Plant story - Paraisometrum mileense, an "extinct" plant rediscovered

Paraisometrum mileense, a species in the family Gesneriaceae, was described in 1998 by Prof. Wen-Tsai Wang, a Gesneriaceae expert from the Institute of Botany in Beijing, part of the Chinese Academy of Sciences (CAS), during work for the Flora of China. Wang noticed that one Gesneriad specimen, collected by a French missionary, F. Ducloux, from southeastern Yunnan in 1906, was very distinctive with regard to the corolla lobes, the arrangement of the stamens in the corolla tube and the stigma number. In his publication in 1998, Wang described the new genus Paraisometrum with a single species, Paraisometrum mileense, which is endemic to China and distributed only in southeastern Yunnan. The original specimen from 1906, conserved in the Muséum National d'Histoire Naturelle, Paris was the only evidence of P. mileense.

Birds-eye view of the topography and vegetation in Shilin county (Photo: Jie Cai)

Rediscovered on a routine seed-collecting trip

In the summer of 2006, Dr Shui Yuming and students from the Kunming Institute of Botany, CAS, rediscovered P. mileense in Shilin county, in southeastern Yunnan, during a seed collecting trip. They found about 320 individuals of P. mileense in this wild population, ca. 30% of them in flower. It was the first time since Ducloux's 1906 expedition that P. mileense had been seen in the wild.
Like most of the Gesneriads, P. mileense is a limestone-loving plant and inhabits only nutrition-poor and vulnerable limestone habitats. The only known population is close to local settlements in the region and easily accessible from these villages; the habitat of P. mileense is seriously threatened by human activity.

Hope for the future

It is greatly encouraging for botanists and conservationists to rediscover a species known only from a dried herbarium specimen and thought to be extinct in the wild. Dr Shui emphasises that the rediscovery of P. mileense provided people with an opportunity to understand its evolution, conservation, and potential utilisation. Shui and his team are regularly going back to the limestone area in southeastern Yunnan to continue their unfinished work and are searching for other populations. Seeds have been collected and are kept in the Germplasm Bank of Wild Species in Kunming for long-term conservation, seed biology research and other studies. Small living collections will also be introduced to the Kunming Botanic Garden in order to enhance public education and awareness.

Story by Jie Cai, Kunming Institute of Botany, China. 2006 | More plant stories

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