Jonsell, B. 2001: Flora Nordica 2Stace, C. 2019: New flora of the British Isles, ed. 4
This new key is based on the cited floras. It needs further testing as regards Cypriot material. Various details have been supplemented.
1Plant stinking of rotting fish when fresh, usually procumbent to ascending, strongly farinose; leaf-margin sometimes angled at the widest point but otherwise entire
1'Plant not stinking when fresh, usually ascending to erect, farinose or not; leaf-margin usually toothed or lobed, if entire, then leaf-blades very narrow
2Edge of seed distinctly keeled; pericarp firmly adherent to seed; tepals with a conspicuous keel near apex; leaf-margin distinctly serrate
2'Edge of seed convex or indistinctly keeled; pericarp free or adherent to seed; tepals with a rounded back or keeled along most of their length; leaf-margin entire to dentate or serrate
3Inflorescences not or very sparsely farinose
3'Inflorescences farinose, especially when young
4All flowers with 5 tepals; horizontal seeds with black testa; inflorescence with strictly erect branches
4'Terminal flowers with 5, lateral flowers with 3 tepals; horizontal seeds with brown or redbrown testa; inflorescence not with strictly erect branches
5Leaf-blades about as long as wide, distinctly 3-lobed
5'Leaf-blades clearly longer than wide, entire to slightly 3-lobed, if wider than long then plant with purple vesicular hairs
6Seeds broadly ovate, 1-1.2 mm diam.; blades of lower leaves often narrowly oblong to elliptic, i.e. with parallel sides or trullate, with entire to regularly dentate margin
6'Seeds suborbicular, (1-)1.2-1.5 mm diam.; blades of lower leaves various but not oblong to elliptic; margin entire to irregularly serrate, teeth sometimes lobe-like
7Leaf-blades up to 2.5(-3.5) cm long, more than twice as long as wide; those of lower leaves trullate, fairly acute; plant more or less as high as wide, with long, procument, basal branches, typical tumbleweed habit
7'Leaf-blades usually at least 3 cm long, about twice as long as wide, elliptic to oblong, obtuse; plant usually higher than wide, with pyramidal growth
8Usually (10-)30-70(-150) cm high; plant without purple vesicular hairs; leaf-blades up to 8 x 3.5 cm
8'Often up to 200 cm high; young parts of the plant usually covered with purple vesicular hairs or plant at least tinged with red
9Always with at least some leaves longer than 6 cm, often leaves up to 14 cm long, not coriaceous; shoots extensively reddish-purple; basal leaves irregularly toothed but scarcely lobed
9'Leaves usually less than 6 cm long, sometimes leaves up to 14 cm long, somewhat coriaceous; plant tinged with red; lower leaves with distinct basal lobe on each side