78 PROCEEDINGS OF THE AMERICAN ACADEMY. 
lous above, 14 to 4} em. long, 1} to 3 mm. wide, with 4 or 6 irregular 
rows of conspicuous glands beneath, and 4 to 10 pairs of basal sete: 
heads scattered or subcorymbose toward the tips of the upper branches; 
the slender peduncles } to 2 cm. long, generally with 2 approximate sub- 
median bracts and often a third one above: involucre 5-bracteate, 5 mm. 
high, 10-12-flowered ; the purplish bracts linear, acuminate, glabrous : 
rays small, yellowish: pappus 10-25 (sometimes reduced even to 3 or 4) 
upwardly scabrous unequal rufescent bristles slightly or not at all dilated 
below, the longest about 4 mm. long: akenes compressed, 2 to 2} mm. 
long, setulose with rufescent hairs. — Nov. Gen. et Spec. iv. 262, t. 392; 
DC. Prodr. v. 99; Baker in Mart. Fl. Bras. vi. pt. 3, 288; Hieronymus 
in Engler, Bot. Jahrb. xix. 60. P. stricta, Willd. in Less. Linnea, vi. 
710, in syn. Lorentea polycephala, Gardn. in Hook. Lond. Journ. Bot. 
v. 240 fide Baker 1. c. — A common South American species extending 
north to Guatemala. GuaremaLa, Chupadero, Depart. Santa Rosa 
(Heyde & Lux in Exsic. J. D. Smith, no. 3806); Panama (Seemann). 
Both these specimens have the pappus-bristles greatly reduced in number, 
but otherwise they seem identical with the true South American plant 
as figured with the original description. A specimen from Nicaragua 
(Chas. Wright) which Dr. Gray thought might be a form of P. Ber- 
landieri, is too old for determination, but it may belong here. 
Var. Schottii. Much more slender with very slender diffuse 
branches and small leaves: heads scattered and solitary in the axils, on 
eapillary 3—4-bracteate peduncles 2 or 3 em. long: involucre pale, 4 mm. 
high: pappus hardly equalling the akene. — Yucatan, Maxcanu (Schott, 
1865, no. 666). Type in Herbarium of Field Columbian Museum. 
+ + Perennial, stems suberect branching from-near the base. 
vg P. diffusa, Hook. & Arn. A decimeter or so high, with a few sub- 
erect branches rising from the slightly suffruticose base, these branches 
simple or with short densely leafy branchlets above ; stems angulate oF 
subterete, smooth or puberulent, densely clothed with ascending leaves+ 
leaves linear, thick, submucronate, with prominent midribs, smooth or ; 
scabrous on both surfaces, the larger 3 or 4 em. long, 2} or 3 mm. wide, 
with or without 2 or 4 irregular rows of dots beneath, and with 5 to 10 
pairs of sete below the middle (sete reduced or sometimes wanting on 
the upper leaves) : peduncles capillary, from the upper axils, 1 to4¢m. 
long, with 2 to 6 scattered subulate-ovate bracts: involucre 4 to 6 mm. . 
high, of 5 oblong acutish or obtuse bracts, 10-12-flowered: rays linear- 
a hse yellow, 6 or 7 mm. long: pappus of 10 to 20 (rarely only 4 or 5) < 
