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Key for Yellow Daisy Flat Weeds

A number of flat-weeds with yellow daisy type flowers grow on moist to wet depressions, flats or swamps or on sand dunes with some tolerance to salinity. The following key is provided to assist in the identification of these species. Only four of these are native to Australia; Native Yam Daisy, Native Picris, Native Sow-thistle and Dune Thistle. Other daisies in this group but not in this key grow in agricultural soils or in forested or alpine regions and would not normally be encountered on wet or saline ground, though they may grow on roadsides.

The typical daisy ‘flower’ is actually a compound head of many individual flowers, comprising of a central disk or ‘eye’ of tubular flowers, surrounded by ligulate flowers that form a flattened ray of ‘petals’ (e.g. Capeweed with its black or dark brown tubular disk and yellow ray). However, many daisies only have tubular flowers (e.g. Water-buttons) and not both. All the species in the following key consist of ligulate flowers only, have a basal rosette of leaves (flat-weeds), exude a milky juice (latex) from their broken stems and belong to the Tribe Lactuceae (syn. Cichorieae).

1.Leaves all at the base (radical) with leafless stems
1.Leaves both basal and along the stems
2.Stems unbranched and without small leafy scales
2. Stems generally simply branched and slightly scaly
3.Leaves and lower parts of stems with short hairs
Hairy Hawkbit
Leontodon taraxacoides)
3.Leaves and lower parts of stems without hairs or almost so
4.Leaf margins without lobes or with a few, widely separated narrow teeth or short lobes
Native Yam Daisy
Microseris scapigera)
4.Leaf margins with continuous deep lobes pointing strongly backward
Taraxacum officinale spp. agg.)
5.Leaves noticeably rough and hairy; flowers longer than the involucre (group of bracts surrounding the base of the flower-head)
Hypochoeris radicata)
5.Leaves without hairs or very slightly hairy; flowers about as long as the involucre
Smooth Cat’s-ear (Hypochoeris glabra)
6.Inner row of involucre bracts becoming rigid and incurved with maturity; flower-heads single on unbranched stems (inner flowers sometimes brown tipped)
Cretan Weed
Hedypnosis cretica)
6.Involucre bracts remaining flexible with maturity; flower-heads multiple or if single, on branched stems
7.Leaves, stems and involucre covered in prickly or hooked hairs
7.Leaves with a smooth, hairless surface but sometimes with spiny midribs
8.Plant hairs short stiff and prickly which often arise from small white tubercles, fruit with an abruptly narrow, thin beak at the apex
Helminthotheca echioides)
8.Plant hairs simple or hooked without a prominent basal tubercle, fruit gradually tapering into the beak
Native Picris (Picris angustifolia)
9.Leaves with no or few lobes and without sharp teeth; flower-heads without stalks
Willow-leaf Lettuce
Lactuca saligna)
9.Leaves with sharp toothed or prickly lobes; flower heads with stalks
10.Leaves thin and rather limp or fleshy but not stiff, lobes without prickles but with irregular, pointed teeth
10.Leaves rather thick and stiff with stiff prickles or bristles on the margins
11. Plants with a creeping rhizomatous root system, outer bracts of involucre with a row of fleshy spines near the base
Dune Thistle
Actites megalocarpa)
11.Plants tap-rooted, outer bracts of involucre without spines
12. Involucre of ovate bracts with broad scarious (dry and papery) margins; flower-heads solitary on long stems and about 25 mm diameter (often with brownish centres)
False Sow-thistle
Reichardia tingitana)
12.Involucre of narrow bracts without scarious margins; flower-heads in leafy panicles and less than 25 mm diameter
13.Leaves with its terminal lobe much larger than the other lobes which are not constricted at the base
Common Sow-thistle
(Sonchus oleraceus)
13.Leaves with the terminal lobe similar in size to other lobes which are strongly constricted at the base
Clammy Sow Thistle
Sonchus tenerrimus)
14.Leaves bluish-grey, often with prickles along the underside of the mid-rib; leaf bases often twisted away from the horizontal to the vertical
Prickly Lettuce
Lactuca serriola)
14.Leaves bright green, generally smooth along the underside of the mid-rib; leaf bases with broad collars that bend down strongly against the stem
15.Leaf margins spiny, basal leaves deeply lobed, fruit 2-3 mm long
Rough Sow-thistle
(Sonchus asper)
15.Leaf margins sharply toothed, basal leaves wavy to moderately lobed, fruit 3-4 mm long
Native Sow-thistle
Sonchus hydrophilus)
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