CARDUACEAE 1231 



or purplish ligules. Disk-flowers several, perfect, the corollas usually with 4 lobes. An- 

 thers obtuse at the base. Stigmas flattened, with short appendages. Achenes flattened, 

 often pubescent. Pappus of many brittle hair-like bristles in one series. 



Inner bracts of the involucre copiously pubescent. 1. L. linifolium. 

 Inner bracts of the involcure glabrous or nearly so. 



Stems diffusely branched at the base : ray-flowers with purplish ligules. 2. L. divaricatum. 

 Stem usually simple below the inflorescence : ray-flowers with white ligules. 



Stem-leaves with mainly entire or merely few-toothed blades. 3. L. Canadense. 



Stem-leaves with mainly pinnatifid or pi'nnatifld-toothed blades. 4. L. Bonariense. 



1. Leptiloii linifolium (Willd.) Small. Stems 2-7 dm. tall, hirsute, racemose or 

 paniculate above. Leaf-blades narrowly spatulate to linear, 1.6-10 cm. long, the lower 

 ones incised orlaciniate, slender-petioled, the upper entire or sparingly toothed : involucres 

 2-3 mm. high ; bracts linear to linear-subulate. 



In waste places, South Carolina to Florida and Alabama. Spring to fall. 



2. Leptiloii divaricatum (Michx. ) Kaf. Stems diffusely much branched, 1-3 dm. 

 tall, finely hirsute and somewhat cinereous. Leaf-blades narrowly linear to subulate, 1-4.5 

 cm. long, entire : invplucres 1.5-2 mm. high ; bracts narrowly linear to linear-subulate 

 ray-flowers with purplish ligules which rarely surpass the style-branches. 



In dry soil, Minnesota to Illinois, Alabama, Nebraska and Texas. Summer and fall. 



3. Leptiloii Canad6nse (L.) Britton. Stems glabrate or sparsely hirsute, 3-20 dm. 

 tall, or sometimes diminutive, simple to the paniculate inflorescence : leaf-blades linear or 

 nearly so, or spatulate near the base of the stem, entire or coarsely few-toothed, conspicu- 

 ously ciliate near the base : heads normally very numerous : involucres 3-3.5 mm. high ; 

 bracts in 1 series, linear-subulate to linear, the outer ones often pubescent : corollas of the 

 disk-flowers usually 4-lobed : ray-flowers with white or whitish little-exserted ligules. 



In various situations, nearly throughout North America. Also widely distributed in Europe and 

 South America. Spring to fall. 



4. Leptilon Bonariense (L. ) Small. Similar to L. Canadense in habit : leaf-blades 

 finely pubescent, mainly pinnatifid or pinnatifid-toothed, but those of the branches or near 

 the inflorescence entire or nearly so : involucres 3-4 mm. high ; bracts in 3 series : corollas 

 of the disk-flowers usually 5-lobed ; ligules of the ray-flowers scarcely, if at all, exserted. 



In waste ground. Pensacola, Florida. Introduced from tropical and South America. 



55. DOELLINGERIA Nees. 



Perennial caulescent herbs. Leaves alternate : blades firm, entire, ciliate, sessile. 

 Heads in corymbose cymes, several or many. Involucres campanulate to hemispheric, 

 several- to many-flowered : bracts imbricated in 2-4 series, narrow, appressed, neither 

 herbaceous nor foliaceous at the tip. Keceptacle pitted. Ray-flowers few or several, pis- 

 tillate : ligules white or nearly so. Disk-flowers perfect : corollas narrow, expanded into a 

 5-lobed throat. Anthers obtuse at the base. Stigma-appendages typically ovate or sub- 

 ulate. Achene nearly terete or flattened, sometimes nerved, slightly broadened upward. 

 Pappus double, the outer series of short bristles or scales, the inner of capillary bristles, 

 all or some of them thickened at the tip. 



Ray-flowers with linear ligules over 10 mm. long : inner bracts of the involucre acuminate. 



1. D. reticulata. 



Ray-flowers with oblong ligules less than 10 mm. long : inner bracts of the invo- 

 lucre merely acute or obtuse. 

 Achenes nearly terete, ribless, less than 1 mm. wide. 



Ovary and achene pubescent : outer involucral bracts ciliate near the tip. 



Involucral bracts acute or acutish, the inner linear, ciliate at the tip. 2. D. umbellata. 

 Involucral bracts obtuse, the inner oblong, eciliate. 3. D. humilis. 



Ovary and achene glabrous : outer involucral bracts ciliate all around. 4. D. sericocarp&ides. 



Achenes much flattened, ribbed, over 1 mm. wide. 5. D. inflrma. 



1. Doellingeria reticulata (Pursh) Greene. Stems 3-12 dm. tall, finely soft-pubes- 

 cent, fastigiate-corymbose above : leaves rather numerous ; blades oblong or oval, varying 

 to oblong-obovate or narrowly oblong, 4-8 cm. long, or shorter on the upper part of the 

 stem, obtuse or merely acutish, entire or essentially so, sometimes undulate, prominently 

 fine-reticulate beneath, manifestly reticulate above : heads few or numerous, slender-pe- 

 duncled : involucres about 6 mm. high ; bracts linear to narrowly linear-lanceolate, acute 

 or acuminate, the tips erect : ray-flowers 9-13 ; ligules 11-15 mm. long : achenes 4 mm. 

 long, pubescent. 



In low pine lands, South Carolina to Florida. Spring and summer. 



2. Doellingeria umbellata (Mill. ) Nees. Stems 6-25 dm. tall, glabrous or somewhat 

 pubescent above, corymbosely branched : leaves numerous ; blades membranous, narrowly 



