Prenanthes alba
 
White Lettuce

Whole Plant

3.2 km North of Highway # 3 on Silica Sands Road,
33 km East of Hudson Bay
09-August-2016

Note the basal leaves are cordate- or hastate-based, abruptly joining the stalk.  Note also the tuberous-thickened taproot.

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Alba: Answers to key questions in Budd's Flora leading to this species. 
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basal leaves cordate- or hastate-based, abruptly joining stalk;  NOT [basal leaves tapering to winged stalks]

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leaves lobed or cleft; NOT [leaves dentate]

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flowers heads nodding; NOT [flower heads erect]

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bracts of involucre not hairy

 

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Prenanthes: Answers to key questions in Budd's Flora and Flora of Alberta leading to this genus. 
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juice milky; NOT [juice watery]

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stem not diffusely branched

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plants essentially glabrous below the inflorescence; NOT [plants hairy]

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plants with normal stem leaves; NOT [plants with leaves all basal], NOT [stem leaves few, mostly linear or reduced to scales]

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stems leafy throughout or at least to midway up the stem; NOT [stems leafy at the base only, leaves mostly basal]

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heads few to many, rarely solitary; NOT [heads solitary]

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involucre of two or more series; NOT [involucre uniseriate]

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involucre usually of unequal bracts; NOT [involucre of equal bracts]

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bracts of involucre broad; NOT [bracts of involucre narrow]

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bracts of involucre colored; NOT [bracts of involucre green]

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flowers all ligulate (ray)

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flowers all perfect; NOT [flowers pistillate or neuter]

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flowers white or purplish

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stamens united to form a tube around the pistil

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pappus consisting of bristles only; NOT [pappus of minute scales or none], NOT [pappus double, the outer ring consisting of 5 small scale-like appendages, the inner ring bristles], NOT [pappus scale-like at the base, with plumose terminal bristles]

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pappus bristles simple; NOT [pappus bristles plumose (branched)]

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pappus brownish or tawny; NOT [pappus white]

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achenes not flattened; NOT [achenes flattened, at least twice as wide as thick]