Clammy Sow-thistle

Photos for Clammy Sow-thistle

Family: Daisy (Asteraceae syn. Compositae)

Scientific Name:

Sonchus tenerrimus

Clammy Sow-thistle plant
Photo: A J Brown

Other Common Names:

Slender Sow Thistle, Mediterranean Sow Thistle

Status:

Native to Europe and south-west Asia. Naturalised in Western Australia, South Australia and Victoria.

Plant Description:

Annual, biennial or sometimes perennial to 80 cm tall. The basal rosette of leaves is not always distinctive, often merging into the stem leaves. Leaves are thin and soft, 4-20 cm long and 2-9 cm wide, lanceolate (lance-shaped) to oblanceolate (backwards pointed lance), hairless and are dark dull green with pale or purplish veins. Leaves are generally moderately to deeply lobed, with the terminal lobe not particularly larger than the other lobes and each lobe strongly constricted at its base or sometimes narrow-linear throughout. Leaf lobe margins are irregularly toothed but not spiny.

Flower stems and involucre (flower cup) are hairless or have gland-based hairs. Involucre 10-13 mm long and ‘petals’ (each is actually a single flower) are 8-9 mm long and yellow. The fruit is a cypsela or achene (dry, indehiscent and one-seeded), obovoid in shape, 2.5-4 mm long, moderately compressed, abruptly tapering at the base, wrinkled all over and 3-ribbed on each face.

Habitat:

Scattered weed of disturbed areas, roadsides and waste places and on sub-saline flats and swamp margins.

Region	Salinity Class	Waterlogging Class
Mallee, Loddon Murray, Central and Northern, Wimmera, Western, Gippsland	S0, S1	W1, W2

Comments:

This species is probably more widespread than has been recorded, owing to its superficial similarity to Common Sow-thistle (Sonchus oleraceus). Some botanists suggest that Common Sow-thistle may in fact be a polyploid, stable hybrid derived from Clammy Sow-thistle and Rough Sow-thistle (Sonchus asper). Clammy Sow-thistle belongs to a group of mainly yellow-flowered daisies in the Tribe Lactuceae. The plants in this tribe are characterised by having a basal rosette of leaves (flat-weeds), milky sap in their stems and their flower-heads consisting entirely of ray florets (i.e. no ‘eye’ to the daisy). See Key to Yellow Daisy Flat-weeds.

Photos for Clammy Sow-thistle

Upper section of Clammy Sow-thistle leaf Photo: A J Brown	Toothed margin of Clammy Sow-thistle leaf Photo: A J Brown
Clammy Sow-thistle flower buds Photo: A J Brown	Flowers of Clammy Sow-thistle Photo: A J Brown

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