Oxalis refracta Saint-Hilaire 1825
Creators: name: Nuernberg-Silva, Anelise
name: Fiaschi, Pedro
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Oxalidales
Oxalidaceae
Oxalis
Oxalis refracta

description: 9. Oxalis refracta Saint-Hilaire (1825: 119). Type (lectotype designated by Lourteig 1983: 72, first-step; second-stepdesignated here):— URUGUAY, sur la montagne appelée Cerro áspero près Rocha, October 1816 –21,A. Saint-Hilaire
C²2080 (P02440316! image of the lectotype available at https://plants.jstor.org/stable/viewer/10.5555/al.ap.specimen. p02440317; isolectotypes: F0066532F [web]!, P02440318!, MPU018619 [web]!). (figs. 12, 15).
= Acetosella amara var. glandulosa Kuntze (1898: 30). Type (lectotype designated by Lourteig 1983: 72):— URUGUAY. Montevideo, Cerro de Montevideo, November 1892, C.E.O. Kuntze s.n. (NY00370275 [web]! image of the lectotype available at https://plants. jstor.org/stable/viewer/10.5555/al.ap.specimen.ny00370275 ≡ Oxalis amara var. glandulosa (Kuntze) R. Knuth (1930: 433).
= Oxalis subcorymbosa Arechavaleta (1900: 238). Type (lectotype designated by Lourteig 1983: 71):— URUGUAY. Piriápolis, Pan de Azúcar, s.d., J. Arechavaleta s.n (MVN [transferred to WOS] fide Lourteig 1983).
= Oxalis uruguayensis R. Knuth (1919: 300). Type (lectotype designated by Lourteig 1983: 71):— ARGENTINA. Entre Ríos, Concepcion del Uruguay, Quinta del Colegio, campo, 13 September 1875, P.G. Lorentz 272 (GOET008545 [web]! image of the lectotype available at https://plants.jstor.org/stable/viewer/10.5555/al.ap.specimen.goet008545?loggedin=true; isolectotypes CORD, S-R-10012 [web]!, WOS) ≡ Oxalis kuntzeana Norlind (1926: 19) ≡ Oxalis knuthii Herter (1930: 75).
= Oxalis subcorymbosa var. viscosíssima Norlind (1926: 20). Type (lectotype designated by Lourteig 1983: 72):— ARGENTINA. Buenos Aires, Sierra de la Ventana, November 1904, P. Dusén 6327 (S-R-9814 [web]! image of the lectotype available at https://plants.jstor. org/stable/viewer/10.5555/al.ap.specimen.s-r-9814) ≡ Oxalis viscosissima (Norlind) Cabrera (1965: 11).
Decumbent subshrub. Stem ca. 30 cm long; shorter hairs 0.1–0.2 mm long, patent, moderate to abundant; longer hairs 0.5–1 mm long, patent, ascending and descending, moderate to abundant; glandular hairs 0.2–3 mm long, sparse to abundant, in some individuals remaining only the shorter hairs; internodes 0.2–5 cm long. Stipules 3.5–4 × 2.5–3 mm, rectangular, connate to the petiole, hairs ca. 1 mm long on the margin, patent, abundant; petiole 1–4 cm long; hairs as in stem, glandular hairs 0.2–0.5 mm long, patent, sparse to moderate; pulvina ca. 0.3 mm long. Leaf blades 7–10 × 5–7 mm, coriaceous, widely depressed obtrullate to very widely obtrullate, slightly discolorous, the base cuneate, the apex cleft, generally asymmetrical with respect to the mid vein; hairs ca. 1 mm long, appressed, moderate to abundant; glandular hairs 1–1.5 mm long, sparse or abundant on both surfaces. Dichasia with 2–3 flowers, longer than the leaves; peduncle 2.5–5.5 cm long; shorter hairs 0.1–0.2 mm long, patent, moderate to abundant; longer 0.5–1 mm long, patent, ascending and descending, moderate to abundant; glandular hairs 0.2–3 mm long, patent, sparse to abundant; bracts 0.5 × 1.5–2 mm, lanceolate, hairs 0.2–1 mm long: bracteoles 0.5 × 1 mm, lanceolate. Pedicels 1–15 mm long; sepals 4–9 × 1.3 mm, base rounded, apex acute, hairs ca. 1 mm long, ascending and patent, simple and glandular, abundant to very abundant; petals yellow, 13.5–18 mm long, spatulate, the apex crenate-denticulate, adaxially with moderate glandular hairs; shorter stamens 2.5–4.5 mm long, glabrous, longer ca. 5–9 mm long, with hairs ascending; pistil 3–10 mm long, hairs ascending, abundant, simple and/or glandular hairs, stigmas papillose. Capsules 5–7 × 4–6 mm, widely ovoid to ovoid, 5-lobed, glandular hairs ca. 1 mm long, patent, abundant to very abundant. Seeds 3–5 per locule, 2.4–2.8 × 1.4–1.7 mm, elliptic, the base rounded, the apex acute.
Distribution and habitat: —This species occurs in grasslands and forest edges in the Pampa domain and neighbor areas, with records from Argentina, Uruguay and Brazil (Rio Grande do Sul) (fig. 15).
Phenology: —Flowers and fruits have been collected from August to December.
Conservation status: — Oxalis refracta has a wide extent of occurrence (EOO = 623,991 km 2), but its distribution is discontinuous, with usually small populations occupying in total an area of occupancy of about 76 km ². Its habitat suffers an accelerated decline due to soil use conversion to agricultural activities. Oxalis refracta has not been recorded in protected areas, which are few in the Pampa domain, but its habitat still has good connectivity, so we consider that it should be categorized as near threatened (NT).
Typification of Oxalis refracta: —In the original description, Saint-Hilaire (1825) proposed a beta-variety (named “ debilis ”) for his Oxalis refracta (see treatment of this name under O. niederleinii). The type material of Oxalis refracta var. refracta (the alfa-variety, see Art. 26.3 of ICN) was collected in “ sylvulis humidis umbrosisque ad ripas rivuli dicti Arroio del Rosario, provincial Cisplatina ”, and lectotypified by Lourteig (1983), who mentioned Saint-Hilaire C²2080 at P as the “ holotype ”. We traced two samples of Saint-Hilaire C²2080 at P, and according to the Art. 9.17 of ICN, we selected P02440316 as the second-step lectotype, because it is the most complete specimen and perfectly fits the original description. These specimens (Saint-Hilaire C²2080) correspond to a morphological extreme in the continuum of hair density of Oxalis refracta, with a much sparser indumentum than at most specimens examined here.
Taxonomic notes: — Oxalis refracta is similar to O. niederleinii, from which it can be distinguished by glandularviscid hairs up to ca. 1.5 mm long, which are abundant to very abundant (rarely sparse) throughout the plant (vs. glandular hairs ca. 0.2 mm long, sparse to moderate in reproductive organs in O. niederleinii), more densely arranged leaves (vs. sparse), smaller leaflet blades (7–10 × 5–7 mm vs. 4–20 × 6–20 mm), shorter peduncles (2.5–5.5 mm vs. 3,5–12,5 cm long), inflorescences with 2–3 flowers (vs. up to 13 flowers), and larger capsules [5–6 (7–10) × 12–15 mm vs. 2–5 × 3–5 mm].
Additional note: —Due to its dense glandular hairs, Oxalis refracta can become very sticky, and there are reports of allergenic contact likely due to these glandular hairs content (Laura S. Fetter, pers. comm.).
Specimens examined: — ARGENTINA. Buenos Aires: Tornquist, Co Ventana 400 msm, 20 October 1979, C. A. Naranjo 482 (SI); Tandil, La Cascada, 25 November 1937, N. S. Troncoso 1266 (SI); 12 November 1907, C. M. Hicken 19811 (SI); Entre Ríos: Concepción del Uruguay, Quinta del colegio, 13 September 1875, P. G. Lorentz 272 (S-R-10012 [web]); Diamante, quebrada del cementerio, 17 December 1960, A. Burkart 22197 (SI); 3 November, A. Burkart 27978 (SI); Punta Gorda, 10 November 1985, N. M. Bacigalupo 1457 (SI); Gualeguaychu, Punta Caballo, Barranca, 13 December 1974, A. Burkart 30895 (SI); Ea. Rincón de Landa, sobre el Río Uruguay, a la altura de Perdices, 30 October 1990, N. M. Bacigalupo 1457 (SI); La Paz, Santa Elena, Barrancas, 23 October 1971, A. Burkart 28696 (SI); A. Burkart 28696 (SI); Hernandarias, Pto. Víbora, 5 December 1986, E. R. Guaglianone et al. 202 (SI); La Pampa: Lihuel Calel, Sierra de L. Calel, co. “de la Sociedad”, ladera E, en cañadón, 16 October 1979, D. de Azkue s.n. (SI 111691); Misiones: Apostoles, Cnia las Tunas, 3 October 1995, M. E. Torri 220 (CTES); Escuela Agrotécnica Pascual Gentilini, 21 August 1978, A. L. Cabrera & N. S. Troncoso 29269 (SI); Ruta Prov. 1. Arroyo Tunas, 27°55’S, 55°37’W, 24 September 2000, M. E. Múlgura 2326 (SI); Candelaria, Loreto, camino hacia ruta de Santa Ana Oberá, 27°20’S - 55°32’W, 22 September 2000, M. E. Múlgura 2240 (SI); BRAZIL. Rio Grande do Sul: Giruá, Granja Sodol, 26 September 1965, K. Hagelund 3872 (ICN); s.d., K. Hagelund 1109 (ICN); Santana do Livramento, João Duarte, Cerro do Registro, 11 November 2009, E. Barbosa et al. (RB 615285); Agudo, 10 October 2015, J. P. R. Ferreira 773 (FLOR); São Pedro do Sul, 28 October 2016, A. Nuernberg 1829 (FLOR); URUGUAY. Lavalleja: Minas, Cerro Arequita, 11 October 1970, A. Krapovickas 16153 (CTES); Maldonado: Piriapolis, Cerro del Toro, 34°51’45’’S, 55°15’03’’W, 18 October 2010, M. E. Morrone 6328 (SI); Cerro Pan Azucar, 13 October 1970, A. Krapovickas 16319 (CTES); Montevideo: Montevideo, Martínez 560 (SI); Sierra de Solís, C. E. O. Kuntze s.n. (NY-00370276 [web]).
description: Published as part of Nuernberg-Silva, Anelise & Fiaschi, Pedro, 2021, Taxonomic revision and morphological delimitation of Oxalis sect. Ripariae (Oxalidaceae), pp. 125-159 in Phytotaxa 529 (1) on pages 149-150, DOI: 10.11646/phytotaxa.529.1.11, http://zenodo.org/record/5814168