860 CARDUACEAE 



1. S. grindeUolcles, 



2. S. aberrans. 



linear-lanceolate, acuminate, squarrose; Hgules numerous, 1-1.5 cm. long. Aplo- 

 pappus ciliatus DC. River banks and hillsides: Mo.— Tex. — Colo. Plain, 



17. SIDERANTHUS Nutt. Iron Plant, 



Perennial or annual herbs, rarely suffruticose at the base. Leaves alternate. 

 With spinulose-tipped lobes or teeth. Heads radiate, or in two species discoid. 

 Involucres campanulate or hemispheric, many-flowered; bracts well imbricate, 

 in 3-5 series, appressed or with loose tips, green; receptacle flat, naked, usually 

 pitted, Ray-flowers pistillate, or in two species wanting; ligules yellow. Disk- 

 corollas yellow; tube scarcely dilated into a distinct throat. Anthers obtuse at 

 the base. Style-branches flattened, with lanceolate appendages. Aehenes ob- 

 tuse, pubescent, mostly 8-10-nervea. Pappus of many unequal hair-like bristles 

 in 1-3 series, persistent. 



Leaves spinescent-toothed, not pinnatiP.d. 



Heads discoid; perennials, with woody caudex. 

 Heads peduiicled. 

 Heads sessile. 



Heads radiate; annuals. 



Leavas oblanceolate, spinulose-tipped; plant more or less viscid. 3. S. annuus 

 Leaves hnear-oblanceolate, bristle-tipped; plant stri^ose. 4. 5. gracilis 



Leaves pinnatifid; perennials, with a short woody base; aehenes somewhat flattened 



btem more or less floccose or cinereous, especially when young. 



Plant cinereous pubescent, more or less glandular. 5 s. australis 



Plant more or less floccose, not at all glandular. 6* S spinulosus 



Plant neither floccose nor cinereous. ' ' ^ 



Plant perfectly glabrous or sparingly glandular-puberulent. 7. S. glaberrhnus. 

 Plant finelj puberulent, or hispid. 



Heads hemispheric; bracts sUghtly glandular. R. S. puberulus 



Heads somewhat turbinate; bracts densely glandiUar-puberulent. 



9. S. turbinellus, 



1. S. grindelioides (Nutt.) Rydb. Low cespitose perennial; stems erect, 

 1-3 dm. high, somewhat pubescent; leaves thick, obovate or oblanceolate, spinu- 

 lose-scrrate, 1-3 cm. long, more or less crisp-hirsute or strigose; involucres hemi- 

 spheric, 6-7 mm. high, 1 cm. broad; bracts lanceolate, puberulent; aehenes some- 

 what flattened. Eriocarpnrn grindelioides Nutt. Aplopappus Nidtallii T. & G 



Dry plains and hills: Sask.— Neb.— N.M.— Ariz.— Nev.—Alta. PlainSub- 

 rnont. Je-Au. 



2. S. aberrans (A. Nels.) Rydb. Perennial, with a creeping rootstock; stems 

 erect, 5-10 cm. long, glandular-pubescent; leaves obovate or oblong, glandular- 

 puberulent, or the lower ovate, 1-3 cm. long, sparingly cuspidate-toothed on the 

 margins; heads 1-4, subsessile, 9-14 mm. high; bracts broadly linear, acute, 

 green and glandular-viscid at the apex; aehenes cylindric-fusiform, 3 mm. long 

 MacTonema aberrans A. Nels. Mountains: Ida. MonL Au. 



3. S. annuus Rydb. Annual; stem simple below, branched above, more or 

 less glandular-pubescent; leaves oblanceolate, spinulose-dentate, 3-6 cm. long; 

 heads cor^-mbose; involucres hemispheric, about 8 mm. high, viscid-puberulent; 

 bracts linear-lanceolate, acuminate; ligules light yellow, 5-6 mm. long; aehenes 

 obtusely 5-angled. Aplopappus rubiginosus A. Gray, in part. Sandy places: 

 Neb.— Colo.— Tex. Plain. ^ i- j i 



4. S. gracilis (Nutt.) Rydb. Annual, branched, becoming woody at the 

 base; stems 2-4 dm. high, hispid-strigose; leaves Hnear-oblanceolate to spatulate 

 in outline, coarsely dentate or somewhat pinnatifid; teeth tipped with lone 

 bristles; involucres 6 mm. high; bracts linear, spinulose-tipped, strigose; ligules 

 5-6 mm^long.hght yellow. Dieteria gracilis Nutt. A. gracilis A. Gvviy. Dry 

 hills: s Colo.— Tex.— Ariz.— Calif.; Mex. Son.—SubmonL My-S, 



5. S, australis (Greene) Rydb. Stem 2-4 chn. high; leaves pinnatifid 2-7 

 cm. long; segments linear or oblong, spinulose-tipped, entire or toothed; involucres 

 b mm. high; bracts linear, puberulent, spine-tipped; ligules 5-6 mm. lone yellow 

 Eriocarpum australe Greene. Dry soil : Colo.— Tex.— N.M.— Ariz — e Utah • Mex" 



Son. — Suhmont. Ap-Je. 



spinulosus (Pursh) Sweet. Stem 1-4 



, pinnatifid; segments linear or oblom 



