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Published In: Species Plantarum 2: 798. 1753. (1 May 1753) (Sp. Pl.) Name publication detailView in BotanicusView in Biodiversity Heritage Library
 

Project Name Data (Last Modified On 8/11/2017)
Acceptance : Accepted
Project Data     (Last Modified On 7/9/2009)
Status: Native

 

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1. Prenanthes alba L. (white lettuce, rattlesnake root, white snakeroot)

Nabalus albus (L.) Hook.

Pl. 261 a, b; Map 1090

Stems 30–170 cm long, usually relatively stout, glabrous or sparsely and inconspicuously pubescent with short, curled hairs toward the tip, usually purplish-tinged or with dark purple mottling, often somewhat glaucous. Leaves variable, glabrous or the undersurface sparsely and inconspicuously pubescent with short, curled hairs, often somewhat glaucous. Basal and lower stem leaves usually long-petiolate, the blade 4–30 cm long, usually broadly triangular, sometimes with a pair of triangular basal lobes, the margins often with few to several broad, spreading teeth. Median and upper leaves gradually reduced, with progressively shorter petioles (often sessile toward the stem tip), the blade entire or nearly so or finely to coarsely toothed or shallowly pinnately lobed, triangular to ovate or ovate-elliptic. Inflorescences usually elongate panicles, narrow to broad, the heads tending to be clustered toward the branch tips, terminal and often also from the upper leaf axils, sometimes with additional small clusters of heads below the main inflorescence, the heads commonly nodding. Involucre 10–14 mm long, the inner bracts 7–9(–11), rounded to sharply pointed at the often somewhat incurved tip, glabrous (the margins rarely microscopically hairy near the tip), often somewhat purplish-tinged, appearing somewhat glaucous or minutely pebbled (the effect caused by microscopic white papillae on the outer surface). Ligulate florets 7–13. Corollas 9–15 mm long, white to pale pink or lavender, sometimes reddish- or purplish-tinged toward the base. Pappus 6–7 mm long, orangish brown to reddish brown. Fruits 4–6 mm long, light brown to yellowish brown. 2n=32. July–September.

Uncommon, known mostly from historical collections from the northeastern quarter of the state (northeastern U.S. west to North Dakota and Arkansas; Canada). Bottomland forests, mesic upland forests, ledges of bluffs, and banks of streams and rivers.

As in P. altissima, some populations in the eastern portion of the range of P. alba have the pappus straw-colored to light yellow.

 
 


 

 
 
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