1	"Leaves pinnately trifoliolate (terminal leaflet on an extension of the rachis); weed of tropical areas (Christmas Island) (subgen. Thamnoxys)"	"Oxalis barrelieri"
1	"Leaves palmately trifoliolate; plants widespread (subgen. Oxalis)"	2
2	"Aerial stem and branches absent or much reduced; leaves and peduncles radical or appearing so"	3
2	"Aerial stem and branches present, erect, ascending or creeping; leaves axillary, often whorled; peduncles axillary"	22
3	"Petals yellow or pale orange-fawn (red-veined in Oxalis obtusa)"	4
3	"Petals pale mauve, reddish, pink, purple, or white"	9
4	"Annual herb; petals 2.5–4 mm long; capsules readily produced in Australia"	"Oxalis micrantha"
4	"Perennial herbs (bulb and bulbils present); petals 10–25 mm long; capsules not produced in Australia"	5
5	"Inflorescences (13–)30-flowered; rhizome white and fleshy"	6
5	"Inflorescences 1-flowered; rhizome brown and papery"	7
6	"Petioles cylindric in cross-section, without wings"	"Oxalis pes-caprae"
6	"Petioles dorso-ventrally compressed and narrowly-winged"	"Oxalis compressa"
7	"Leaves 4–7-foliolate; leaflets narrow-elliptic to linear, often conduplicate"	"Oxalis flava"
7	"Leaflets 3 (4-foliolate in O. tetraphylla with purplish bases); leaflets broad, never narrow, not conduplicate"	8
8	"Bulb usually fusiform, deeply pitted and irregularly angled, tunics tough, reddish- to blackish-brown; petals pale yellow or pale orange-fawn with fine dark red veins, greenish at the base"	"Oxalis obtusa"
8	"Bulb usually globose, fibrous; petals bright yellow with reddish lines"	"Oxalis perdicaria"
9	"Leaflets mostly 4 (but juvenile plants often with 3 leaflets), often showing a purple band on upper surface (about proximal half)"	"Oxalis tetraphylla"
9	"Leaflets 3, purple band absent"	10
10	"Inflorescence 1-flowered"	11
10	"Inflorescence 3–30-flowered (if ever 1-flowered, then plants with bulb and or bulbils present)"	13
11	"Bulb and bulbils absent; petals 6–12 mm long, white; ovary glabrous; capsules ovoid to globose;  native herb of moist montane to alpine habitats"	"Oxalis magellanica"
11	"Bulb and bulbils present; petals 10–45 mm long, white or deep magenta; ovary pubescent on the upper half; capsules not formed in Australia"	12
12	"Leaflets hollow-dotted on both surfaces when dry; sepals with 2–4 apical calli"	"Oxalis depressa"
12	"Leaflets not hollow-dotted; sepals without calli"	"Oxalis purpurea"
13	"Leaflets with calli as dots at least around distal margins, usually evenly over surface (in Australia) or in a band along margins at base of notch or in the upper half of the lamina"	14
13	"Leaflets without calli"	16
14	"Rhizome short, robust, woody, often somewhat nodulose; bulbs absent"	"Oxalis articulata"
14	"Rhizome absent or if ever present then slender, non-woody; bulbs present"	15
15	"Abaxial surface of leaflets with calli usually evenly distributed over the surface (in Australia) or around distal margins only; abaxial surface of leaflets sparsely pubescent, margins ciliate"	"Oxalis debilis"
15	"Abaxial surface of leaflets with an orange callus on either side of the lobe at base of notch; abaxial surface of leaflets glabrous except for a few sparse hairs on the midrib of the lower surface"	"Oxalis violacea"
16	"Plant producing many small bulbils"	17
16	"Plant producing many small bulbils"	19
17	"Bulbils sessile on old bulbs"	"Oxalis vallicola"
17	"Bulbils produced from old bulbs on stolons"	18
18	"Leaflets obcordate, narrowly notched, apices of lobes usually less than 12 mm apart; inflorescences 1–2(–3)-flowered"	"Oxalis brasiliensis"
18	"Leaflets c. deltoid, widely incised to form divergent lobes ('fishtail-shaped') with apices 12–75 mm apart; inflorescences 6–14-flowered"	"Oxalis latifolia"
19	"Bulbs several in a cluster; abaxial surface of leaflets with glandular-pilose"	"Oxalis bowiei"
19	"Bulb single; abaxial surface of leaflets glabrous or variously hairy, never with glandular hairs"	20
20	"Leaflets broad obdeltate"	"Oxalis caprina"
20	"Leaflets linear"	21
21	"Leaflets 5-foliate (Australian plants) (sometimes the shorter outer leaves are 3-foliolate); leaflets not emarginate or only minutely emarginate; petals rose-pink"	"Oxalis polyphylla"
21	"Leaflets 3-foliolate; leaflets emarginate; petals white with prominent red-purple margin (appearing striped in convolute bud), very rarely rose-pink"	"Oxalis versicolor"
22	"Petals 14–30 mm long (occasionally < 14 mm long in O. incarnata), usually mauve, pink or purplish, yellow or green at base; bulbs (and sometimes bulbils) present; calli usually present on leaflets, bracts and sepals"	23
22	"Petals to c. 13 mm long, white or yellow; bulbs and bulbils absent; calli absent"	28
23	"Leaflets obcordate, bilobed with lobes 5–20 mm wide; bulbils formed on rhizome and in leaf axils; petals very pale lilac or pale pinkish-purple, greenish at base"	"Oxalis incarnata"
23	"Leaflets linear, oblong or cuneate, lobes 0.5–5 mm wide; bulbils when present formed on old bulb or rhizome; petals bright pink or purplish, yellow at base or white with prominent red-purple margin (appearing striped in convolute bud), very rarely rose-pink"	24
24	"Petals glandular-hairy on the outer surface; petals white with prominent red-purple margin (appearing striped in convolute bud), very rarely rose-pink"	"Oxalis versicolor"
24	"Petals glabrous or if hairy then the hairs eglandular; petals pink to purple"	25
25	"Leaflets 5-foliate (Australian plants) (sometimes the shorter outer leaves are 3-foliolate), leaflets not emarginate or only minutely emarginate"	"Oxalis polyphylla"
25	"Leaflets 3-foliolate, clearly emarginate or deeply bifurcate"	26
26	"Leaves arranged along the length of the stem; petioles (0.5–) 1–2 mm (–5) mm long; leaflets 3–5 (–7) mm wide"	"Oxalis hirta"
26	"Leaves clustered near the stem apex; petioles 4–40 mm long; leaflets 1.3–3 mm wide"	27
27	"Leaflets emarginate, often conduplicate; bracts alternate, situated near or imbricating the calyx; petals glabrous on the outer surface; stems 0.4–0.8 mm wide"	"Oxalis glabra"
27	"Leaflets bifurcate to the middle or beyond; bracts opposite, situated at the articulation above the middle; petals pubescent on the outer surface; stems 1.5–2 mm wide"	"Oxalis bifurca"
28	"Annual herb; petals only slightly longer than calyx; capsules 3–5 mm long; seeds more or less spherical, with apiculate ends"	"Oxalis micrantha"
28	"Perennial herbs (or annual in some forms of O. corniculata); petals usually much longer than calyx; capsules > 5 mm long or if shorter then petals white; seeds flattened"	29
29	"Hairs on stem and branches mostly antrorse (sometimes stems virtually glabrous in O. exilis); stipules conspicuous, not truncate (or sometimes truncate in O. exilis)"	30
29	"Hairs on stem and branches mostly spreading and/or retrorse; stipules either inconspicuous, or membranous and truncate"	35
30	"Seeds almost smooth to shallowly and transversely ridged; fruits with at least some patent septate hairs present"	"Oxalis thompsoniae"
30	"Seeds strongly transversely ridged; fruit without patent septate hairs (or if sometimes present as in O. exilis and O. rubens, then stems either usually rooting at nodes, or fruit to 24 mm long and 3–4 mm wide)"	31
31	"Seed ridges with distinctive white blotches and stripes; stems glabrescent"	32
31	"Seed ridges uniformly coloured; stems glabrescent to densely hairy"	33
32	"At least most inflorescences (2–)3–6-flowered, often umbel-like; fruits 10–13 mm long; plants not or only proximally rooting at nodes; stipules ca. 2 mm long; stems 1–1.3 mm wide"	"Oxalis corniculata"
32	"Inflorescence 1(–2)-flowered; fruits < 10.5 mm long;  plants usually readily rooting at most nodes; stipules 1–1.2 long; stems 0.5–0.7 mm wide"	"Oxalis exilis"
33	"Seeds with U-shaped grooves and rounded to subtruncate ridges (in cross-section); stem and branches glabrous to sparsely hairy; leaflets rather glaucous; stems, branches and petioles often at least partly reddish; fruit 13–24 mm long, often thick in middle; plants mostly of coastal dunes"	"Oxalis rubens"
33	"Seeds with V-shaped grooves and obtuse ridges (in cross-section) or ridges few and inconspicuous; stem and branches sparsely to densely hairy; stem, branches and leaves green to blue-green; fruit short and broad, or if longer (to 16 mm) then straight-sided; habitat various, but not known from coastal dunes"	34
34	"Fruit short and broad, 5–6.5 (–10) mm long, 2–3 mm diam., with simple hairs, occasionally with some patent septate hairs; apex tapering; inflorescence 1(–2)-flowered; stems creeping or ascending, often rooting at nodes"	"Oxalis exilis"
34	"Fruit moderately long, 8–30 mm long, 2.5–5 mm diam., septate hairs absent; apex abruptly narrowed; inflorescence (1–)2–3(–6)-flowered; stems ascending to erect, occasionally creeping, rarely rooting at nodes"	"Oxalis perennans"
35	"Flower solitary, white; fruit ovoid to globular, 4–5 mm long, glabrous; wet montane or subalpine forests and heathlands"	"Oxalis magellanica"
35	"Flowers 1–6, yellow; fruit subglobose to cylindric, more than 6 mm long, retrorse- hairy"	36
36	"Fruit relatively short and stout, usually 7–9 mm long, c. 3 mm diam.; branches long and trailing; leaflets usually densely hairy"	"Oxalis chnoodes"
36	"Fruit long and relatively narrow, usually 7–20 mm long, 1.5–3 mm diam.; branches erect or trailing; leaflets densely hairy or glabrescent"	37
37	"Stipules obvious, 2–3 mm long, truncate; taproot, if present (rarely), not stout and woody"	"Oxalis corniculata"
37	"Stipules inconspicous, to 1 mm long, keeled; taproot stout and woody"	"Oxalis radicosa"