Oxalis corniculata L.
horned oxalis
Perennial with slender primary root. Stems prostrate to suberect, to c. 40 cm long, slender, weak, branched, often rooting at nodes, covered with spreading flexible hairs. Lvs 3-foliolate, alternate, sometimes appearing almost whorled on short lateral stems, green or purple. Petiole (0.5)-1-7 cm long, with spreading flexible hairs; stipules usually 2-3 mm long, broad, with free, truncate apex, nearly glabrous to densely covered in long hairs. Petiolules very short. Lamina of leaflets equal, (2.5)-5-18 × (3)-7-23 mm, broadly obcordate, glabrous or sparsely hairy, with densely hairy midrib below; sinus of lamina narrow or broad, extending 1/2 length of lamina; margin ciliate; calli 0; lobes 2, usually rounded, occasionally leaflets not lobed. Infl. 1-5-flowered; peduncle 1-4 cm long, to 9.5 cm long at fruiting, with antrorse hairs; pedicels < peduncles, with antrorse hairs. Bracts 2-3.2 mm long, linear-subulate or linear-lanceolate, nearly glabrous, or hairy at base of pedicels; calli 0. Sepals 3-4.5-(5.2) mm long, elliptic-lanceolate, elliptic-ovate to elliptic-obovate, with antrorse hairs; margins sometimes red; calli 0. Petals 4.5-10-(13) mm long, oblong-obovate, yellow, glabrous. Stamens at 2 levels; filaments glabrous, connate towards base. Styles <, =, or a little > longer stamens, densely hairy. Capsule (6)-10-18-(20) mm long excluding styles, cylindric, usually densely clothed in short, simple, eglandular, ± retrorse hairs, or sometimes hairs sparser and then also with scattered, long, wide, curly, septate hairs, occasionally glabrous. Seed 1-1.3-(1.7) cm long, broad-ellipsoid, dark purplish brown; transverse ridges 4-10, either subacute with deep grooves between and sometimes white-topped, or obtuse with shallow grooves.
N.; S.: widespread and often common throughout; K.
Almost cosmopolitan 1944
Mostly in and around settlements, waste places, roadsides, plantations and gardens, cultivated ground.
FL Jan-Dec.
Possibly poisonous (Connor 1977).
All the plants of this sp. in N.Z. belong to subsp. corniculata. This subsp. has often been confused with the indigenous O. exilis and O. rubens.
It seems most likely that none of the 3 vars of subsp. corniculata in N.Z. are indigenous. The description in Allan (1961) of O. corniculata is probably based on 3 main spp. of sect. Corniculatae DC. : O. corniculata, O. exilis, and O. rubens, because var. ciliifera (Cunn.) Hook.f. and var. microphylla Hook. f. are referable to O. exilis whilst var. crassifolia (Cunn.) Hook. f. is a synonym of O. rubens. Other names mentioned by Allan in a footnote under O. corniculata should also be treated as synonyms of O. exilis and O. rubens. The names O. corniculata var. repens and O. repens are sometimes used in N.Z. for subsp. corniculata.
Lourteig, A., Phytologia 42(2): 57-198 (1979), cited N.Z. specimens for 2 vars of subsp. corniculata and others simply under subsp. corniculata. Her conclusion that the distinction between one of these vars and typical var. corniculata can be blurred in the Pacific region, is supported by examination of many N.Z. specimens.
The taxa are:
(1) * var. atropurpurea Planchon. Lvs ± purple above and below, glabrous above; peduncle and calyx purple; capsule hairs rather dense and ± touching, eglandular; seed c. 1.5 mm long, usually with 9-11, acute ridges.
(2) * var. corniculata. Lvs green above and below, glabrous or nearly so above; capsule hairs dense and touching, eglandular; seeds 1-1.3 mm long, usually with 8-11, deep, ± acute ridges.
(3) * var. villosa (M. Bieb.) Hohen. Lvs green above and below, ± glabrate above; capsule hairs not or scarcely touching, short or long and simple, and long, flattened, and glandular; seeds 1.3-1.7 mm long, usually with 4-6, low, obtuse ridges.
These infraspecific taxa of O. corniculata are of doubtful status because there is considerable overlap in characters. Var. atropurpurea may well be only a purple variant. Var. villosa is said by Lourteig to be atypical in the Pacific, and indeed the status of plants referred to var. villosa in N.Z. is unclear; they probably do not represent var. villosa sens. strict. from the Caucasus region. The plants differ significantly from typical O. corniculata in that they have somewhat larger stipules, shorter and more broadly cylindric capsules with a different type and frequency of hairs, and shallower and fewer seed ridges. Plants with these characters seem to be infrequent and scattered throughout lowland parts of the North Id, northern South Id, Christchurch, and the Kermadec Is. Undoubtedly, they have often gone unrecognised and thus may be commoner than the above distribution indicates. Such plants are also found in Australia (J. Thompson, pers. comm.).
In N.Z. the habitats of the 3 vars are similar except that var. atropurpurea is mostly a garden weed.
The related O. fontana Bunge, another and more distinct sp. in sect. Corniculatae, has been recorded wild for N.Z., see under key.
