Volume 14 > Part 3 > Year 2019 > Page 411 > Begoniaceae > Begonia

39. Begonia pteridiformis Phutthaiwfo-0000923003

[§ Lauchea], Thai Forest Bull., Bot. 38: 37. 2010. Plate XXXIX: D.

Accepted Name : This is currently accepted.

Description : Monoecious caulescent herb, 12−25 cm tall, whole plant covered with glandular hairs. Stems succulent, suberect with 2−5 branches, dark red at base, turning pale green near top; tubers irregularly heart-shaped with numerous fibrous roots, 5−13 mm diam. Leaves all in same horizontal plane, 8−30 per plant; petioles pale red, 1.5−3 mm long, with an adaxial groove; lamina basifixed, membranaceous, subsymmetric, chartaceous when dry, adaxial surface with dense glandular hairs, light green, iridescent, abaxial surface with dense glandular hairs, pale greenish white with red hyaline line along margin, narrowly lanceolate, 2−8 by 0.5−1 cm, base symmetric or subsymmetric, truncate or subcordate, apex caudate or more acuminate, margin dentate, midrib prominent beneath, hairy, lateral veins 7–8 on each side. Stipules persistent, pale green, triangular or ovate triangular, ca 1 by 1 mm, apex acuminate, margin entire, with sparse minute glandular hairs. Inflorescences terminal or at least near the apex, dichasial, bisexual, 1−3 branches, 0.5−2.5 cm long with 2−4 staminate flowers and 2 pistillate flowers per branch; protandrous; peduncle, 0.5−1 cm long, terete, pale green, hairy. Bracts deciduous, pale green, membranous, ovate-triangular, oblong, 1−2 by 0.5−1 mm, apex acute, white, margin sparsely ciliate. Staminate flowers: pedicels 5−6 mm, sparsely hairy; tepals 4, plain white, outer 2 ovate or obovate, 2 by 2−3 mm, base cuneate, apex acute, margin entire, glabrous on both sides; inner 2 oblanceolate, 2 by 1 mm, base cuneate, apex obtuse, margin entire, glabrous on both sides; androecium zygomorphic; stamens 10−12, yellow, filaments fused at base ca 0.5 mm long, anthers cordate, ca 1 mm long, dehiscing by longitudinal slits. Pistillate flowers: pedicels white, 5−6 mm long, sparsely hairy; tepals 5, unequal, oblanceolate or obovate, plain white, 2−3 by 1−2 mm, base cuneate, apex rounded, margin entire, glabrous on both sides; styles 2, fused at base, yellow, stigmatic band kidney-shaped, papillose; ovary with 3 unequal wings, plain white, 2-locular, placentae bilamellate. Fruit a dehiscent capsule, pendulous, creamy white, turning brown when dry, 15 by 10−12 mm; locules oblong, 4 by 1.5−2 mm, abaxial wing obliquely triangular, ca 3 mm long, lateral wings narrower, triangular, 1−2 mm long, ca 1/3 capsule length. Seeds brown, ellipsoid.

Thailand : PENINSULAR: Krabi, Phangnga (Nam Tok Manora Forest Park – type: Phutthal 123, holotype -BKF, isotypes -E PSU), Surat Thani.

Distribution : Endemic.

Ecology : Clinging to limestone cliffs or wet limestone rock in deeply shaded areas at ca 100 m alt. Flowering: May–November; fruiting: November–January.

Vernacular : Som kung bai foen (ส้มกุ้งใบเฟิน).

Notes: Begonia pteridiformis differs from other species in sect. Lauchea in having many (8–30) narrowly lanceolate leaves held on horizontal stems. This makes it appear, at first glance, like a pinnately compound fern leaf. The specific epithet ‘pteridiformis’ is derived from this characteristic leaf arrangement.