Ramosmania Rodriguesi

''Ramosmania rodriguesi'', commonly known as café marron, is a tree native to the Mauritian island of Rodrigues in the Indian Ocean. The plant has an average size of about and features white five-petal star-shaped flowers. Its French common name translates to "brown coffee."

History

It was thought ''Ramosmania rodriguesi'' was extinct until a single surviving tree was spotted by a schoolboy in 1979,Smith, P. (2023, June 1). The loneliest tree in the world. Botanic Gardens Conservation International. Retrieved June 30, 2023, from https://www.bgci.org/news-events/the-loneliest-tree-in-the-world/ who was shown a drawing of the plant by his teacher. The only image of the plant was made in 1877, by a European visitor, passing through Rodrigues. By the 1950s, it was presumed to be extinct. In the 1970s, a specimen was discovered; cuttings were taken to Kew Gardens, and although the plant regularly flowered, it never produced seed until horticulturist Carlos Magdalena discovered how to make the male plant bear female flowers.

''Ramosmania rodriguesi'' was assessed as a Critically Endangered species in 1998.

In 2003, the café marron bore its first fruit with viable seeds. Slow but steady efforts have been made to grow more café marron trees and speed up the pollination process.

In 2010, there were 300 successfully germinated seeds in Rodrigues, spreading hope that the species can eventually exist in the wild once again.Magdalena, C. (2010) ''Raising the living dead:'' Ramosmania rodriguesii. Sibbaldia 8, p.63-73 http://www.botanicgardens.eu/downloads/sibbaldia8.pdf

Taxonomy

''R. rodriguesi'' is in the same Rubiaceae family as the now extinct ''R. heterophylla'' which used to reside on Rodrigues. D.D. Tirvengadum originally thought that ''R. heterophylla'' and ''R. rodriguesi'' were the same species, until he noted that the shape of the ''R. rodriguesi'' leaves were "elliptic obtuse" in comparison to those of ''R. heterophylla''.

Life cycle

Moths pollinate the plant while Rodrigues flying foxes spread the seeds. These pollinators are less endangered than ''R. rodriguesi'', therefore their absence is not expected to be a problem when the species is reintroduced to Rodrigues. ''R. rodriguesi'''s female flowers develop after male flowers, indicating that the plant is protandrous. The appearances of the young plant and its adult counterpart are drastically different, likely meant to deter predators from eating the young plant before it matures and reproduces. The species is also heterophyllous, meaning that they have both young leaves growing at the bottom of the plant while there are adult leaves on the top half of the plant.

Appearance

Young ''R. rodriguesi'' leaves have obtuse, rounded apexes while mature leaves have rounded, almost truncated apexes. The petals' tube is funnel-shaped and leathery with a length of 1 centimeter. The plant's fruit is thin and elongated. Additionally, ''R. rodriguesi'' have smooth midribs as opposed to their hairy counterpart, ''R. heterophylla.''

Cytology

The diploid chromosome count is 2n = 22.Kiehn, M., & Berger, A. (2023)
"New chromosome counts on Rubiaceae from Africa and the Western Indian Ocean islands."
Nordic Journal of Botany, e03732.

Threats

The species' most prevalent threats are predators, poaching, pests, and habitat loss. Giant tortoises are ''R. rodriguesi'''s primary predator and they feast on young, low-hanging leaves. Researchers hypothesized that in response to the predation of giant tortoises, the species' young leaves evolved to appear darker and therefore less appealing or visible to the tortoises. Other notable predators are the dodo-descendant, Rodrigues solitaire, and goats. Poaching is also extremely damaging to the species. The urban legend associated with the plant contributed significantly to the amount of poaching because people wanted to use the plant to cure their hangovers and liver diseases. Mealybugs are known pests for ''R. rodriguesi'' and they do not harm the plant unless they become infested, which disrupts development.

Conditions

''R. rodriguesi'' can only survive in tropical temperatures of 19-23 °C with 70-80% humidity. The plants do not have a preference for shade or light, though flowering occurs more so when shaded.

Urban legend

Many locals of Rodrigues subscribed to the belief that ''R. rodriguesi'' had the potential to remedy venereal diseases and cure hangovers. This is how the plant gained its nickname, . Subsequently, many people cut pieces from the plant and inhibited its further cultivation, which turned out to be a considerable factor in the species' endangerment.

References

Ramosmania rodriguesii

External links

Kew Gardens: Cafe marron

Octotropideae
Critically endangered plants
Endemic flora of Rodrigues
Plants described in 1989
Taxobox binomials not recognized by IUCN

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