Oxalis L.

Tutin, T. G., Heywood, V. H., Burges, N. A., Moore, D. M., Valentine, D. H., Walters, S. M. & Webb, D. A., 1981, Flora Europaea. Volume 2. Rosaceae to Umbelliferae, Cambridge University Press : 192

1. Oxalis L. 2

Perennial herbs, sometimes bulbous. Leaves palmately 3(-8)- foliolate, with or without stipules; leaflets usually indented at the apex, otherwise entire, showing sleep-movements. Inflorescence axillary, cymose, sometimes a cymose umbel or a single flower. Flowers often heterostylous. Sepals 5, free; petals 5, free or weakly united. Stamens 10, obdiplostemonous. Ovules numerous. Styles 5, free. Fruit a loculicidal capsule. Seeds projectile, with an elastic integument.

Several bulbous species, originally introduced by gardeners, have become established to the extent of being serious weeds; these species often develop tuberous roots. They multiply vegetatively by fragmentation into bulbils, but are virtually seed-sterile. The resultant propagation of various clones has obscured the taxonomy of the genus, which is in need of revision.

Literature: A. Chevalier, Rev. Bot. Appi. 20: 651-694 (1940). R. Knuth in Engler, Pflanzenreich (IV, 130): 1-481 (1930). D. P. Young, Watsonia 4: 51-69 (1958).

1 Petals yellow 2 Aerial stem absent; bulbils present at base of plant

10. pes-caprae 2 Aerial stem present; bulbils absent 3 Stem rooting at nodes; leaves alternate; stipules auriculate 4 Leaflets 5-18 x 8-23 mm; capsule 10-25 mm 1. comiculata 4 Leaflets 3-5 x 3-6 mm; capsule 5-7 mm 2. exilis 3 Stem not rooting at nodes; leaves mostly subopposite;

stipules not auriculate 5 Inflorescence umbellate; fruiting pedicels deflexed; stipules

oblong; stem with non-septate hairs 3. stricta 5 Inflorescence not umbellate; fruiting pedicels not deflexed;

stipules absent; stem with septate hairs 4. europaea 1 Petals white, red, violet or purple 6 Stem rhizomatous; bulb absent (although rhizome may be

swollen) 7 Rhizome 1-2 cm thick at apex; inflorescence corymbose

5. articulata 7 Rhizome less than 1 cm thick; flowers solitary 6. acetosella 6 Stem erect or absent; bulb present 8 Aerial stem erect, leafy; petals pale lilac 12. incarnata 8 Aerial stem absent; petals pink, red or violet 9 Leaflets not emarginate; petals 25-35 mm 11. purpurea 9 Leaflets emarginate; petals 15-20 mm 10 Leaves 4-foliolate 9. tetraphylla 10 Leaves 3-foliolate

11 Leaflets widest at or below middle, pubescent, and punc­

tate beneath near the margin 7. corymbosa

11 Leaflets widest near apex, subglabrous, not punctate

8. latifolia