Thank you to lorax aka Elizabeth of Ecuador who contributed today's photograph via the UBC Botanical Garden forums in this thread. Do drop by her weblog, I Speak for the Trees, as well -- here's her posting about this species: Anadenanthera colubrina.

Elizabeth also shared this bit of text with the image on the forums:

"Anadenanthera colubrina, commonly called huilco in Ecuador. This is a picture of a young tree, from the Imbabura province which is not part of its current typical range. However, there is a native-tree reforestation effort underway across the province which has reintroduced the huilco. In ideal conditions, this tree will grow more than 1 metre each year until it reaches a mature height of about 20 metres."

"Huilco, which are members of the Mimosoideae tribe of the Fabaceae, are closely related to Acacia, although they lack any substantial thorns on their branches. Mature trees develop broad thorns on the trunk, similar to ceibo. Like most of the Mimosoideae, the leaflets fold together at night. The huilco's range is from Ecuador south through Peru, Bolivia, Chile, Argentina, Paraguay and Uruguay, and Brazil, but its value as a timber tree has caused it to become rare or threatened throughout much of its range. It is one of the few woods available in South America that is termite resistant. It is also a useful tree to the tanning industry, as the bark is very high in tannins and can be used as part of a natural or traditional tanning process."

And I'll add that Anadenanthera colubrina has been used entheogenically (i.e., it's a psychoactive used in religious ceremonies) -- Elizabeth mentions that in the posting on her weblog.

Photography resource link: I was visiting the bookstore of the Palacio de Bellas Artes in Mexico City with the intent of discovering photographers new to me. I came across one of Yampolsky's books, Formas de Vida (Forms of Life), resting atop a section of books that had nothing to do with photography and was quite pleased to find it (I struck out in the photography section). Formas de Vida explores the contemporary cultural uses of plants in Mexico. A few of the photographs in Yampolsky's exhibit titled Evocations (from that page: (English->) Exhibitions -> Evocations -> to visit Exhibition) help give a taste of what can be found in Formas de Vida -- if the topic intrigues you, I'd highly recommend tracking down the book.