Guide to non-yellow flowering Oxalis in Australia
Oxalis is a large cosmopolitan genus (currently 566 accepted species in Plants of the World Online) of mostly small herbs. It's represented in Australia by 32 recorded species, most of which (24) are non-native:
Native:
Oxalis chnoodes
Oxalis exilis
Oxalis magellanica
Oxalis perennans
Oxalis radicosa
Oxalis rubens
Oxalis sp. Pilbara (M.E. Trudgen 12725)
Oxalis thompsoniae
Non-native:
Oxalis articulata
Oxalis barrelieri
Oxalis bifurca
Oxalis bowiei
Oxalis brasiliensis
Oxalis caprina
Oxalis compressa
Oxalis corniculata
Oxalis debilis
Oxalis depressa
Oxalis dillenii
Oxalis flava
Oxalis glabra
Oxalis hirta
Oxalis incarnata
Oxalis latifolia
Oxalis laxa
Oxalis micrantha
Oxalis obtusa
Oxalis perdicaria
Oxalis pes-caprae
Oxalis polyphylla
Oxalis purpurea
Oxalis violacea
(note there is also another entity, Oxalis vallicola, which is treated as separate/valid by VicFlora, but synonymised under O. latifolia everywhere else. It is separated from latifolia in the VicFlora key as: bulbils produced from old bulbs on stolons = latifolia, bulbils sessile on old bulbs = vallicola)
Many of these species, including 7 of the 8 natives, look very similar: yellow flowers and relatively small leaflets. It can often be tricky to differentiate these species, especially from photos which often lack important diagnostic characters such as hair types, stipules or fruits/seeds (which are often not present). For the most part, however, the other species, which include pink, purple, orange and white flowers, are relatively easy to identify. This photographic guide should make it easy to identify these species when they're in flower, although I also point out other useful traits too relating to leaves and below ground structures (if relevant). There are of course many other relevant characters, but I have tried to keep each entry relatively simple; more extensive descriptions for each species can be accessed in online floras. I have mostly used photos from Australian observations, except for a few species which are yet to be observed in Australia on iNaturalist, or species for which the few photos I needed were under all rights reserved copyright licenses.
Note that this guide is most useful when observing flowering specimens. For some of the species treated here, however, the leaves are highly distinct and are the most obvious diagnostic character once you have established the genus as Oxalis. Overall, as for any plant group, taking into consideration the combination of all characters for any given species will provide the most accurate identifications.
Native species
Oxalis magellanica
Distribution in Australia: Victoria (rare, Otway Range, Central Highlands between Lake Mountain and Baw Baw Plateau, and Errinundra Plateau only), Tasmania. Also New Zealand and South America.
Flowers: petals white, pale green throat (A).
Leaves: leaflets love heart-shaped with a distinct notch at the apex. Noticeable 'fold' down the centre dividing each leaflet into two lobes, Leaflets usually very small, barely exceeding 10 mm maximum length (usually smaller) (B).
General: a small species, usually up to ~10 cm max height (C). Very distinct, difficult to confuse with anything else.
A and C - @annabelc; B - @sheriff_woody_pct
Non-native species
Oxalis articulata
Distribution in Australia: broadly distributed across southeastern Australia from Brisbane to Adelaide, including Tasmania. As far inland as around Temora in NSW, plus a few rare records along the Vic/NSW border.
Flowers: petals usually broadly rectangular- or wedge-shaped (helps to differentiate from some of the other pink-flowering Oxalis, which have round petals), pale pink through to a rich pink-purple with distinct dark striations extending upwards from the throat. Almost always with a distinct dark-purple flush encircling the throat
Leaves: leaflets love heart-shaped with a distinct notch at the apex.
General: This species is very similar to Oxalis brasiliensis. Compared to O. brasiliensis, O. articulata:
- petals seems to more consistently be more elongate rectangular (A), compared to brasiliensis which often seems to have squatter, more wedge-shaped petals (although both petal types are present in both species)
- leaflets seem to more consistently be a little longer than wide or roughly as long as wide (B), compared to brasiliensis where the leaflets seem to more consistently be a little wider than they are long.
- the notches at the leaflet apices are typically deeper/more prominent in O. articulata.
- has a woody rhizome (C) instead of bulbs + bulbils.
A and C - @nomennudum; B - @silversea_starsong
Oxalis barrelieri (no Australian iNaturalist observations at time of writing)
Distribution in Australia: Christmas Island.
Flowers: petals small, white or sometimes pale pink-purple, throat rich yellow (A).
Leaves: leaflets oval-shaped, central leaflet larger than the others (B).
General: usually erect growth habit, can reach up to 1.5 m tall (C). Highly unmistakeable and unlike any other Oxalis in Australia.
A - @deniszabin ; B - @pseudoshuigeeee ; C - @takashi_nishiki
Oxalis bifurca (no Australian iNaturalist observations at time of writing)
Distribution in Australia: Victoria (although probably now extinct, only known from three 1925 records in Little River Railway Reserve between Melbourne and Geelong), NSW (records only from Campbelltown) and South Australia (also possibly extinct, four records all from the 1960s, near Adelaide and Gawler).
Flowers: petal colour variable, including stark white (A), very pale pink, hot pink or (rarely) coral, throat yellow-green.
Leaves: each leaflet divided into two distinct, (usually) narrow lobes.
General: another unmistakeable species in comparison to other Australian Oxalis given its distinct leaves.
A - @lucstrydom; B - @jkrenz; C - @tonyrebelo; D - @mr_fab
Oxalis bowiei
Distribution in Australia: broadly distributed across southern Australia, including southern WA, South Australia, Victoria, and NSW, plus a few rare records in SE Queensland.
Flowers: petals usually quite rounded and broad, overlapping, usually very rich/hot pink, sometimes paler, yellow-green throat (A).
Leaves: leaflets large (up to ~45 mm long), very rounded, shallow notch at apex (B).
General: This species is somewhat similar to Oxalis purpurea. Compared to O. purpurea, O. bowiei:
- has many flowers per peduncle, compared to purpurea which only has one
- usually has a much less prominent throat, compared to purpurea which typically has a very prominent, rich yellow throat
- leaflets are weakly, yet nonetheless still noticeably, notched at the apex, compared to the usually unnotched and more circular leaflets of purpurea. Also, purpurea leaflets tend to be crowded to one side (whereas bowiei leaflets are arranged largely equidistant from each other on the petiole)
- greenish-yellow petal bases obvious in closed flowers, compared to the usually much stronger/richer yellow petal bases present in purpurea.
Oxalis brasiliensis
Distribution in Australia: similar distribution to O. articulata, spanning from the NSW border around southeastern Australia to Adelaide, but excluding Tasmania, and seemingly more restricted to major cities/large urban areas (although this may be due to sampling bias).
Flowers: petals usually broadly rectangular- or wedge-shaped (helps to differentiate from some of the other pink-flowering Oxalis, which have round petals), pale pink through to a rich pink-purple with distinct dark striations extending upwards from the throat. Almost always with a distinct dark-purple flush encircling the throat.
Leaves: leaflets usually squashed/flattened love heart-shaped with a typically quite shallow notch at the apex.
General: This species is very similar to Oxalis articulata. Compared to O. articulata, O. brasiliensis:
- petals seems to more consistently be squatter and more wedge-shaped (A), compared to articulata which often seems to have more elongate rectangular petals (although both petal types are present in both species)
- leaflets seem to more consistently be a little wider than they are long (B), compared to articulata where the leaflets seem to more consistently be a little longer than wide or roughly as long as wide.
- the notches at the leaflet apices are typically shallower in O. brasiliensis
- has bulbs + bulbils (C) instead of a woody rhizome.
A and C - @nomennudum; B - @garry34
Oxalis caprina
Distribution in Australia: WA (restricted to around Perth southwards to Bunbury), South Australia (Adelaide and a few old Kangaroo Island records) and Victoria (a single recent iNaturalist record near Truganina)
Flowers: petals usually very pale mauve or lilac, sometimes white or with faint blue-ish tinge, prominent yellow throat (A), petals with prominent yellow petal bases obvious in closed flowers (B).
Leaves: leaflets love heart-shaped, very prominently/strongly notched at the apex (C).
General: The strongly notched leaflets are quite distinct among the non-yellow flowering species, similar to those of Oxalis pes-caprae (a yellow flowering species)
A - @jamie2014; B - @plantrant; C - @willeminalunae
Oxalis debilis
Distribution in Australia: every state and territory in Australia, as well as Lord Howe Island and Norfolk Island, although most records are concentrated along the east coast from Brisbane to Sydney.
Flowers: pale to rich pink (usually towards the rich end) with distinct dark striations extending upwards from the throat, usually prominent bright green throat (A).
Leaves: leaflets love-heart shaped, usually very fat and rounded, often with quite distinct wrinkle-like veins, notched at the apex (B). Leaves consistently large and towards the maximum end of their size range (leaflets 40-45 mm long)
General: Similar to flowers of O. articulata and O. brasiliensis, but O. debilis lacks the distinct dark-purple flush encircling the throat, and the throat of O. debilis flowers is usually a much more obvious bright green compared to the subtler and less extensive yellow-green throat of the other two.
A - @russellcumming; B - @vickymills
Oxalis depressa
Distribution in Australia: WA (two 1990s records from Busselton, plus what seems to be a small population at Bunbury recorded on iNaturalist)
Flowers: petals white (both WA specimens were noted to have white flowers), pale pink or hot pink (A). Throat rich yellow, petals with prominent yellow petal bases obvious in closed flowers.
Leaves: leaflets usually very rounded, rarely notched at the apex. Leaves usually noticeably asymmetrical, with the leaflets crowded towards one side. Leaves usually with conspicuously 'pebbly' looking surface (large epidermal cells) (B).
General: This species is very similar to Oxalis purpurea. Compared to O. purpurea, O. depressa:
- has leaflets with a conspicuous 'pebbly' looking surface due to the large cells, whereas purpurea lacks these
- is largely glabrous, whereas purpurea tends to be pubescent on the stems and often on the leaflet margins
- has petals that seem to overlap less often than compared to purpurea, although this isn't the most reliable/consistent character.
A - @deans_beaver; B - @carinalochner
Oxalis flava
Distribution in Australia: WA (souhwest, mostly east of Perth), South Australia (Adelaide and surrounding region), and NSW (very rare, some 1950s records from Albury and an 1897 record from Sydney).
Flowers: petals for this species are usually yellow (sometimes with purple-brown edging, obvious in closed flowers (A)), but I have included it here as it also has a not uncommon white flowering form (and a seemingly rarer pink-purple form). For white-petalled specimens, the throat is prominent yellow (B).
Leaves: each leaf with 4-7 leaflets, leaflets usually slender, often folded lengthways and with hooked tips (C). These leaflets can be variable in shape, and are sometimes unfolded (D), but the large number of them (4-7) is a distinct feature compared to the other Oxalis here)
General: the leaves make this species unmistakeable.
A - @ydnewp2; B - @knysna_wildflowers; C - @darcywhittaker; D - @manfdot
Oxalis glabra
Distribution in Australia: WA (stretching along the eastern coast from around Jurien Bay all the way down to the south coast, although concentrated around Perth, plus a single iNaturalist record from between Ravensthorpe and Esperance), South Australia (around Adelaide) and Victoria (rare, near Melbourne and northwards).
Flowers: petals usually quite blocky/squarish, hot pink, prominent yellow throat (A), petals with prominent yellow petal bases obvious in closed flowers (B).
Leaves: leaflets small, usually elongate, slender, often weakly to moderately folded lengthways and weakly notched at the apex (C).
General: This species is quite similar to Oxalis hirta. Compared to O. hirta, O. glabra:
- has glabrous petals, whereas in hirta the exterior of the petals are hairy
- tends to have more glabrous leaves (but still often finely hairy), whereas hirta tends to be more pubescent
- has petioles as long or longer than the leaves (petioles up to 22 mm long), whereas hirta has petioles much shorter than the leaves (petioles usually just 1-2 mm long)
- has leaflets without glands on the lower surface, but with blister-like epidermal cells, whereas hirta has the opposite (many glands, no blister-like cells).
- has leaflets that tend to be narrower (usually 1-2 mm wide), whereas hirta often has broader leaflets (up to 7 mm wide).
- has mostly petiolate leaves that are mostly crowded towards the top of the stem, whereas hirta has almost sessile leaves distributed along most of the stem.
A and C - @russellcumming; B - @slaadi
Oxalis hirta
Distribution in Australia: WA (rare, very few scattered records in southwestern corner), South Australia (mostly greater Adelaide area and surrounds, one 1965 record from the Eyre Peninsula) and Victoria (mostly greater Melbourne area).
Flowers: petals usually quite blocky/squarish, hot pink (although there are also white and pale purple flowering forms), prominent yellow throat (A), petals with prominent yellow petal bases obvious in closed flowers, hairy on outside (B).
Leaves: leaflets small, usually elongate, slender, often weakly to moderately folded lengthways and weakly notched at the apex (C).
General: see comments above for comparison with Oxalis glabra
A - @insiderelic; B - @markberry; C - @alan_dandie
Oxalis incarnata
Distribution in Australia: broadly distributed across southern Australia, including WA (southwestern corner), South Australia (mostly greater Adelaide area), Victoria, NSW (Sydney southwards) and Tasmania.
Flowers: petals white or very very pale pink-purple (A), green throat, often prominent and with distinct striations extending upwards (B).
Leaves: leaflets love-heart shaped, moderately to strongly notched at the apex (C).
General: somewhat similar to Oxalis caprina, but O. incarnata has bigger flowers and an obvious green throat compared to the yellow throat of the former, plus incarnata also has a prominent stem (no aboveground stem in caprina) and only a single flower per peduncle (many per peduncle for caprina).
A - @light-up-gold; B - @bunts; C - @reiner
Oxalis latifolia
Distribution in Australia: broadly distributed across southeastern Australia from around Brisbane to Adelaide, including Tasmania, as well as scattered records near Townsville and Cairns, and a single recent iNaturalist record in Perth.
Flowers: petals pink-purple (rarely white), throat yellow with green striations (A). Each sepal with two conspicuous orange calli (calluses) at the apex (B).
Leaves: leaflets fish-tail shaped (C). Like Oxalis debilis, leaves are consistently large and towards the maximum end of their size range (leaflets 40-45 mm long)
General: largely unmistakeable given the size and shape of the leaflets.
A - @simon_hamlet; B and C - @thebeachcomber
Oxalis obtusa
Distribution in Australia: Victoria (mostly greater Melbourne, scattered records in Geelong and in regional Victoria near Bendigo, Beechworth and Seymour).
Flowers: petals very variable in colour, including very pale yellow (almost white), yellow, pink, and several shades of orange or orange-pink. Victorian plants tend to be pale yellow (A) or pink-orange. Throat rich, prominent yellow, surrounded by a rich orange ring. For most colour forms, the petals are covered in very prominent veins, visible on both surfaces (B).
Leaves: also variable, can be love-heart shaped or more linear/rectangular (C).
General: Although the leaves and flowers are both quite variable, the distinct petal venation usually makes this species quite obvious.
A - @spoonbilljames1995; B - @sequoia_l; C - @dhoare
Oxalis polyphylla (no Australian iNaturalist observations at time of writing)
Distribution in Australia: exceedingly rare (presumably as a garden escape for each record), with a single WA record (Mount Barker in the southwest), and two cemetery records (Canberra and Melbourne, possibly flowers placed on graves rather than naturalised plants). Also listed by APC as occurring in South Australia, but the ALA has zero collections or other records there.
Flowers: petals white, pale pink or pink purple, yellow throat (A).
Leaves: leaflets very elongate and slender (much longer than broad), often strongly folded lengthways (B), often clustered towards the top of the plant (C). Leaflet number variable, ranging from 3 to 8.
General: fairly distinct based on leaf morphology.
A - @renatakruyswijk; B - @knysna_wildflowers; C - @karooicus
Oxalis purpurea
Distribution in Australia: broad distribution across southern Australia spanning scattered records from as far north as K'gari, along the NSW coast, Victoria, Tasmania, South Australia and southwestern WA (with a few scattered records extending as far north as Geraldton).
Flowers: petals usually strongly overlapping, hot pink (sometimes paler pink) (A), with a white flowering morph also common (B). Throat rich yellow, petals with prominent yellow petal bases obvious in closed flowers.
Leaves: leaflets usually very rounded, rarely notched at the apex. Leaves usually noticeably asymmetrical, with the leaflets crowded towards one side (C).
General: the stems are often bright red (D). Oxalis depressa is a very similar species, see the entry for it above for a comparison.
A - @franksteenhuisen; B - @gillbsydney; C - @kezzza4; D - @thebeachcomber
Oxalis violacea (no Australian iNaturalist observations at time of writing)
Distribution in Australia: WA (scattered records along the coast from Albany to Perth).
Flowers: petals white, pink or pale purple, throat yellow-green with a distinct white/pale ring surrounding it (A).
Leaves: leaflets love-heart, squashed love-heart, or fish-tail shaped (like Oxalis latifolia), although usually smaller. Leaflets often with distinct purple bands on upper surface (not always present though) (B), and lower surface sometimes suffused with purple also.
General: similar to a number of other species when considering individual characters, but fairly recognisable looking at the combination of all of them.
A - @illinoisbotanizer; B - @smoyers24.
