6-9 mm. long; inner phyllaries oblong, acute, a little shorter than the outer; 

 rays about 8, whitish to roseate, 5-9 mm. long, cuneate-obovate, apically 2- or 

 3-dentate; disk corollas yellow; achenes subfusiform, linear, 9-16 mm. long; 

 pappus awns 2 to 4, erect, retrorsely barbed, about 2 mm. long. 



Infrequent in wet meadows, seepage areas and along streams and on shores of 

 lakes in the Tex. Trans-Pecos mts., N.M. (widespread) and Ariz. (Apache and 

 Coconino to Cochise, Santa Cruz and Pima cos.), summer-early fall; Tex., Colo., 

 N.M., Ariz., s. and s.e. to Pue. and Michoac. 



36. Marshallia Schreb. Barbara's-buttons 



Perennial erect herbs from caudexes or rhizomes with fibrous roots; leaves 

 alternate, simple, entire, 1- to 3-nerved, glabrous, sessile or contracted into 

 subpetiolar bases, the stem leaves somewhat clasping when present; heads solitary 

 at the end of the stem or branches; involucres hemispherical or campanulate; 

 phyllaries herbaceous, often with hyaline margins, subequal, in 1 or 2 series, 

 imbricated or merely approximate and not at all imbricate; receptacle convex or 

 conical, chaffy throughout; pales herbaceous, often hyaline-margined below, nar- 

 rowly linear in outline, longer than the achenes, semirigid; ray flowers absent; 

 disk flowers perfect, fertile; corollas white, cream-colored, pale-lavender or pur- 

 plish, never yellow, longer than the pales, externally pubescent, the tubes slender, 

 the 5 equal lobes of the limb long and linear-obtuse; achenes turbinate or clavate, 

 truncate, somewhat 5-angled, 10-ribbed, the achene-surface between the ribs 

 concave and usually beset with minute resin-dots, these rarely absent; pappus scales 

 5 (sometimes 6), erect or spreading, forming a crown at the summit of the 

 achene, membranous-scarious, white-hyaline or ferrugineous, ovate to ovate- 

 lanceolate or triangular-lanceolate, sessile, the apexes acuminate or acute, the 

 margins regularly or irregularly serrulate or lacerate. 



About 10 species, in southern United States. 



1. Phyllaries and pales merely acute or obtuse, not subulate-tipped, glabrous; 

 phyllaries not winged; flowering in the spring and early summer.... 

 1. M. caespitosa. 



1. Phyllaries and pales strongly acuminate or subulate-tipped, pubescent; phyl- 

 laries usually winged below the middle; flowering late summer and 

 early fall 2. M. tenuifolia. 



1. Marshallia caespitosa DC. 



Perennial herb (1-) 2-4 (-6) dm. tall with a short rhizome; leaves entire, 

 gradually tapering below the middle into a winged subpetiolar base; lowermost 

 leaves when present 2-8 (-18) cm. long and (3-) 5-10 (-20) mm. broad, with 

 obovate to spatulate or oblanceolate obtuse blades; leaves of midstem when present 

 (4-) 5-15 (-16) cm. long and 2-10 (-12) mm. broad, linear or linear-lanceolate 

 with obtuse rarely acutish apexes; heads solitary on the stems; involucres (5-) 

 6-12 (-15) mm. high; phyllaries herbaceous, green except for the white-hyaline 

 margins below, glabrous, entire, subequal in 1 or 2 series, the outer usually but 

 scarcely imbricate, 5-12 (-15) mm. long, 1-2 (-3) mm. broad, linear-oblong or 

 linear-lanceolate with obtuse or merely acutish apexes; pales 5-8 mm. long, linear 

 with merely acute apexes, slightly dilated at the summit; corollas usually white or 

 cream-colored, only occasionally pale-lavender; pappus scales (1.5-) 2-3 (-4) mm. 

 long; achene (2-) 3-4 (-4.5) mm. long. 



In marshland and in spring seepage areas, in s.e. Okla. and the e. half of Tex., 

 w. to Taylor, Val Verde and DeWitt cos., Apr.-May (-June); Miss., Ark., Okla., 

 Tex. and La. 



We have two varieties. 



1675 



