Holcoglossum pumilum

Happy New Year!  I was a bit busy, and didn't manage to update this blog for a while.

The species is endemic to north and central Taiwan (Lin 1975, Wu et al. 2010).  Su (1975) mentioned that it is usually found on branches of Quercus spp (oaks). In nature, it flowers in December to February (Flora of China), which matches with the flowering time under my cultivation. The illustration is available here.  The elevation range is 1000-2000m (Flora of China), 1500-2000m (Su 1975), 1500-2300m (Lin 1975, Wu et al. 2010).  Accordingly, it has been growing well under a cool-end of intermediate temperature; the max/min daily temperature is 29/18C (84/65F) in the summer and 21/13C (70/55F) in the winter.  I am growing it under a moderate amount of light (180-190 µmol/m^2/s with Apogee SQ-520 quantum sensor).  My plant originally came from Andy's Orchids as Ascocentrum pumilum.  It is a lovely miniature species with the leaf length of about 4-5cm.

This species was originally described as Saccolabium pumilum, and it was transferred to genera Ascocentrum and Ascolabium at some points. A recent study shows that it actually belongs to Holcoglossum (Xian et al. 2012, Zhang et al 2013).  The typical flowers of Holcoglossum is white, but 3 species with colorful flowers were misplaced in different genera, and this species is one of them (Xiang et al. 2012). The other two misplaced species, Penkimia nagalandensis (yellow flower) and Ascocentrum himalaicum (pink flower), are now transferred to Holcoglossum.  Interestingly, molecular phylogeny showed that pink flowers of H. pumilum and H. himalaicum are independent origin (Xaing et al. 2012), suggesting that flower colors (which can influence pollinator types) can rapidly evolve.

Literature Cited:

• Lin, T. P. 1975. Native Orchids of Taiwan. Volume 1, Orchids Orient, Taipei, Taiwan. p.36-37
• Su, H. J. 1975. Native Orchids of Taiwan, 2nd Edition.  Harvest Farm Magazine, Taipei, Taiwan.  p.82
• Wu, R. Y., Hsieh, T. F., Dai, T. E., Lai, Y. H., & Ho, C. J.  2010. Collection, Conservation and Utilization of Taiwan Native Orchid Germplasm. In M.G. Blanchard et al. (eds) Proceedings of the First International Orchid Symposium 878: 29-36. (link)
• Xiang, X., Li, D., Jin, X., Hu, H., Zhou, H., Jin, W., & Lai, Y. 2012. Monophyly or paraphyly–the taxonomy of Holcoglossum (Aeridinae: Orchidaceae). PLoS one, 7(12), e52050. (link)
• Zhang, G. Q., Liu, K. W., Chen, L. J., Xiao, X. J., Zhai, J. W., Li, L. Q., Cai, J., Hsiao, Y. Y., Rao, W. H., Huang, J., Ma, X. Y., Chung, S. W., Huang, L. Q., Tsai, W. C., Liu, Z. J. 2013. A new molecular phylogeny and a new genus, Pendulorchis, of the Aerides–Vanda alliance (Orchidaceae: Epidendroideae). PLoS One, 8(4), e60097. (link)