Rhamnaceae sp.

December 21, 2009

When I took that banking business trip last week to Entre Rios, I made a short side trip to a patch of Atlantic forest where among other I found a fallen tree (with its roots damaged by rot) of a species never seen before. I took some pictures and a couple of branches with leaves still on to study the species at home. I soon realized that it was a species of Rhamnaceae, and figured out that the only local arboreal Rhamnaceae belong to Ziziphus. I had seen a couple of other Ziziphus spp. around. One is Z. jouazeiro Mart., a tree similar in size to the newly discovered sp. The other a shrub, with numerous thorns. The latest Rhamnaceae is without thorns, and, according to Gentry’s Field Guide to the Families and Genera of Woody Plants of Northwest South America (Columbia, Ecuador, Peru), with Supplementary Notes on Herbaceous Taxa, U of Chicago P, 1996, the only Z. sp. that is thornless and fits its habitat description as that of a ‘canopy tree of  moist lowland forest’ is Z. cinnamomum. Gentry’s Guide, even though meant for western Amazon, is quite useful as an aid in identifying species (at least to genera) when sterile (=without flowers, or fruit). I wonder if it’s my sp. Checklist das Plantas do Nordeste Brasileiro (Checklist of Plants of the Brazilian Northeast) has it listed but the speciesLink (the online Brazilian herbaria database http://splink.cria.org.br/centralized_search) has it only for the states of Acre, Maranhão, and Pará.

I have contacted a Brazilian specialist in Rhamnaceae and am awaiting her response.

An image of its leaf underside, with typical Rhamnaceous venation follows. The rest of the images are on Flickr (http://www.flickr.com/photos/plants_of_russian_in_brazil/sets/72157622920308729/).

Leaf underside.

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