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.
1Perianth becoming red and succulent in fruit; flowers in more or less sessile, axillary glomerules; leaf-blades more or less triangular, glabrous
1'Perianth not becoming red and succulent in fruit; flowers in lax cymes or in glomerules, but then usually not all axillary; leaf-blades rarely triangular, often farinous, especially when young
2Plant stinking of rotting fish when fresh, usually procumbent to ascending, strongly farinose; leaf-margin sometimes angled at the widest point but otherwise entire
2'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
3Edge of seed distinctly keeled; pericarp firmly adherent to seed; tepals with a conspicuous keel near apex; leaf-margin distinctly serrate
3'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
4Inflorescences not or very sparsely farinose
4'Inflorescences farinose, especially when young
5All flowers with 5 tepals; horizontal seeds with black testa; inflorescence with strictly erect branches
5'Terminal flowers with 5, lateral flowers with 3 tepals; horizontal seeds with brown or redbrown testa; inflorescence not with strictly erect branches
6Leaf-blades about as long as wide, distinctly 3-lobed
6'Leaf-blades clearly longer than wide, entire to slightly 3-lobed, if wider than long then plant with purple vesicular hairs
7Seeds 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
7'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
8Leaf-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
8'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
9Usually (10-)30-70(-150) cm high; plant without purple vesicular hairs; leaf-blades up to 8 x 3.5 cm
9'Often up to 200 cm high; young parts of the plant usually covered with purple vesicular hairs or plant at least tinged with red
10Always 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
10'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