Desmodium pachyrhizum Vogel 1838
Creators: name: Lima, Laura Cristina Pires
name: Queiroz, Luciano Paganucci De
name: Tozzi, Ana Maria Goulart De Azevedo
name: Lewis, Gwilym Peter
Publisher: name: Zenodo
Year: 2014
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Fabales
Fabaceae
Desmodium
Desmodium pachyrhizum

description: 20. Desmodium pachyrhizum  [pachyrhiza] Vogel, Linnaea 12: 97. 1838. Meibomia pachyrhiza (Vogel) Kuntze, Revis. Gen. Pl. 1: 197. 1891. Lectotype (designated here):— BRAZIL. F. Sellow s.n. (lectotype L!, isolectotypes E!, FOBN002260!, LE![2 sheets], M!, W!). Fig. 22.   
 Desmodium pachyrhizum f. intermedium Chodat & Hassl., Bull. Herb. Boissier, ser. 2, 4(9): 890. 1904. Lectotype (designated here):— PARAGUAY. campo Ipe, Serra de Maracaju, October, E. Hassler 5049 (lectotype G00070247!, isolectotypes BM!, G00070245!, G00070246![2 sheets], G00070248!, K!, P![2 sheets], W!).   
Erect, unbranched subshrub, 0.5–1.8 m tall, with a xylopodium; stems not virgate, slender, cylindrical, striate, glabrescent or sparsely puberulous-uncinate, not glaucous; internodes 1.3–4.2 cm long. Stipules 3–4 × 1.5–2 mm, triangular, not auriculate, semi-amplexicaul, inserted perpendicularly at the base of the leaf petiole, free from each other, apex caudate, margin ciliate, glabrescent, veins inconspicuous, caducous. Leaves unifoliolate; petiole 2–3 mm long, cylindrical, sulcate, sparsely or densely; stipels 2–3 mm long, subulate, margin straight, glabrescent,  
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persistent; leaflet concolorous, chartaceous, venation brochidodromous, primary, secondary, tertiary and quaternary veins prominent on the abaxial surface, indumentum tomentose or glabrescent on the primary, secondary and tertiary veins on the abaxial surface, adaxial surface puberulous-uncinate, uncinate hairs covering both surfaces, leaflet 5.2–9 × 0.6–2 cm, elliptic, linear, ovate or ovate-lanceolate, base oblique, obtuse or truncate, apex subacute, retuse or obtuse, mucronate. Inflorescence a terminal pseudoraceme or paniculate; the main axis longer than the adjacent leaves, 48–75 cm long, sparsely or densely hispid and uncinate, 2 flowers per node; primary bract 3–4 mm long, lanceolate, margin straight, hirsute and uncinate on the outer surface, caducous, veins conspicuous on the outer surface; secondary bract 2–3 mm long, linear, margin straight, hirsute–uncinate on the outer surface, caducous, veins inconspicuous on the outer surface; pedicel 7–13 mm long, sparsely or densely hispid and uncinate. Flowers 4–7 mm long; calyx bilabiate, tube campanulate, 1–1.5 mm long, hirsute on the outer surface; upper lip bifid, slightly fused, the 2 teeth joined for a ca. ¾ of their length, acute, ca. 0.2 mm long; lower lip trifid, lateral tooth triangular, 1.5–2 mm long, central tooth lanceolate, 2–2.5 mm long; corolla lilac, standard 4.5–7 × 2.5–6.5 mm, obovate or broadly obovate, apex obcordate, maculate at the base, claw 0.5–1 mm long; wing petals 4.5–7 × 2–3 mm, oblong, apex obtuse, without callosities, claw ca. 1 mm long; keel petals 4–7 × 1.5–2 mm, narrowly obovate, apex subacute, with callosities, claw 2.5–3 mm long; androecium monadelphous, 4–7 mm long, vexillary stamen partially fused with the other from the base 0.5–1 mm long; ovary 2.5–3.5 mm long, sericeous, stipe 0.5–0.8 mm long, glabrous. Loment 1.5–2.2 cm long, stipe ca. 1 mm long, glabrescent, isthmus central, both margins sinuate and lower suture sinuate; articles uniform 3–6, 3–4 × 2.5–3.5 mm, ovate-elliptic, not tortuous, indehiscent, subcoriaceous, veins inconspicuous, densely puberulous-uncinate and sparsely hirsute. Seed ca. 2 × 1.5 mm, oblong, hilum subcentral.  
 Selected specimens examined:— BRAZIL. Goiás: Goiânia: as margens do Ribeirão João do Leite, 1 February 1969, fl., J . A. Rizzo & A. Barbosa 3645 (UFG). Mato Grosso: s. mun.: divisa com município de Tangará da Serra e Nova Olímpia, 15 December 1993, fl., M . Macedo & R. Godinho 3575 (INPA). Mato Grosso do Sul: Dourados: terreno baldio, na rua Cláudio Groelzer, no Jardim Alvorada, 17 February 2009, fl., fr., L . C. P. Lima et al. 529 (HUEFS). Minas Gerais: Campina Verde: Ca. 17 Km da cidade, em direção a Ituitaba, 15 January 2005, fl., fr., J . P. Souza et al. 3906 (ESA, HUEFS); Pirapora: Cocal- estrada de Guaicuhy, 18 December 1937, fl., M . Burret et al. 10085 (BHCB, SP). Paraná: Curitiba: Jardim Botânico de Curitiba, 3 January 2006, fl., fr., J . Cordeiro 2320 (HUEFS, RB, SPF). Rio Grande do Sul: Itaara: Reserva do Ibicuí-Mirim, após o Passo da Rede, 5 March 2009, fl., fr., L . C. P. Lima et al. 554 (HUEFS). Santa Catarina: Lages: ca. 10 Km Sde Lages, 27 December 1966, fl., fr., J . C. Lindeman & J. H. Haas 3713 (MBM, U). São Paulo: Pedregulho: Parque Estadual Furnas do Bom Jesus, 21 March 2004, fl., fr., D. Sasaki & M . F. A. Calió 972 (SPF).   
 Distribution and Ecology:— D. pachyrhizum is recorded for Argentina, Brazil, Bolivia, Colombia, Ecuador, Mexico, Paraguay, Uruguay, and Venezuela (Dietrich 1847, Chodat & Hassler 1904, Rusby 1927, Cuello & Aymard 1991, Capdevila 1994, Izaguirre & Beyhaut 1998, Vanni 2001, Lima et al. 2010). In Brazil the species occurs in grassland and pasture in the States of Goiás, Minas Gerais, Mato Grosso, Mato Grosso do Sul, Paraná, Rio Grande do Sul, Santa Catarina, and São Paulo.   
 Conservation Assessment:— Least Concern (LC), not endangered (IUCN 2001).   
 Phenology:— flowering and fruiting from October to July.   
 Etymology:— from the Greek pachy (= thick) + rhizi (= roots), a reference to the thick root.   
 Common Name:— carrapicho; pega-pega.   
 Taxonomic notes:— unifoliolate leaves, pedicels more than 7 mm long, flowers to 7 mm long, and elliptic to ovate-elliptic, puberulous-uncinate and hirsute articles are diagnostic characters of this species and help to differentiate it from morphologically similar unifoliolate species, such as D. microcarpum, D. platycarpum, D. polygaloides, and D. sclerophyllum.   
 Specimens of D. pachyrhizum are commonly encountered in herbaria as D. sclerophyllum due to similarities in vegetative characters, such as leaflet number (unifoliolate) and shape. However, D. pachyrhizum has no indumentum on the tertiary veins of the abaxial leaflet surface (vs. veins pubescent in D. sclerophyllum), has a pilose ovary (vs. glabrous), pedicels 7–13 mm long (vs. 3–6(– 7) mm long), and elliptic, hirsute articles (vs. orbicular, puberulous-uncinate).   
 Vogel (1838) described this species as Desmodium “ pachyrhiza ” in Linnaea. Bentham (1859) presented it as Desmodium pachyrhizum, which is considered the correct spelling (articles 23.5, 32.7, and 62.3 of the ICBN, McNeill et al. 2006), as Desmodium is masculine.   
 DESMODIUM (LEGUMINOSAE, PAPILIONOIDEAE) IN BRAZIL   
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The material cited in the protologue of this species by Vogel (1838) was not found in the Berlin herbarium (B) and the conclusion is that it was destroyed during World War II. Fortunately a photograph (FOBN002260!) and duplicates of the collection “Brasilia, Sellow” identified with the handwriting of Vogel were examined in the herbaria E, L, LE, M, and W. Of these, the material deposited in the Lherbarium is here selected as the lectotype.  
 Chodat & Hassler (1904) described Desmodium pachyrhizum f. intermedium characterised by ovate leaflets. Schindler (1928) recognised it as a synonym of Meibomia pachyrhiza (currently D. pachyrhizum), which is accepted in this study because leaflet shape is quite variable on individuals and within populations of this species. Among the type specimens of D. pachyrhizum f. intermedium analysed, G00070247 is selected as the lectotype following the criteria established in the methodology section of this paper.
description: Published as part of Lima, Laura Cristina Pires, Queiroz, Luciano Paganucci De, Tozzi, Ana Maria Goulart De Azevedo & Lewis, Gwilym Peter, 2014, A Taxonomic Revision of Desmodium (Leguminosae, Papilionoideae) in Brazil, pp. 1-119 in Phytotaxa 169 (1) on pages 64-67, DOI: 10.11646/phytotaxa.169.1.1, http://zenodo.org/record/10089817