298 CARDUACEAE. 



or nearly so, 4-6 mm. long : pappus white. — Susquehanna valley. Occasional, 

 on islands and shores. 



20. A., paniculatus Lam. Stems 6-25 dm. tall, glabrous or nearly so, panicu- 

 lately much branched: leaf-blades lanceolate to oblong-lanceolate, 7-15 cm. 

 long, acuminate at the apex, narrowed to a sessile or slightly clasping base, 

 glabrous, thin, roughish-margined, those of the cauline leaves sparingly serrate 

 in the middle, or sometimes very nearly entire, the upper and those of the 

 branches gradually smaller: heads numerous, 16-20 mm. broad: involucre 

 nearly hemispheric, 6-8 mm. high; bracts narrowly linear-lanceolate, acute or 

 acuminate, appressed, green-tipped, in 4 or 5 series: ray-flowers numerous; 

 ligules white (or faintly tinged with violet), 6-8 mm. long: pappus white or 

 nearly so. — Common, in moist thickets and ditches, 



21. A. salicifolius Lam. Stems 6-15 dm. tall, rather slender, paniculately 

 much branched, usually very leafy, glabrous, or somewhat pubescent above: 

 leaf -blades somewhat firm, lanceolate or linear-lanceolate, 5-10 cm. long, rough- 

 margined, acute or acuminate, narrowed and sessile or slightly clasping at the 

 base, entire or sparingly dentate with low teeth, glabrous or nearly so, those 

 of the lower leaves sometimes with petiole-like bases, those of the branches 

 gradually smaller: heads numerous, 16-25 mm. broad: involucre broadly turbi- 

 nate; bracts linear-oblong, appressed, in 4 or 5 series, their green tips acute 

 or obtusish: ray-flowers numerous; ligules violet, or violet-purple, or some- 

 times white, 6-8 mm. long : pappus white. — M, Occasional, in waste places 

 and on roadsides. — Limestones. 



15. EEIGERON L. Annual, biennial, or perennial caulescent herbs. 

 Leaves alternate, sometimes mostly basal: blades entire or toothed. Heads 

 solitary or numerous, conspicuously radiate. Involucres broad, many-flowered: 

 bracts narrow, the inner broader than the outer ones. Eay-flowers numer- 

 ous: corollas with a slender tube and a narrow pink, violet, purple, or white 

 ligule. Disk-corollas with a funnelform throat and a usually shorter tube: 

 lobes deltoid. Anthers as long as the filaments or longer. Stigma short. 

 Pappus of numerous capillary bristles or bristles and scales. — Fleabane. 



Plants perennial by offsets or stolons : pappus single. 



Ray-flowers less than 100 ; ligules rather wide : inflorescence simple. 



1. E. pulchcllns. 

 Ray-flowers over 100 ; ligules very narrow : inflorescence 



compound. 2. E. philadelphiciis. 



Plants annual or biennial : pappus double. 



Larger involucral bracts longer than the ligules : upper 

 stem-leaves with sharply toothed blades : ray-flowers 

 with pink ligules. 3. E. annuus. 



Larger involucral bracts shorter than the ligules : upper 

 stem-leaves with entire blades : ray-flowers with white 

 ligules. 4. E. ramosus. 



1. E. pulchellus Michx. Stems 1-5 dm. tall, villous or hirsute-villous : blades 

 of the basal leaves obovate, spatulate or elliptic: outer bracts of the invo- 

 lucre finely pubescent; inner bracts acuminate, 5-5.5 mm. long: ray-flowers 

 50-65; ligules violet or bluish-purple: disk-corollas 4-4.5 mm. long. Com- 

 mon, on shaded banks. — Spr. — Robin 's-plantain. 



2. E. philadelphicus L. Stems 1-12 dm. tall, softly hirsute: blades of the 

 basal leaves spatulate to oblong, coarsely toothed : outer bracts of the invo- 

 lucre minutely hispidulous; inner bracts acute, 2.5-3 mm. long: ray-flowers 100 

 or more ; ligules pink or rose-purple : disk-corollas 1.5-2 mm. long. — Com- 

 mon, in low pastures. — Spr. and sum. 



3. E. annuus (L.) Pers. Stems 3-12 dm. tall, loosely pubescent: blades of the 

 basal leaves oval, oblong, or lanceolate, coarsely toothed or incised: bracts of 



