Ludwigia nervosa (Poir.) H.Hara

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 : 17-18

Ludwigia nervosa (Poir.) H.Hara

Figs 5b , 8 h–n

Material examined

Material from Paraíba State

BRAZIL – Paraíba • Mataraca, between Camaratuba and the border with Rio Grande do Norte; 8 Feb. 1968; fl.; A. Lima 68-5312; IPA • Rio Tinto, Mata do Maracujá, Sema III ; 23 May 1990; bud and fl.; L.P. Félix et al. 3023; EAN .

Additional material examined

BRAZIL – Bahia • Belmonte, Barrolândia, Estação Experimental “Gregorio Bondar” CEPLAC; 13 May 1993; fl. and fr.; W. Thomas et al. s.n.; NY[9907] .

Description

Shrubs, 2.5–3.5 m high, erect; branches cylindrical, glabrous to pilose. Leaves subsessile; blade 4.9– 5.3 × 0.9–1 cm, with entire margin, chartaceous, lanceolate to oblong-lanceolate, with acute apex and acute to obtuse base, glabrous, with pubescent nervure. Flowers tetramerous, pedicellate; pedicels ca 1 cm long; bracteoles not visible; sepals 8–12 × 4 mm, green, lanceolate, with attenuate apex, external face sparsely pubescent; petals ca 14 × 12 mm, pale yellow, orbicular to obovoid, with rounded apex; hypanthium ca 1 cm long, 4-locular; style ca 2 mm long, stigma globose; stamens 8, anthers linear; high nectariferous disk, ca 2 mm high, with depressed nectaries, densely pilose, surrounding the base of each epipetalous stamens. Capsule ca 13 × 5 mm, obconic, 4-angled, internally non-dimorphic, hirsute to glabrous. Seeds 1–1.5 mm long, oblongoid, transversally striated, pluriseriate, not embedded in endocarp, raphe non-inflated, narrower than the body of the seed.

Distribution

Ludwigia nervosa is distributed from South Mexico to Bolivia and Paraguay ( Zardini & Raven 1997). In Brazil, it is distributed in the North (AM, AP, PA, RO, RR, TO), Northeast (BA, MA, PE, PI), Center- West (DF, GO, MS, MG), Southeast (ES, MG, RJ, SP) and South (PR) Region, in the phytogeographic domains of the Amazon, Atlantic Rainforest, Savanna (Cerrado), Caatinga and Pantanal (Vieira 2015).

Habitat and phenology

In the studied area, L. nervosa occurs only in the mesoregion Mata, in swampy environments, associated with Atlantic Rainforest vegetation. Flowers occur in February and May.

Conservation status (Paraíba State, Brazil) The extent of occurrence (EOO) of Ludwigia nervosa is 0 km2 and its area of occupancy (AOO) is

8 km 2. According to the IUCN criteria, the species is assessed as Critically Endangered (CR) under criterion B1ab(i,ii,iii)+2ab(i,ii,iii). Ludwigia nervosa is only known from 2 specimens in Paraíba State, one of which was collected almost 50 years ago, and the second 30 years ago. The biome with which it is associated in Paraíba State is frequently degraded by the expansion of sugarcane monocultures, posing a potential threat to the species and possibly causing a continuous decline of its population.

Note

Ludwigia nervosa differs from other Ludwigia species in the studied area by its chartaceous leaves, high nectariferous disk and obconic tetrangular capsule with pluriseriate seeds not embedded in endocarp. Seed characteristics were retrieved from Zardini & Raven (1997).

Figures

Fig. 5. Map showing the geographic distribution of Ludwigia L. species in the Paraíba State, Brazil.

Fig. 8. a–g. Ludwigia octovalvis (Jacq.) P.H.Raven, A.M. Rocha 08. a. Habit. b. Flower. c. Sepal. d. Petal. e. Fruit. f. Transversal cut of the fruit. g. Seed. – h–n. L. nervosa (Poir.) H.Hara, L.P. Félix et al. 3023. h. Habit. i. Flower. j. Sepal. k. Petal. l. Stamen. m. Hypanthium with high nectariferous disk. n. Fruit. Illustrations by R.M.A. de Carvalho.