 ■'r-- Awns obviously dilated at the base. 



P. capillaris, DC. Erect smooth or minutely pubescent annuals, 1 

 or 2 dm. high, with slender subtetragonous stems diflfiisely branching above : 

 leaves linear, mucronate, the larger 3 cm. long, 3 mm. wide, above scabridu- 

 lous, beneath with prominent midribs and two rows of large glands about 

 midway between the margins and midribs ; margins with 2 to 5 pairs of 

 setae below the middle : peduncles many, terminal and from the upper 

 axils, capillary, 2 or 3 cm. long, 2-4-bracteate : involucres 4 to 6 mm. high, 

 10-15-flowered: rays oblong, 2 mm. long: pappus 2 to 6 (or even 1) 

 slender awns 4 or 5 mm. long, with or without a few squamellce at the 

 bases : akenes hardly equalling the pappus, appressed short-setose or 

 glabrate. — Prodr. v. 99. P. Jaliscana (printed Taliscana), Hook. «fe 

 Arn. Bot. Beech. Voy. 296 ; Hemsley, Biol. Centr. — Am. Bot. ii. 225, in 

 part; Gray, Proc. Am. Acad. xix. 46; Klatt, Leopoldina, xx. 91 

 (reprint 4). — Southwestern Mexico. Jalisco, Jalisco (Beechy j^rfe 

 Hook. & Arn.), Rio Blanco (Palmer, 1886, no. 760), Plains of Guadala- 

 jara (Pringle, no. 1813, in part) ; Oaxaca, near Las Bacas,^(/e DC. 1. c. 

 There is little doubt that P. Jaliscana, described from incomplete material, 

 is the same as De Candolle's plant. P. Jaliscana was based upon a form 

 with squamelbe at the base of the awns, but in Palmer's Rio Blanco plants 

 akenes with and without squamellre are found on the same individual. 



Var. pancicapitata. Slender, with a few elongated ascending 

 branches : leaves variable in size, the largest 5 cm. long, 5 mm. wide, 



