Lactuca serriola
Citation:
L., Cent. 2. Pl. 29 (1756).
Synonymy: L. scariola L., Sp. Pl. edn 2:119 (1763); L. virosa sensu J. Black, Fl. S. Aust. 661 (1929), non L.
Common name: Prickly lettuce, compass plant, milk thistle.
Description:
Biennial 1-2 m high; stems erect, seldom branched below the inflorescence, glabrous to setose, pale; leaves oblanceolate to oblong, usually pinnatifid to pinnatisect, rarely more or less entire, 3-18 cm long, to 6 cm wide, usually minutely spinulose-denticulate along the margin, spinulose to setose on the mid-vein; cauline leaves amplexicaul with acute to obtuse auricles, twisted at the base into a roughly vertical plane; panicle pyramidal with spreading branches.
Capitula pedicellate, solitary in the axils of reduced leaves and terminating the ultimate branches; involucres 3- or 4-seriate, 6-9 mm long at flowering, green to reddish; inner bracts accrescent to 12 mm, spreading or reflexed in fruit; florets 7-18, slightly exceeding the involucre.
Achenes 6-8 mm long; body 3-4 mm, obovate, 5-9-ribbed on each face, minutely setulose above, grey-brown; pappus bristles c. 3 mm long.
Published illustration:
Cunningham et al. (1982) Plants of western New South Wales, p. 719.
Distribution:
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Roadsides, gardens, cultivated fields, irrigation land; also along watercourses and disturbed sites in bushland.
All States.
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Conservation status:
naturalised
Flowering time: Sept. — April.
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SA Distribution Map based
on current data relating to
specimens held in the
State Herbarium of South Australia
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Biology:
Lactuca sativa L., the garden lettuce, is closely related to L. serriola it may persist on and near former cultivation.
Author:
Not yet available
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