1206 CARDUACEAE 



49. PSILACTIS A. Gray. 



Annual caulescent herbs, glandular, pubescent or glabrate. Leaves alternate, various, 

 those of the basal or lower stem-leaves with pinnatifid blades ; those of the upper leaves 

 often entire. Heads radiate. Involucres hemispheric : bracts in 2-3 series, wholly her- 

 baceous or with herbaceous tips. Receptacle flattish. Ray-flowers pistillate in a single 

 series. Disk-flowers more numerous that those of the ray, perfect. Stigmas with puberu- 

 lent or hispidulous appendages. Achenes narrow, pubescent, those of the ray sometimes 

 with a mere ring representing the pappus, those of the disk with a single series of short 

 hair-like bristles. 



1. Psilactis asteroides A. Gray. Stems 3-10 dm. tall, scabrous-puberulent, or 

 glabrate, branching above : leaf-blades 1-7 cm. long, narrowly spatulate and toothed at 

 the base of the stem, oblong or linear and entire above : involucres 3 mm. high, becoming 

 rather flat at maturity ; bracts oblong to linear : ray-flowers with linear ligules 4-5 mm. 

 long : achenes 2 mm. long, minutely pubescent. 



In dry soil, Texas to Arizona and adjacent Mexico. 



50. SERICOCARPUS Nees. 

 Perennial caulescent herbs. Leaves alternate : blades various, entire or toothed. 

 Heads radiate, in corymbs. Involucres ovoid to campanulate or cylindric, several-flow- 

 ered : bracts leathery, in few series, with erect or spreading tips. Receptacle naked, pitted. 

 Ray-flowers pistillate, with white or pink ligules. Disk-flowers chiefly perfect, with yel- 

 lowish or purplish corollas. Anthers entire and obtuse at the base. Style-branches with 

 narrow appendages. Achenes flattened, l-nerved on each side. Pappus of numerous 

 scabrous bristles, the inner ones longer. 



Leaf-blades entire. 



Foliage glabrous or nearly so. 1. S. linifolius. 

 Foliage manifestly pubescent. 



Bracts of the involucres obtuse, firm : peduncles rigid, stout. 2. S. bi/olialus. 



Bracts of the involucres acute, lax : peduncles weak, slender. 3. S. aciitisquamotus. 



Leaf-blades toothed. 4. S. asteroides. 



1. Serlcocarpus linifolius (L. ) B.S.P. Stems often tufted, 2-7 dm. tall, glabrous 

 or nearly so. Leaf-blades spatulate or linear-spatulate at the base of the stem to linear 

 above, 2-6 cm. long, entire, sessile or short-petioled : involucres narrowly cylindric, 5-7 

 mm. high ; bracts ovate-oblong, to linear-oblong, obtuse, often with erose green tips : ray- 

 flowers with linear involute ligules : pappus whitish, copious. [»§. solidagineus Nees.] 



In sandy soil, Canada, south to Georgia. Ohio and Louisiana. Summer and fall. 



2. Serlcocarpus bifoli^tus (Walt.) Porter. Stems cinereous-pubescent, 3-7 dm. 

 tall, sometimes branched below. Leaf-blades spatulate to obovate, 1-3 cm. long, obtuse or 

 apiculate, vertical, sessile : involucres about 6 mm. high, cylindric ; bracts ovate to linear- 

 oblong, obtuse, sometimes minutely pubescent : pappus white, copious. [S. tortifolins 

 Nees.] 



In dry sandy pine lands, Virgina to Florida and Louisiana. Summer and fall. 



3. Serlcocarpus acutisquamosus (Nash) Small. Similar to iV. bifoUatus in habit, 

 but less robust. Leaf-blades oblong-spatulate, 1-3.5 cm. long, rather weak, acutish or 

 apiculate, entire, scabrous, sessile : involucres narrowly cylindric or cylindric-turbinate, 

 6.7 mm. high ; bracts narrowly linear-lanceolate, acute, the outer ones rather densely pu- 

 bescent : pappus white, copious. ^S. bifoUatus acutisquamosus 'Sash.l 



In pine lands, peninsular Florida. Summer. 



4. Serlcocarpus asteroides (L. ) B.S.P. Stems 3-8 dm. tall, glabrous at least to 

 the sometimes viscid-pubescent peduncles. Leaf-blades 4-15 cm. long, toothed, those of 

 the basal and lower stem-leaves spatulate, oblong or oval, those of the upper stem- 

 leaves broadest at or above the middle or sometimes lanceolate : involucres 6-9 nun. 

 high, cylindric or oblong-cylindric ; bracts ovate to linear, with appressed or spreading^ 

 green tips : ray-flowers with whitish ligules 6-8 mm. long. [S. conyzoides Nees.] 



In rocky woods, Maine to Ohio, south to Florida to Alabama. Summer. 



51. ASTER L.i 



Perennial branching glabrous or pubescent herbs, various in habit, but seldom annual, 

 unbranched, shrubby or spinescent. Leaves alternate : blades broad or narrow, often en- 



1 Contributed by Professor Edward S. Burgess. 



