Rare species of Rhododendron rediscovered in Bhutan after 84 years

The Flora of Bhutan describes a total of 46 species out of which 45 are known to be occurring in Bhutan. The book describes Rhododendron pogonophyllum as a rare endemic plant to Bhutan. Subsequent publication of the book “Plants Endemic to Bhutan Himalaya” by the National Biodiversity Centre (NBC) published in 2015 listed it as one of the endemic plant species found in the country with a herbarium specimen as an evidence. “Wild Rhododendrons of Bhutan”, a book by Rebecca Pradhan in 1999 has photos of the Rhododendrons found in Bhutan including R. pogonophyllum with descriptions of its flower, leaf, flowering time, habitat, altitude, distribution and with a remark stating as an endemic and rare plant species not seen since 1937,  but without any picture. The book reports a total of 46 Rhododendron species in Bhutan.

Rhododendron pogonophyllum flowering in its natural habitat

  1. pogonophyllum was first collected by George Sherriff, a Scottish plant collector on 7 June 1937 at Tang Chu in Wangdue. His 1937 trip was mainly focused around the central Bhutanese mountains including the Black Mountains. He ventured out to explore the Pele La range which falls to the east of Dangchu which Sherriff wrote as Tangchu in his specimen locations. After a night halt at Trashidinkha in Dangchu, he climbed towards Kyitsugang which Sherriff wrote as Chizukang. On his second day, he found many interesting plants including Primulas and the Rhododendron pogonophyllum in particular under the collection number 3216. Earlier the specimen collected was thought to be Rhododendron hypenanthum which is now considered as a subspecies of Rhododendron anthopogon. Later Cowan & Davidian described it as a new species using the specimen collected by Sherriff from this locality and the specimen currently resides at Royal Botanic Garden Edinburgh in UK with the catalogue number E00010309. Later in July Sheriff also collected the same Rhododendron species from Rinchen Chu (Chore) in central Bhutan on 13 July 1937. Currently, Chore is known as Khero to the locals and the present day Nikachu was known as Rinchenchu. Chore=Khero and Chizukang=Kyitsugang lie on the same mountain range separating the Nikachu and the Dangchu watersheds. Khero [Chore] is located within the aerial radius of around 5 km from Kyitsugang [Chizukang].

With the help of David Long from the Royal Botanic Garden Edinburgh and Pam Eveleigh from the Primula World, the type locality was traced and a team from the National Herbarium and Royal Botanical Garden, Serbithang under NBC made an expedition to the mountain east of Dangchu in June this year. During the expedition, the team was faced by incessant rainfall and footpath which was barely noticeable since the cow herders of the Ramno grazing area stopped taking their cattle to the grazing area last year. The team took shelter in the wooden huts of the cow herders from Dangchu and ascended through steep cliffs towards the Kyitsugang the next day.

The habitat of Rhododendron pogonophyllum at Kyitsugang in Dangchu, Wangdue Phodrang. The whitish specks visible on the cliff side of the mountain is the R. pogonophyllum.

Despite the incessant rainfall and cold mountain winds, the team finally found the lovely and tiny Rhododendron pogonophyllum flowering beautifully and precariously on the rocks and rocky soils on open hillsides at Kyitsugang at an altitude of 4452 masl. Kyitsugang is considered by the residents of Dangchu to be the abode of their deity Kyitsub. Rhododendron pogonophyllum which was recorded in 1937 is thus rediscovered after 84 years in Bhutan. The specimens collected will be deposited in the National Herbarium of Bhutan (THIM) which is the official botanical repository and reference centre of the country.

Rhododendron pogonophyllum Cowan & Davidian is a creeping subshrub which has similar flowers to that of Rhododendron anthopogon with small obovate leaves with rounded or retuse apex, rounded at base and scaly leaf underside.

-NBC

 

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