Begonia comestibilis D.C.Thomas & Ardi

Thomas, Daniel C. & Ardi, Wisnu H., 2020, Synopsis of Begonia (Begoniaceae) of southwest Sulawesi and the Selayar Islands, Indonesia, including one new species, Phytotaxa 437 (2), pp. 73-96 : 78-80

3. Begonia comestibilis D.C.Thomas & Ardi in Thomas et al. (2011: 226) ( Fig. 1 & 2 )

Sect. Petermannia

Type:— INDONESIA. Sulawesi, Sulawesi Selatan, Katemujotup [Ketemu Jodoh] waterfall, alt. 1030 m, 11 April 2009, D.C. Thomas & W.H. Ardi 09-62 (holotype E[00502338]!; isotype E[00502339]!, BO!) .

Description:— Perennial, erect, monoecious herb to ca. 80 cm tall. Stem branched; internodes 4‒13 cm long, reddish, glabrous except for microscopic glandular hairs. Leaves alternate; stipules caducous, 13‒17 × 6‒12 mm, elliptic to oblong, midrib abaxially prominent, apex narrowed into bristle up to 4 mm long, glabrous, greenish-reddish; petioles 4–18 cm long, reddish, glabrous; lamina usually excentrically peltate, sometimes some leaves with basifixed laminas, coriaceous, 8–17.3 × 4.5–10.5 cm, ovate to elliptic, asymmetric, leaf margin slightly sinuate close to the petiole (excentrically peltate leaves) or base cordate and lobes not overlapping (basifixed laminas), apex acuminate, margin dentate to serrate to bidentate or biserrate, teeth not bristle-pointed, adaxial surface green, smooth, glabrous; abaxial surface pale green, glabrous; venation palmate-pinnate, primary veins 5–6, actinodromous, secondary veins craspedodromous. Inflorescences: protogynous; female inflorescences 2-flowered, usually one node below male inflorescence part, peduncles 1‒1.5 mm long, reddish, glabrous, bracts stipule-like, caducous, ca. 13 × 6.5 mm, elliptic to oblong, pale green or reddish-green, glabrous; male inflorescences paniculate-cymose, composed of up to 5 subumbellate partial inflorescences, each with up to 10 flowers, peduncle of male inflorescence 9−38 mm long, reddish, glabrous, bracts caducous, 10‒15 × 9‒15 mm, broadly ovate to suborbicular, pale green or reddish-green, glabrous. Male flowers: pedicels 15–31 mm long, whitish-greenish, glabrous; tepals 2, white, 8–14 × 11–17 mm, broadly ovate to suborbicular, base slightly cordate, apex rounded, outer surface glabrous; androecium of ca. 76‒92 stamens, yellow, filaments up to ca. 2 mm long, slightly fused at the very base, anthers ca. 0.9‒1.5 mm long, obovate to oblong, dehiscing through unilaterally positioned slits> ½ as long as the anthers. Female flowers: pedicels 6−10 mm long, greenish, reddish at base, glabrous; tepals 5, white with pinkish veins, subequal, 7–18 × 3–11 mm, obovate to elliptic, outer surface glabrous; ovary 7–11 × 3–4 mm (excluding the wings), ellipsoid, wings 3, subequal, base rounded to cuneate, apex rounded to subtruncate, widest point up to 7 mm (subapically), glabrous, locules 3, placentation axile, placentae bilamellate; style ca. 4.5 mm long, basally fused, 3–branched, each stylodium bifurcate in the stigmatic region, stigmatic surface a spirally twisted papillose band, branches yellowish, stigma orange. Fruit: semi-fleshy, indehiscent; peduncles to 1.5 mm long; pedicels 6–10 mm long, glabrous; seed-bearing part 17−26 × 6−10 mm (excluding the wings), ellipsoid, wing shape as for ovary, glabrous. Seeds barrel-shaped, ca. 0.3−0.4 mm long.

Distribution:— Indonesia, endemic to Sulawesi: Central, West and South Sulawesi provinces ( Fig. 1C ).

Habitat:— Lowland to upland rain forest floor species, in primary to strongly disturbed vegetation, observed on slopes and road embankments, in full to partial shade, sometimes in open and sun-exposed habitats (plants with signs of sun damage), at ca. 40–1100 m elevation.

Notes:— The vast majority of species in Begonia section Petermannia has winged, dry capsules that split open along the wing attachment. There are several Sulawesi species including B. comestibilis , however, that have apparently indehiscent fruit. Begonia imperfecta Irmscher (1913: 367) and B. vermeulenii D.C.Thomas ( Thomas et al. 2011: 248) have wingless, indehiscent fruits with relatively thick pericarps; B. guttapila D.C.Thomas & Ardi (Thomas et al. 2009: 234) has fruits with weakly developed wings and a relatively thick pericarp; and B. comestibilis and B. torajana D.C.Thomas & Ardi ( Thomas et al. 2011: 246) show indehiscent, semi-fleshy fruits with conspicuously thick placenta branches. Individuals of B. comestibilis with unopened fruits that dried while remaining attached to the plants, and attached dried fruits with parts broken off were observed in the field (see also Ardi 361), but the exact mode of dispersal remains unknown.

Provisional IUCN conservation assessment:— Vulnerable (VU) B2ab(iii). This species was originally described from only two collections from the Lompobatang Mountains in South Sulawesi ( Thomas et al. 2011), but there have been several additional collections and observations including material from West and Central Sulawesi since then. This indicates that B. comestibilis may be fairly widespread in lowland to upland forests on Sulawesi (see Fig. 1C ), but additional collection efforts are needed to confirm this. None of the collections are from legally protected areas, and most are from forest margins or roadsides in habitats showing considerable anthropogenic disturbance. Given the poor state and severe reduction of lowland and hill forest in South, West and Central Sulawesi (Cannon et al. 2005, 2007), as well as the limited number of collections and the apparently fragmented distribution, we evaluate this species as Vulnerable.

Additional specimens examined:— INDONESIA. Sulawesi. Central Sulawesi: Parigi-Poso Road , 15 Feb. 2019, W.H. Ardi 432 . West Sulawesi: Mamasa, Gandang Dewata Mts, Tondok Bakaru village , 8 Nov. 2019, Meyga 001 (THBB: Herbarium Hortus Botanicus Baliense) . South Sulawesi: Lombasang , 20 April 1921, Bunnemeijer 11129 ( BO, K) ; Malino , 10 Oct. 1931, A. Rant 421 ( BO) ; Katemujotup waterfall, 11 Apr. 2009, D.C. Thomas & W.H. Ardi 09-62 ( BO, E, L) ; Baranging, Maroangin Karst , 10 Nov. 2018, W.H. Ardi 356 ( BO, KRB, SING) [ aff. comestibilis ] ; Air terjun Ketemu Jodoh , 10 Nov. 2018, W.H. Ardi 361 ( BO, KRB, SING) ; Poros Malino Sinjai , 14 Nov. 2018, W.H. Ardi 363, 364, 365, and 367 ( BO, KRB, SING) .

Figures

FIGURE 1. Distribution maps of Begonia species occurring on the southwestern arm of Sulawesi or the Selayar Islands (georeferenced specimen data from major collections [B, BO, E, K, KRB, L, SING], the Begonia Resource Center [Hughes et al. 2015a], as well as some additional confirmed observations). Grey lines indicate 1° graticules.

FIGURE 2. Begonia comestibilis. A: Habit. B: Ad- and abaxial leaf surface; inflorescence; scale bar = 5 cm. C: Stipule; scale bar = 8 mm. D: Male flowers, front view; scale bar = 10 mm. E: Female flower, front view; scale bar = 14 mm. F: Female inflorescence; female flower, side view; scale bar = 14 mm. G: Infructescence; scale bar = 20 mm. H: Ovary cross-section, bilamellate placentation, scale bar = 3 mm. A-H: W.H. Ardi 361. Photos: A, B, D-H: W.H.Ardi; C: D.C. Thomas.