Bacopa australis Souza (2001: 58)

Sosa, María De Las Mercedes, Moroni, Pablo & O’Leary, Nataly, 2018, A taxonomic revision of the genus Bacopa (Gratioleae, Plantaginaceae) in Argentina, Phytotaxa 336 (1), pp. 1-27 : 3-4

1. Bacopa australis Souza (2001: 58) . Fig. 1 .

Type:— BRAZIL. Paraná. Capanema, río Iguazú, J. Lindeman & H. Haas 3358 (holotype MBM!, isotype K!).

Herbs, annual, 5–15 cm tall, prostrate, few branched, ascending stems, strigose, sometimes villose, denser towards the apex. Leaves opposite, sessile, blade orbicular, sometimes ovate or elliptic, 4–10 × 3–9 mm, apex rounded, base rounded, margin entire, adaxial surface glabrous, abaxial surface sparsely pubescent, more densely on the veins. Flowers axillary, solitary, pedicels 10–30(–50) mm long, sub-glabrous, bracteoles absent. Calyx 5-lobed, the external dorsal lobe wide ovate, 3.6–4.1 × 2.8–3.2 mm, apex rounded, base cordate, the two lateral lobes ovate, 3.8–4 × 1.8–2 mm, apex obtuse, base cordate, hispid towards the apex and in the central vein, the two internal lobes linear, 2 – 3 × 0.45–0.5 mm, apex acute, hispid on the margins. Corolla white, blue, or pale blue, tube 3–5 mm long, glabrous; stamens 4; ovary glabrous, style deeply bifid, stigmatic apex smooth. Capsule ovoid, apex acute, 3.5–3.7 × 1.8–2 mm.

Distribution and habitat:—Native species from South America, present in southern Brazil and in northeastern Argentina, in the province of Corrientes. It grows between 0–500 m elev., frequent in flood pastures.

Taxonomic remarks:— Bacopa australis is similar to B. repens (Swartz) Wettstein in the prostrate habit, strigose pubescence, and absence of bracteoles, being distinguished by the androecium with two stamens (vs. four), and by the longer pedicel (10–50 mm vs. 1–5 mm). It is also similar to B. dubia Chodat & Hassl. , being distinguished by the strigose to villose pubescence (vs. slightly strigose); and by the corolla tube length (3–5 mm vs. 8–12 mm).

Selected specimens examined:— Corrientes: Itatí, ruta 12, 4 km E de acceso a Itatí, 23 Jan 1972, Krapovickas & Cristóbal 20816 (CTES!).

Figures

FIGURE 1. Bacopa australis. A. Plant aspect. B. Calyx. C. Portion of corolla opened, showing stamens. D. Calyx with one of the lateral lobes opened, showing gynoecium. E. Dorsal lobe, external view. F & G. Lateral lobes, internal views. H & I. Internal lobes (from Krapovickas et al. 17067, CTES).