Oxalis procumbens Steud. ex A. Rich.

Nile and Mediterranean regions, Oases, eastern desert (Along Suez Canal) and Sinai.

Cosmopolitan, especially warm regions.

This species is used medicinally.

This highly successful weedy species is so widespread, particularly in areas disturbed by humans, that its origin is unknown. It has been reported from China in additional provinces, such as Heilongjiang, Jilin, Ningxia, and Xinjiang, where it is likely a weed in protected locations, such as in greenhouses. The most frequently encountered variety in China is Oxalis corniculata var. villosa (M. Bieberstein) Hohenacker, but this variety is often under-recorded due to the glabrescent nature of the adaxial surface of the leaves. Oxalis corniculata var. villosa has leaflet blades covered with trichomes all over the abaxial surface, whereas for var. corniculata the abaxial surface has trichomes only on the midrib of the terminal leaflet and the basal half of the lateral leaflets. Plants with leaves, and to a lesser extent all vegetative parts, suffused purplish red are Oxalis corniculata var. atropurpurea Planchon. The purple coloration is conspicuous in plants from exposed sunny habitats but is much less prominent in shaded plants and fades on drying, making confident determination of old herbarium specimens difficult. Determination of the exact distribution of these varieties in China needs additional study.

Synonyms of Oxalis corniculata var. villosa include: Oxalis villosa M. Bieberstein, Fl. Taur.-Caucas. 1: 355. 1808; Acetosella corniculata var. villosa (M. Bieberstein) Kuntze; ?O. corniculata f. maritima Masamune; O. corniculata var. sericea Knuth; O. corniculata var. trichocaulon H. Léveillé; O. corniculata f. villosa (M. Bieberstein) Goiran; ?O. corniculata var. viscidula Wiegand; O. langloisii (Small) Fedde; O. thunbergiana Montrousier; Xanthoxalis langloisii Small. Synonyms of Oxalis corniculata var. atropurpurea include: Oxalis corniculata f. purpurea (Parlatore) Knuth; O. corniculata var. purpurea Parlatore; O. tropaeoloides Schlachter ex Planchon; Xanthoxalis corniculata f. atropurpurea (Planchon) Nakai; X. corniculata var. atropurpurea (Planchon) Moldenke; X. corniculata f. purpurea (Parlatore) Nakai.

A very variable species in form and size. Common during the spring season from the plains to 2700 m. The leaves can be used as vegetable. The juice of the plant mixed with onion is used to remove warts.

Plants creeping, pubescent, rooting at the nodes. Leaflets 4—15 mm long, 8—32 mm broad, obcordate, pilose-tomentose. Flowers solitary or in 2—5 flowered axillary umbels. Pedicel 5—15 mm long, deflexed in fruit. Bracts 3—5, linear. Sepals 5, linear lanceolate, pilose. Petals 5, yellow. Filaments glabrous. Carpels 5, pubescent; styles longer than the shorter stamens. Capsule 1—2.5 cm long, subcylindric, pubescent. Seeds 1.5 mm long, brown, transversely ribbed.

Annuals or short-lived perennials. Stems to 50 cm but often shorter, creeping, ascending to semierect, variably pubescent with adpressed simple hairs. Rootstock a slender taproot, sometimes woody; stems several, freely rooting at nodes in contact with soil; stolons absent. Stipules small, rectangular to auriculate. Leaves alternate or pseudoverticillate; petiole 1-8(-13) cm; leaflet blades obcordate, 0.3-1.8 × 0.4-2.3 cm, green or suffused purplish red, variably adaxially and abaxially pubescent, apex deeply emarginate. Inflorescences umbellate, (2-)1-5(-7)-flowered; peduncle usually slightly longer than petioles; bracts linear-lanceolate, 2-4 × ca. 1 mm. Pedicel 4-15(-20) mm, deflexed or horizontal in fruit, densely strigose. Sepals oblong-lanceolate, 3.5-5 × 1.2-2 mm, margin ciliate especially at apex. Petals bright yellow, oblong-obovate, 6-8 × 3-4 mm. Capsule long cylindric, 8-25 × 2-3 mm, 5-sided, strigose with abundant simple hairs and a few septate hairs on dehiscence sutures. Seeds brown to brownish red, 5-14 per locule, ovoid-oblong, 1-1.5 × 0.8-1 mm, transversely ridged. Fl. and fr. Feb-Oct. 2n = 24.

Anhui, Chongqing, Fujian, Gansu, Guangdong, Guangxi, Guizhou, Hainan, Hebei, Henan, Hubei, Hunan, Nei Mongol, Jiangsu, Jiangxi, Liaoning, E Qinghai, Shaanxi, Shandong, Shanxi, Sichuan, Taiwan, Xizang, Yunnan, Zhejiang [Bhutan, India, Japan, Korea, Malaysia, Myanmar, Nepal, Pakistan, Russia, Thailand; almost cosmopolitan].

Distribution: A cosmopolitan weed.

Almost cosmopolitan.

300-2900 m

Fl. Per. March December.

Mountain slopes, forests, grasslands, riversides, roadsides, fields, wastelands; sea level to 3400 m.

Acetosella corniculata (Linnaeus) Kuntze; Oxalis corniculata f. erecta Makino; O. corniculata subsp. repens (Thunberg) Masamune; O. corniculata var. repens (Thunberg) Zuccarini; O. corniculata subsp. subglabra (Kuntze) Masamune; O. corniculata var. taiwanensis Masamune; O. minima Steudel; O. procumbens Steudel; O. repens Thunberg; O. repens var. erecta (Makino) Masamune; O. repens f. speciosa Masamune; O. taiwanensis (Masamune) Masamune; Xanthoxalis corniculata (Linnaeus) Small; X. corniculata var. repens (Thunberg) Nakai; X. repens (Thunberg) Moldenke.

corniculata: with a small horn-like appendage

Annual herb, without bulbs. Stems procumbent or ascending, less often erect, often rooting at the nodes, with spreading hairs. Leaflets: lamina 3-15 × 5-20 mm, obcordate-cuneate, pubescent; apex deeply emarginate. Flowers yellow, in 1-6-flowered bracteate pseudumbels. Petals 8-10 mm. Capsule exserted, cylindric, ± 5-angled.

Common in suitable habitats

Zizeeria knysna (Sooty blue) Zizula hylax (Gaika blue)

Cosmopolitan weed

Xanthoxalis macrantha (Trel.) Small, Fl. SE. U. S. 667. 1903
Oralis corniculaia (?) macrantha Trel. Mem. Bost. Soc. Nat. Hist. 4: 88. 1888. Oxalis macrantha Small, Bull. Torrey Club 23: 268. 1896.
Stems erect or ultimately decumbent, 1-4 dm. tall, often rather conspicuously elongate, strigillose, commonly densely so on the lower part, especially when young ; leaflets deepor bright-green, the blades 7-14 mm. wide, glabrous or with scattered hairs on both sides and often ciliate ; peduncles mostly much longer than the petioles ; pedicels strigillose, refracted at maturity; sepals 5-6 mm. long; petals golden-yellow, 10-20 mm. long; longer filaments pubescent ; capsules columnar, stoutish, 10-14 mm. long, tomentulose, gradually narrowed into a long beak.
Type locality : Arkansas.
Distribution : Georgia to Arkansas, Florida, and Mississippi.

Xanthoxalis langloisii Small, Fl. SE. U. S. 667. 1903
Oxalis corniculata microphylla Oriseb. Fl. Brit. W. Ind. 133. 1859. Not O. microphylla Poir. 1816.
Plants similar to those of A', corniculata in habit, but usually smaller in all of their parts ; leaflets paleor light-green, the blades 3-10 mm. broad, somewhat ciliate and more or less pubescent on both surfaces ; peduncles about as long as the petioles or longer ; pedicels strigillose; sepals 2.5-4 mm. long; petals light-yellow, 5-8 mm. long; longer filaments pubescent; capsules columnar, 9-14 mm. long, minutely pubescent, rather gradually narrowed at the apex.
Type locality' : St. Martinsville, Louisiana.
Distribution : Tennessee to Florida and Texas, and in Cuba.

Xanthoxalis corniculata (L.) Small, Fl. SE. U. S. 667. 1903
•s corniculaia L,. Sp. PI. 435. 1753. 'Oxalis repens Tliunb. Oxal. 16. 1781. Ova/is Pilli in: Jacq. Oxalis Monogr. 28. 1794. ( ) i alis jamaicensis Macfad. Fl. Jam. 1 : 182. 1837. ? Oxalis herpestica Hchleclit. LJnnaea27: 525. 1856. Oxalis corniculata pubescens Griseb. Fl. Brit. W. Ind. 133. 1859.
Sterns branched at the base, the branches creeping, 0.5-4 dm. long, or more, loosely pubescent, the hairs often few and scattered; leaflets deep-green, the blades 5-12 mm. broad or sometimes larger, ciliate and commonly with scattered hairs on both surfaces ; peduncles as long as the petioles or longer ; pedicels strigillose, variable in length, but often relatively short ; sepals mostly 3-4 mm. long ; petals lightor pale-yellow, 7-10 mm. long ; filaments glabrous ; capsules columnar, 8-18 mm. long, finely pubescent, rather abruptly narrowed at the apex.
Type locality : Italy.
Distribution : Ontario to California, Bermuda, Florida, and tropical America ; also in the tropics generally and Europe.