Sonchus asper
 
Prickly Sow-Thistle

Middle Leaf Bottom

Dunnet Regional Park
19-July-2013

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Asper: Answers to key questions in Budd's Flora and Flora of Alberta leading to this species. 
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annuals growing from deep taproots; NOT [perennials from creeping rootstocks]

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ears at base of clasping leaves rounded; NOT [ears at base of clasping leaves acutely pointed]

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heads 1.5-2.5 cm wide in flower; NOT [heads 3-5 cm wide in flower]

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fruiting involucre 9-13 mm high; NOT [fruiting involucre 14-24 mm high]

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fruiting involucre glabrous

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achenes 3-ribbed on each side, not wrinkled; NOT [achenes striate and transversely wrinkled]

 

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Sonchus: Answers to key questions in Budd's Flora and Flora of Alberta leading to this genus. 
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plants of various habitats; NOT [plants of dry habitats]

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juice milky; NOT [juice watery]

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NOT [stem diffusely branched]

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plants with normal stem leaves; NOT [plants with leaves all basal or with a few reduced leaves on the stem]

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leaves broader and leaf-like; NOT [leaves narrowly linear or scale-like]

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

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involucre of 2 or more series; NOT [involucre uniseriate or biseriate]

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florets all ligulate (ray)

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florets all perfect

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florets yellow

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stamens united to form a tube around the pistil

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achenes beakless; NOT [achenes beaked, the pappus born on a disc at the tip]

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

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pappus well developed, at least in part of capillary bristles; NOT [pappus of minute scales or none]

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pappus simple, consisting of bristles only; NOT [pappus double, the outer ring consisting of 5 small scale-like appendages, the inner ring bristles]

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

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pappus white; NOT [pappus brownish or tawny]