Ludwigia hyssopifolia (G.Don) Exell

Rocha, Amanda Macêdo & Melo, José Iranildo Miranda de, 2020, Diversity and distribution of Ludwigia (Onagraceae) in Paraíba State, Northeastern Brazil, European Journal of Taxonomy 639, pp. 1-24 : 13-15

Ludwigia hyssopifolia (G.Don) Exell

Figs 4 f–h, 5a, 6a–k

Material examined

BRAZIL – Paraíba • Alagoinha, Estação Experimental ; 24 Oct. 1942; Lauro Xavier s.n.; JPB [105] • Areia ; Apr. 1992; fl.; M.P. Agra & M.G. Silva 1829; JPB • Bananeiras, Goiamunduba Reserve ; s.d.; fl. and fr.; E.C. Costa & L.B.S. Pereira 203; HACAM • Cabaceiras ; 26 Aug. 1982; fl.; P. Cascon & J. Oliveira s.n.; JPB [17444] • Cruz do Espiríto Santo ; 3 Nov. 1987; fl.; L.P. Felix & E.C. Silva 1867; EAN • Ingá, Itacoatiara, microrregion of Piemonte da Borborema ; 29 Apr. 1994; fl.; M.P. Agra & E.A. Rocha 2857; JPB • João Pessoa, river Jaguaribe, close to Conjunto Castelo Branco ; 13 Jul. 1982; fr.; O.T. Moura 215 A; JPB • Lagoa Seca, Cachoeira do Pinga ; 11 Jul. 2017; fl.; A.M. Rocha 25; HACAM • Passagem, Fazenda ABA ; 6 Apr. 2017; fl. and fr.; A.M. Rocha 14; HACAM • Patos, Várzea do Jurema ; 29 Jul. 2011; C. Torres 98; CSTR • Pombal, Sítio Maniçoba II , bank of the Riacho dos Carneiros ; 15 Jul. 2011; fl. and fr.; I.S. Queiroga 107; CSTR • Remígio ; 23 Mar. 1975; fl.; V. Perazzo Barbosa 259; RB • Santa Luzia ; 20 Apr. 2017; fl. and fr.; A.M. Rocha 16; HACAM • Sapé, Açude São Salvador ; 10 Jun. 2014; fl. and fr.; H.O. Machado-Filho 549; CSTR • Sousa , Vale dos Dinossauros; 17 May 2005; bud; P.C. Gadelha-Neto 1379; JPB .

Description

Herbs to subshrubs, 0.4–0.87 m high, erect; branches angular, glabrous. Leaves sessile; blade 6.7–8 × 2–2.5 cm, with entire margin, membranous, elliptic to lanceolate, with cuneate apex and decurrent base, glabrous. Flowers tetramerous, sessile; bracteoles 2, near the base of hypanthium, smaller than 1 mm in length; sepals 5–6 × 1.8–2 mm, green, lanceolate, with acute apex, external and internal faces glabrous; petals 4.5–5 × 2.8–3 mm, golden yellow, elliptic, with acute apex; hypanthium ca 8 mm long, 4-locular; style ca 2 mm long, stigma capitate; stamens 8, anthers globose; plain nectariferous disk with depressed nectaries, pilose, surrounding the base of each epipetalous stamens. Capsule 25–27 × 1.5–2 mm, cylindrical, slightly wide at the distal region, internally dimorphic, glabrous. Seeds smaller than 1 mm in length, fusiform, pluriseriate and not embedded in endocarp in the upper part of the capsule, uniseriate and embedded in endocarp in the lower section of the capsule, raphe non-inflated, with diameter narrower than the body of the seed.

Distribution

Ludwigia hyssopifolia is a pantropical species ( Raven 1963; Zardini & Raven 1997). In Brazil, it is distributed in the North (AC, AM, PA, RO, RR), Northeast (AL, BA, PE), Central-West (MS, MT), Southeast (MG, SP) and South (PR) regions, associated with Amazon, Atlantic Rainforest and Pantanal phytogeographic domains (Vieira 2015).

Habitat and phenology

In the study area, L. hyssopifolia occurs from the Sertão region to the Mata region. It is found on humid soil, in swampy environments, or close to water courses, associated with the Caatinga and the Atlantic Rainforest. Flowers occur from January to October and fruits from May to September.

Conservation status (Paraíba State, Brazil)

The extent of occurrence (EOO) of Ludwigia hyssopifolia is 14 285.685 km 2, within the limit for the Vulnerable category (EOO less than 20 000 km²). The species’ area of occupancy (AOO) is 80 km 2, within the limit for the Endangered category (criterion B2: less than 500 km 2). However, L. hyssopifolia is recorded from more than 5 locations in the Paraíba State, and other conditions were not met to apply the criterion B2 (no evidence of populations fragmentation or decline, no threats or habitat loss). In the Paraíba State, the species falls under the category Vulnerable (VU), defined according to criterion B1ab(ii,iii) because only one record occurs in a conservation area, the Monumento Natural do Vale dos Dinossauros, in Sousa, the other locations where the species occurs are not protected areas and are affected by urban expansion.

Note

Most voucher specimens of L. hyssopifolia in the consulted herbaria are misidentified as L. erecta . The two species are similar, with tetramerous flowers with yellow petals, up to 5 mm long. However, the internaly dimorphic capsule with free pluriseriate seeds in the distal part and uniseriate seeds embedded in endocarp in the proximal part is the most important feature that distinguishes L. hyssopifolia from the others species. Dimorphism of the capsule characterizes Ludwigia sect. Fissendocarpa which is monospecific ( Zardini & Raven 1992; Wagner et al. 2007).

Figures

Fig. 4. a–c. Ludwigia erecta (L.) H.Hara. a. Habit showing pneumatophore roots (arrow). b. Flower. c. Fruits. – d–e. L. helminthorrhiza (Mart.) H.Hara. d. Habit showing spongy pneumatophore roots (arrow). e. Flower. – f–h. L. hyssopifolia (G.Don) Exell. f. Habit. g. Branch with flowers and fruits. h. Flower. Photos: a, c–f = A.M. Rocha, b = F.C.P. Costa, g–h =H.C. Araújo.