Begonia melanobullata

Taxonomy

- Genus: Begonia - Species Cultivar: B. melanobullata - Author: C.-I Peng & C. W. Lin (Botanical Studies 2015, 56:9) - Publication Date: 2015 - Date of Origin: 2010 - Place: Cao Bang Province, Thach An District, N Vietnam - Habitat: Found on semi-shaded wet cliffs or steep limestone slopes in evergreen broad-leaved forests, at an elevation of 300–400 m.

Region

- Asia

Section

- Section: Coelocentrum

Genetics

- Chromosome Number: 2n = 30

Plant Type

Rhizomatous

Etymology

The specific name is derived from Latin words, melano (very dark) and bulla (bubble or blister), referring to the leaf surface.

References

- Ching-I Peng, Che-Wei Lin, Hsun-An Yang, Yoshiko Kono and Hieu Quang Nguyen. "Six new species of Begonia (Begoniaceae) from limestone areas in Northern Vietnam." Botanical Studies 2015, 56:9. - Hughes M. et al. "Asian Begonia 203, 2018."

Photos

Classification and Origin

This plant is allied with B. ferox. It is found in Vietnam, specifically in Cao Bang Province, Thach An District. The type specimens were collected on June 29, 2010, and additional specimens were cultivated in Taiwan.

Characteristics

Begonia melanobullata is a perennial, rhizomatous herb. It has a stout, creeping rhizome that can grow up to 50 cm long and 1-2.5 cm thick. The stipules are yellowish to pale green, ovate-triangular, and have a keeled shape. The leaves are alternate, widely ovate to elliptic, with unique features like bullae (small raised structures) on the upper leaf surface. The inflorescences emerge directly from the rhizome, forming branched dichasial cymes. The plant exhibits both staminate (male) and pistillate (female) flowers.

Flower Details

The staminate flowers have 4 tepals, with the outer 2 being broadly ovate and the inner 2 being elliptic. There are around 65-80 stamens with yellowish-green to gold yellow anthers. The pistillate flowers have 3 tepals, and the ovary is trigonous-ellipsoid with wings. The styles are fused at the base and form a twisted stigma. The capsule is also trigonous-ellipsoid with wings.

Distribution and Habitat

This species is endemic to Thach An District, Cao Bang Province, Vietnam, close to the border with China. It grows in semi-shaded wet cliffs or steep limestone slopes within evergreen broad-leaved forests. Its elevation ranges from 300 to 400 meters.

Etymology

The specific name "melanobullata" refers to the dark maroon bullae on the leaf surface.

Comparison to Similar Species

Begonia melanobullata is similar to B. ferox and B. nahangensis in having dark bullae on the leaf upper surface. However, it is distinct due to its ovate to elliptic leaf shape, longer peduncle, more branched inflorescence, and different flower characteristics. Detailed comparisons with B. ferox and B. nahangensis are provided, highlighting differences in leaf shape, flower color, and other features.

Endnote

Begonia melanobullata is unique to the limestone areas of Cao Bang Province and has specific differentiating features from similar species.