Of the 12 Poaceae subfamilies, Bambusoideae is one of the largest and currently includes 115 genera with1439 described species. The diversity of woody bamboos in Yunnan Province, southwestern China, is one of the highest in the world, both at the community and species levels. Fossil evidence can provide new insights into the phylogeny and biogeography of Bambusoideae, but reliable fossil records of Bambusoideae are rare, especially in China despite their modern-day species richness and wide distribution. It is not clear whether the prevalence of extant Chinese bamboos corresponds to a recent diversification event or whether bamboos have been present in China for a long time but without a clear fossil record.
Prof. ZHOU Zhekun of Xishuangbanna Tropical Botanical Garden (XTBG) and his team discovered numerous well-preserved leaf blades and culms from the middle Miocene deposits in Sanzhangtian Basin, Zhenyuan County, Yunnan, Southwestern China (24°06' N, 101°13' E). Based on forty-four well-preserved compression and impression fossil leaf blades, they described the fossil bamboo species. The materials represented the earliest bamboo fossil blades and culms from China, with detailed external morphologies.
Based on the lack of morphological and anatomical similarities with other fossil and extant culms, the researchers placed the fossil culms from Sanzhangtian into a new genus Bambusiculmus. The researchers also proposed four new species: Bambusium angustifolia L. Wang et Z.K. Zhou, sp. nov. , Bambusium latifolia L. Wang et Z.K. Zhou, sp. nov., Bambusiculmus latus L. Wang et Z.K. Zhou, sp. nov., Bambusiculmus angustus L. Wang et Z.K. Zhou, sp. nov..All fossil materials and epidermis slides are kept in Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences.
Their findings provided the earliest evidence of bamboo fossil leaf blades and culms in China. The presence of bamboo fossils in Sanzhangtian indicated that bamboos had occurred in Yunnan over a long geological history; a diversified fossil bamboo forest or bamboo understory was already present during the middle Miocene in Yunnan, the biodiversity center of modern bamboos in China. The study entitled “The earliest fossil bamboos of China (middle Miocene, Yunnan) and their biogeographical importance” has been published online in Review of Palaeobotany and Palynology