Showcasing Kew's Collections - passionflower (Passiflora tridactylites)

Discover the history of the discovery of passionflower (Passiflora tridactylites) and its relationship with past Directors of Kew.

Herbarium specimen of Passiflora tridactylites

Darwin, the HMS Beagle and Hooker

This specimen of passionflower (Passiflora tridactylites) is from the Herbarium collection at Kew and was collected by Charles Darwin whilst on a voyage with the HMS Beagle.

Darwin left England on the second tour of the HMS Beagle in 1831 for an expedition that would last five years. Darwin and the Beagle reached the Galapagos Islands in autumn 1835 and Darwin collected this specimen from Charles Island, now named Floreane Island, during the five weeks he spent there. It was one of two unfamiliar species of passionflower collected while the ship was in the Galapagos Islands and as Darwin was on the islands in September and October of 1835 the specimens collected were not in flower. The Passiflora tridactylites has a propensity to grow in rocky, shady areas and as a vine it climbs over the ground and over shrubs and tree trunks, these vines can be seen in the pressed specimen.

On his return to England in 1836 Darwin gave his collection of Galapagos plants to Professor John Stevens Henslow at Cambridge University for analysis. By 1843 Henslow had still not found the time to examine and report on the items collected so Darwin asked Joseph Hooker to examine the examples of flora instead. Darwin was interested in whether the plants he had collected were unique to the Galapagos Islands or whether they were also found in South America. Hooker deciphered that many of the plants collected by Darwin had close and clear links with plants in South America but out of the 217 species collected Hooker found that 109 were confined to the archipelago and 85 to a single island. Hooker believed the two examples of passionflowers collected by Darwin to be new species and gave the names Passiflora tridactylites and Passiflora puberula (now Passiflora suberosa). This association was part of a lifelong friendship between Darwin and Hooker and Darwin’s time on the Beagle and his findings in the Galapagos Islands were presented in his book On the Origin of Species.

Detail of Herbarium Specimen Painting showing the Passiflora tridactylites (© Rachel Pedder-Smith)

The Herbarium at Kew

This Passiflora tridactylites specimen was then acquisitioned in the Herbarium Hookerianum in 1867 which was William and Joseph Hooker’s private collection of preserved plant specimens. The Herbarium Hookerianum was one of many which were amalgamated to form the present day Herbarium at Kew on its foundation in 1853. Other collections combined included botanist George Bentham’s and M J Berkley’s mycological herbarium. The present day Herbarium at Kew holds eight million specimens to document the identity of plants and fungi with 37,000 specimens added to the collection annually. Once collected, specimens such as the Passiflora tridactylites are dried and pressed then attached to a sheet of cartridge paper or other archival paper and a label is placed in the bottom right corner to indicate provenance, collector, number and identity. In the Herbarium the specimens are stored by family, region, genus and species. The dried, pressed collections are supported by the carpological and spirit collections. There is a large Herbarium digitisation programme currently underway with over 500,000 specimens already available to view online.

It was the Herbarium collection at Kew which provided contemporary botanical art Rachel Pedder-Smith with material to paint from. Her painting of the Passiflora tridactylites specimen collected by Darwin can be seen as part of her exhibition The Pressed Plant - Herbarium Specimen Painting on display in the Shirley Sherwood Gallery of Botanical Art between 31 March - 7 May 2012.