Begonia x langcangensis S.H.Huang

Tian, Dai-Ke, Xiao, Yan, Li, Yan-Ci & Yan, Ke-Jian, 2020, Several new records, synonyms, and hybrid-origin of Chinese begonias, PhytoKeys 153, pp. 13-35 : 13

Begonia x langcangensis S.H.Huang Fig. 11A, B

- Begonia langcangensis S.H.Huang, Acta Bot. Yunnanica 21:13, 1999; S.H. Huang & Y.M. Shui in C.Y. Wu (ed.), Fl Yunnan 12: 230, 2006; T.C. Ku et al. in C.Y. Wu & P.H. Raven (eds), Fl. China 13: 181, 2007.

Note.

Begonia langcangensis was described and published in 1999 and its type collection was made from Fazhan He of Lancang County in Yunnan Province. Since then, no additional specimens have been collected. During our field surveys in 2010 and 2017, respectively, we did not find any plants of this taxon in the type locality and only observed B. acetosella Craib ( Craib 1912: 347) (Fig. 11C, D ), B. handelii Irmsch. ( Irmscher 1921) (Fig. 11E, F ) and B. palmata D.Don ( Don 1825). Based on the intermediate morphology of B. langcangensis and the overlapping distributions of B. acetosella and B. handelii , it is hypothesised that B. langcangensis is very likely a natural hybrid of these two species. To further investigate this, by artificially crossing B. acetosella and B. handelii , we produced, at Kunming Botanical Garden, a hybrid that was morphologically almost the same as B. langcangensis (Fig. 11A, B ). Therefore, we confirmed that B. langcangensis is a natural hybrid. It is very similar to the hybrid (unpublished) in the same section of B. acetosella × B. silletensis subsp. mengyanensis Tebbitt & K.Y.Guan ( Tebbitt and Guan 2002), which has hairy stems and petioles and larger leaves ( Tian et al. 2017).

Distribution and phenology.

China: Yunnan, Lancang, only seen in type locality, alt. 1600 m; Laos: Luang Namtha Province, Nam Ha National Biodiversity Conservation Area, Near Na Lun Village, alt. 687 m ( Ding et al. 2020). Flowering March to May, fruiting April to July.

Conservation status.

Regionally Extinct (RE). The living plants of Begonia × lancangensis have not been found in the type locality during field surveys after its first description. Recently, however, other researchers found wild plants in Laos ( Ding et al. 2020).

Remarks.

Like B. acetosella , B. handelii and B. silletensis C.B.Clarke ( Clarke 1879), dioecious Begonia × lancangensis has berry-like fruits and was previously classified in section Sphenanthera , but has recently been integrated into section Platycentrum ( Moonlight et al. 2018). In the wild, B. acetosella , B. handelii and B. silletensis often have overlapping distributions, meaning natural cross fertilisation is possible due to their overlapping flowering periods. The hybrid plants are usually very few and, therefore, rarely observed, due to a low chance of a natural cross. Natural crossings may generate new hybrids in the future.

Figures

Figure 11. Begonia x lancangensis and its parents (B. acetosella and B. handelii) (Photos by Daike Tian) A, B male plant and female flower of B. x lancangensis C, D plant and fruits of B. acetosella E, F male and female flowering plants of B. handelii.