1204 CAKDUACEAE 



Bracts of the involucre broadest below the middle, acute. 2. B. astewides. 



Bracts of the involucre broadest above the middle, obtuse or mucronulate. 3- B. latisquama. 



b. Leaf-blades decurrent on the stem as broad wings. H. B. decurrens. 



1. Boltonia diffusa Ell. Stems slender, 1-2 m. tall, much-branched : leaf -blades 

 linear to linear-subulate, or broader near the base of the stem, 2.5-8 cm. long, acute : invo- 

 lucres 2-2.5 mm. high ; bracts numerous, linear or nearly so, acute: disk about 4 mm. 

 broad : ray-flowers numerous, with white ligules : achenes barely 1.5 mm. long. 



In low grounds, South Carolina and Illinois, south to Florida and Texas. Fall. 



2. Boltonia asteroides L'Her. Stems 1-2 m. tall, branching above : leaf -blades 

 linear, oblong or slightly broadest above the middle, 3-12 cm. long, acute, sessile : invo- 

 lucres 2.5-3 mm. high; bracts acute, broadest below the middle : disk 6-12 mm. broad: 

 ray-flowers numerous, with white or pale ligules : achenes fully 1.5 mm. long. 



In low grounds and along streams, New Jersey to Minnesota, south to Florida, Louisiana and 

 Nebraska. Summer and fall. 



3. Boltonia latisqu^ma A. Gray. Stems much branched, 1-2 m. tall : leaf-blades 

 linear or nearly so, 2-10 cm. long, acute, sessile : involucres about 4 mm. high ; bracts 

 oblong to rhomboidal above the middle, obtuse or mucronate : ray-flowers numerous, with 

 violet-blue ligules : achenes obovate, 1.5 mm. long: pappus-bristles nearly as long as the 

 achene. 



In river valleys, Minnesota to Kansas and Arkansas. Summer and fall. 



4. Boltonia decilrrens (T. & G.) "Wood. Similar to B. latisquama in habit, but 

 stouter and taller. Stem more or less branched, conspicuously winged by the decurrent 

 leaf-blades, glabrous or nearly so : leaf-blades spatulate to narrowly oblong or linear-oblong, 

 5-15 cm. long, obtuse or acutish, undulate, sessile and decurrent: involucres 3-3.5 mm. 

 high ; bracts linear-spatulate to linear, acute or acuminate : ray-flowers numerous, with 

 violet or pale ligules : achenes cuneate, about 2 mm. long : pappus-bristles somewhat 

 shorter than the achene. 



In low grounds, Illinois to Missouri and Arkansas. Summer and fall. 



44. KEERLIA A. Gray. 



Annual or perennial caulescent pubescent herbs. Leaves alternate : blades broadest 

 above the middle or oblong to linear, entire or serrulate. Heads radiate, few, slender- 

 peduncled. Involucres narrow, few-flowered : bracts tliin, scarious-margined, in few series, 

 pointed. Receptacle flat. Ray-flowers 5-15, pistillate. Disk-flowers several, perfect. 

 Stigmas with short or long appendages. Achenes flattened, 2-3-nerved, those of the .disk 

 mostly imperfect. Pappus a crown-like border sometimes evanescent. 



Annual : foliage minutely and somewhat scabro-pubescent : leaf-blades ciliate. 1. K. bellidijolia. 



Perennial : foliage hispid : leaf-blades spinulose-serrulate. 2. K. effusa. 



1. Keerlia bellidifolia Gray & Engelm. Annual, minutely pubescent. Stems 1-2 

 dm. tall, sometimes diffusely branched : leaf-blades spatulate below to linear above, 1-3 

 cm. long, acute or acuminate, entire : involucres narrowly campanulate, 2.5-3 mm. high ; 

 bracts oblong-lanceolate to linear-oblong, cuspidate, scarious-margined : ray-flowers 6-15 ; 

 ligules blue : achenes oblong-clavate, 2 mm. long, slightly flattened. 



In moist soil, Texas. Spring and summer. 



2. Keerlia effusa A. Gray. Perennial, hispid. Stems 3-7 dm. tall, simple below, 

 effusely branched above, the branches usually filiform : leaf-blades oblong to ovate, 1-3 cm. 

 long, acute or cuspidate, revolute, sessile and partly clasping : involucres oblong, 4 mm. 

 high ; bracts oblong-ovate to narrowly oblong, cuspidate, scarious-margined : ray-flowers 

 4-5; ligules white, narrowly oblong : achenes obovoid, 1-1.5 mm. long, flattish, the mar- 

 gins with 1 or 2 nerves. 



On hillsides, Texas. Spring and summer. 



45. THUROVIA Rose. 



Low annual herbs, with spreading branches, and glabrous. Leaves alternate : blades 

 narrow, inconspicuous. Heads mostly solitary and sessile in the axils of the leaves, dis- 

 coid, few-flowered. Involucres somewhat distended in age : bracts in 2 series, usually 8, 

 those of the inner series fewer than those of the outer. Flowers perfect, fruit producing. 

 Corollas funnelform at the throat, 5-lobed. Filaments not appendaged. Stigmas short, 

 witli slender appendages. Achenes turbinate, silky, nerveless. Pappus of about 10 acu- 

 minate scales. 



