Mystery Tree of Rondônia

By Douglas C. Daly

May 14 2020

In September 2019 I went to Rondônia state in Brazil in the aftermath of last year’s horrific, purposely set forest fires in the Amazon. I was in Jacundá National Forest with a team from the university there to look in on the timber management program, and to document some of the tree flora. While we were staying at Jacundá’s field station, the manager told us of a giant mystery tree 50 feet away from the station that had stymied everyone who had studied it, including perhaps the two best wood identifiers in the Amazon. No one had been able to make a collection of the branches up in the canopy, so they were relying on characters one can access from the ground: some fallen dead leaves and pods at the base, the bark, and the slash (what the sap looks like when you cut into the bark).

Luckily our master woodsman Edilson Oliveira was able to make the climb and send down leafy branches. To our surprise, even Edilson, our field ID superstar, drew a blank on this mystery giant. So we threw the book at it – in fact, we threw several books at it, using every resource about the plants of the Amazon that could potentially solve this mystery. We consulted an old field guide to the genera of woody plants in northwestern South America, a field guide to the flora of the Reserva Ducke in central Amazonia, and an illustrated book on trees of Peru. We had sporadic internet access, so we posted our field photos of the mystery tree to several excellent “generalists” who have broad knowledge of the Neotropical flora, and we received promising on-line suggestions from Daniel Santiago, a brilliant young colleague in Costa Rica. We also had our own knowledge of the Amazon flora, backed up by the specimen images from the C. V. Starr Virtual Herbarium.

A breakthrough came from a combination of a vague recollection of mine and the old general field guide, which nailed the genus, Stryphnodendron. Surfing through the many images of the genus in the virtual herbarium, we finally put the mystery to rest: Stryphnodendron occhionianum E.M.O.Martins, a rare tree in the legume family known mostly from the other side of Amazonia on the eastern extreme, in the states of Pará and Amapá. Only one other NYBG collection of S. occhionianum was known in Rondônia before this discovery.

A Closer Look

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Gentry, A. H. 1996. A Field Guide to the Families and Genera of Woody Plants of North west South America : (Colombia, Ecuador, Peru). Chicago: The University of Chicago Press.

Martinez, R. V. 1997. Flórula de las Reservas Biológicas de Iquitos, Perú: Allpahuayo-Mishana, Explornapo Camp, Explorama Lodge. Monographs in systematic botany from the Missouri Botanical Garden, vol. 63. St. Louis: Missouri Botanical Garden Press.

Pennington, T. D. & Reynel, C. 1994. Illustrated Guide to the Trees of Peru. Sherborne, United Kingdom: David Hunt.

Ribeiro, J. E. 1999. Flora da Reserva Ducke: Guia de identificação das plantas vasculares de uma floresta de terra-firme na Amazônia Central. Manaus: INPA/DFID.