310 CAEDUACEAE. 



lieaves green ; blades repand-dentate : stems furrowed, green. 1. M. reniformis. 

 Leaves glaucous ; blades angulate-lobed : stem terete, glaucous. 2. M. atriplicifolia. 



1. M. reniformis (Muhl.) Eaf. Stems 9-30 dm. tall: blades of the cauline 

 leaves reniform, 10-60 cm. wide: involucral bracts 8-11 mm. long: achenes 

 about 5 mm. long. — Susquehanna valley. Occasional, in woods and thickets. 

 — Schists. — Great indian-plantain. 



2. M. atriplicifolia (L.) Eaf. Stems 9-20 dm. tall: blades of the cauline 

 leaves ovate to triangular, or narrower above, angulate-lobed or sharply and 

 coarsely toothed: involucral bracts 8-11 mm. long: achenes 4-4.5 mm. long. — 

 Occasional, in thickets. — Pale indian-plantain. 



46. SYNOSMA Eaf. Perennial herbs. Leaves alternate: blades tri- 

 angular to hastate, toothed. Heads corymbose. Involucre nearly cylindric: 

 bracts narrow. Disk-corollas with lanceolate lobes shorter than the funnel- 

 form throat. Filaments enlarged below the anthers. Achenes ribbed, glabrous. 



1. S. suaveolens (L.) Britton. Plants 6-15 dm. tall: leaves numerous; blades 

 hastate, 8-20 cm. long, serrate or dentate-serrate: larger bracts of the invo- 

 lucre 10-11 mm. long: corollas 11-12 mm. long: achenes slender, 7-8.8 mm. 

 long. — M. S. Frequent, in thickets and on shaded banks. — Limestones, 

 schists. — Sum. 



47. SENECIO [Tourn.] L. Annual or perennial herbs. Leaves alternate : 

 blades entire, toothed, pinnatifid, or pinnately parted. Heads solitary or many. 

 Involucre campanulate to cylindric: bracts flat. Disk-corollas yellow with a 

 funnelform throat and triangular or ovate lobes. Filaments often enlarged 

 below the anthers. Achenes 5-10-ribbed, pubescent or pappillose. — Spr. — 

 Squaw-weed. Eagwort. Eagweed. Groundsel. 



Blades of the basal leaves cordate or subcordate at the base. 1. S. aureus. 



Blades of the basal leaves narrowed at the base. 



Blades of the basal leaves prevailingly spatulate : achenes 



glabrous. 2. S. oiovatus. 



Blades of the basal leaves prevailingly oblong : achenes 



pubescent. 3. S. Balsamltac. 



1. S. aureus L. Plants 3-7 dm. tall: blades of the basal leaves 2-12 cm. long, 

 rounded at the apex : involucres 6-7 mm. long ; bracts linear, fully 1 mm. wide : 

 ligules narrow, 5.5-7.5 mm. long. — Common, in low grounds and swamps. 



2. S. obovatus Muhl. Plants 1-5 dm. tall: blades of the basal leaves spatu- 

 late to obovate, coarsely toothed or some of them lyrate-pinnatifid : involucres 

 4-5 mm. long; bracts narrowly linear or subulate-linear: ligules 5-7 mm. long. 

 — N. M. Frequent, in thickets and dry hillsides. — Sandstones and shales, 

 Mmestones. 



3. S. Balsamitae Muhl. Plants 2-6 dm. tall: blades of the basal leaves oblong 

 to oblong-spatulate, toothed: involucres 4-5 mm. long; bracts narrowly linear 

 or nearly linear: ligules 4-6 mm. long: achenes about 3 mm. long. — Common, 

 in dry soil and thickets and on roadsides. 



48. XERANTHEMUM L. Annual herbs. Leaves alternate: blades nar- 

 row, entire. Heads erect. Involucres campanulate to cylindric: bracts firm, 

 in several series, the outer short and appressed, the inner ones elongate, spread- 

 ing, resembling ligules of a ray. Marginal-corollas 2-lipped. Central-corollas 

 with a short tube and an elongate throat: lobes mostly narrow. Achenes nar- 

 row. Pappus of 5, or rarely of more, elongate scales. 



1. X. annuum L. Plants mostly 3-10 dm. tall, the stem and branches floc- 

 cose: leaf-blades linear-spatulate to linear, more copiously pubescent beneath 



