Begonia heliantha Tebbitt

Moonlight, Peter. W., Jara-Muñoz, Orlando A., Purvis, David A., Delves, Jay, Allen, Josh P. & Reynel, Carlos, 2023, The genus Begonia (Begoniaceae) in Peru, European Journal of Taxonomy 881, pp. 1-334 : 39-41

3. Begonia heliantha Tebbitt

Figs 16 , 17A

Edinburgh Journal of Botany 73 (1): 145 ( Tebbitt 2016).

– Type: PERU – Puno Region: Prov. Sandia • Entre Sandia y Tambopata ; 1700–2200 m a.s.l.; [14°15′ S, 69°25′ W]; 7 Aug. 1965; J.C. Vargas Calderón 16417ª; holotype: US [ US01269467 ]; isotype: CUZ [2].

Tebbitt (2020: 69).

Etymology

The epithet derives from the Greek words ‘ helios ’ and ‘ anthos ’, meaning ‘sun’ and ‘flower’. This references the bright yellow, ‘sun-like’ flowers of the species.

Specimens examined

PERU – Puno Region: Prov. Sandia • ca 17 km on road below Sandia; 14°13.684′ S, 69°24.736′ W; ca 1600 m a.s.l.; 16 Feb. 2002; R.T. Pennington, T.D. Pennington & A. Daza 1113; E [ E00274868 ], K, MOL.

Description

Caulescent, tuberous herb, to 20 cm high. Tuber ellipsoid, 1.1–2.5 × 1.1–2.5 cm, with one growing point. Stem erect, unbranched; internodes to 3.1 cm long, to 2 mm thick, succulent, red, sparsely pubescent. Stipules persistent, ovate, 1–3.5 × 0.5–2 mm, apex acute, aristate, opaque, brown, glabrous, margin fimbriate, ciliate. Leaves 3–6, alternate, basifixed; petiole 1.7–5 cm long, red, densely glandular-pubescent; blade asymmetric, ovate, to 10 × 5 cm, succulent, apex acute to acuminate, base obliquely cordate, basal lobes not overlapping, sinus to 15 mm deep, margin lacking lobes or shortly-lobed, lobes triangular-crenate, dentate, ciliate, upper surface green with paler veins, sometimes flushed black between the veins, moderately pubescent, lower surface pale green, densely pubescent on the major veins, moderately pubescent on the lamina, veins palmate but with 1 primary vein, 7–9 veined from the base, 1–3 secondary veins on the larger side, 1–2 on the smaller side. Inflorescences 1–3, bisexual, axillary, erect, cymose, with up to 2 branches, bearing up to 3 staminate flowers and 2 pistillate flowers, protandrous; peduncle to 16 cm long, red, moderately glandular-pubescent, bracts persistent, obovate to ovate, 1.25–6 × 0.5–4 mm, translucent, brown, glabrous, apex acute to rounded, margin lacerate, ciliate. Staminate flowers: pedicels to 15 mm long, moderately-pubescent; tepals 4, spreading, outer 2 elliptic to ovate, 8–20 × 5–11 mm, apex obtuse, bright yellow, glabrous, margin entire, aciliate, inner 2 narrowlyobovate, 8–15 × 3–7 mm, apex obtuse, bright yellow, glabrous, margin entire, aciliate; stamens 25–35, spreading, yellow, filaments 1–2 mm long, free, anthers cuboid, ca 1 × 0.5 mm, dehiscing via lateral slits, connectives not extended, symmetrically basifixed. Pistillate flowers: pedicels to 14 mm long; bracteoles 2, positioned directly beneath the ovary, lanceolate to lanceolate-ovate, ca 2 × 1 mm, apex acute, opaque, colour unknown, glabrous, margin entire, ciliate; tepals 5, rarely 4 ( Fig. 17D ), subequal, deciduous in fruit, spreading, elliptic to ovate, 6–12 × 4–5 mm, apex obtuse, bright yellow, glabrous, margin entire, aciliate; ovary body ellipsoid to spheroid, 3–9 × 3–5 mm, red, glabrous, unequally 3-winged, wings triangular, largest 3–12 × 5–10 mm, smallest 3–5 × 3–5 mm; 3-locular, placentae unknown; styles 3, yellow, free, ca 4 mm long, once-divided, stigmatic papillae in a spirally-twisted band. Fruiting pedicel to 30 mm long. Fruit body ovoid, to 9 × 6 mm, drying brown, wings same shape as in ovary, the largest expanding to 10 × 16 mm, the smallest expanding to 7 × 7 mm.

Proposed conservation assessment

Assessed by Tebbitt (2016) as Data Deficient ( DD). We have since visited the type locality and observed a stable population of ca 5 k plants growing along a 1 km stretch of the main 34 H road through Sandia Province. It is likely that the population would decline rapidly if the road were improved, or the quantity of traffic increased, which would be grounds for reassessing the species as Critically Endangered. Accordingly, we assess B. heliantha as Vulnerable ( VU D2) under IUCN criteria.

Identification notes

Within Peru, B. heliantha is unique in its bright yellow flowers. When sterile, it could be confused with B. herrerae , which is also a tuberous herb with a pubescent indumentum and ovate, obliquely cordate leaves with an acuminate apex. They differ in their indumentum, which is glandular in B. heliantha and non-glandular in B. herrerae .

Distribution and ecology

Endemic to Peru and Puno Region ( Fig. 17A ). Known from middle montane Forest at an elevation of 1600–2200 m a.s.l. Begonia heliantha has been collected on moist shaded rocks in February and August but as a tuberous species likely dies back at some point in the year.

Figures

Fig. 16. Begonia heliantha Tebbitt. A. Habitat. B. Habit. C. Pistillate flower, oblique front view. D. Staminate and pistillate flower, front view (note, the pistillate flower is unusual in having four tepals and two styles). All photographs by J.P. Allen in Sandia Province, Puno Region.

Fig. 17. Distribution of Begonia sect. Australes L.B.Sm. & B.G.Schub. in Peru and surrounding countries. A. B. herrerae L.B.Sm. & B.G.Schub. (red) and B. heliantha Tebbitt (blue). B. B. veitchii Hook.f. var. veitchii (red) and B. veitchii var. machupicchuensis Tebbitt (red). Black lines indicate country borders, grey lines indicate major administrative divisions, blue lines indicate rivers, and shading indicates elevation.