With about 200 species, nearly cosmopolitan, Erigeron is a difficult group of 

 daisy like plants. 



I. Plants of east and southeast Texas and eastern Oklahoma (2) 



1. Plants of central Texas and central Oklahoma westward (4) 



2(1). Trailing plants of sandy soil or salt marshes near the coast; stems often 

 subrhizomatous 1. E. myrionactis. 



2. Erect plants of various habitats (3) 



3(2). Plants with superficial rhizomes; disk corollas 4.5-6 mm. long; rays 1 mm. 

 broad or broader 2. E. pulchellus. 



3. Rhizomes absent; disk corollas 2.5-3.2 mm. long; rays 0.6 mm. broad or 



narrower 3. E. philadelphicus. 



4(1). Pistillate corollas very numerous, filiform, with very narrow short erect 

 rays; rayless pistillate flowers wanting; inflorescence racemiform, 

 the peduncles erect, or the head solitary 4. E. lonchophylliis. 



4. Pistillate corollas few to numerous, the rays well-developed and spreading (5) 



5(4). Cauline leaves usually much-reduced, mostly linear or oblanceolate; plants 

 relatively low and often spreading or trailing 5. E. flagellaris. 



5. Cauline leaves ample, usually lanceolate or broader; plants when well- 



developed tall and erect (6) 



6(5). Hairs of the involucre with black crosswalls near the base; rays white; 

 leaves hairy; pappus simple or nearly so 6. E. Coulteri. 



6. Hairs of involucre without black crosswalls; rays, leaves and pappus various 



(7) 



7(6). Rays mostly 2-4 mm. wide; basal leaves tapering to the petiole 



7. E. peregrinus. 



7. Rays mostly 1 mm. wide or less (8) 



8(7). Rays very numerous (over 150) and narrow, about 0.2-0.6 mm. wide; disk 

 corollas mostly 2.5-3.2 mm. long 3. E. philadelphicus. 



8. Rays not excessively numerous, about 1 mm. wide; disk corollas 3.5-4.4 mm. 



long; stem and involucre glandular or viscid 8. E. formosissimus. 



1. Erigeron myrionactis Small. 



Perennial with stems stoloniferous or subrhizomatous in coastal sands, rooting 

 at the nodes, prostrate; stems often to 1 m. long; herbage with spreading hairs; 

 leaves obovate to spatulate or cuneate, 2-8 cm. long, 5-25 mm. broad, coarsely 

 few-toothed near the end; heads solitary, borne about 1 dm. above ground; rays 

 very numerous, white, 5-7 mm. long, about 0.3 mm. broad; disk corollas 3.5-4.5 

 mm. long; pappus of ray and disk essentially similar, simple, of about 20 to 25 

 fragile capillary bristles. 



Frequent in coastal sand and salt marshes in s.e. Tex. and the Rio Grande 

 Plains, spring-fall; La., Tex. and Tam. 



2. Erigeron pulchellus Michx. Robin's-plantain. 



Hirsute short-lived erect perennial, 15-60 cm. tall, with fibrous root system 

 and superficial rhizomes; basal leaves oblanceolate to suborbicular, tapering to 

 short subpetiolar bases, 2-13 cm. long, 6-50 mm. broad, shallowly toothed above 

 the middle or subentire; stem leaves lanceolate or oblong to more commonly 

 ovate, obtuse or rounded to slightly acute at apex, entire or nearly so, the middle 

 and lower leaves 2-7 cm. long and 6-20 mm. broad; heads few in a fiat-topped 

 arrangement; disk corollas 4.5-6 mm. long or usually longer; rays 1 (-2) mm. 

 broad, 6-10 mm. long; pappus simple, of capillary bristles, alike in ray and disk. 



Rare in open places and in woods on stream banks, deep sandy soil, e. Okla. 

 {Waterfall) and e. and s.e. Tex., Apr.-May; most of e. U.S. 



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