Vachellia collinsii is widely found in drier parts of the Northwest (Guanacaste province). It can be distinguished from the related V. cornigera by the gland on the petiole and the fruit. I found plants, which were up to 7m high, mostly poorly branched, with many thickened stipular thorns, always inhabited by ants. The ants are numerous, black or brown, and frequently seen at the glands. They bite you as soon as you grab a leaf, e.g. to take a better photo or to look for inflorescences.
The thorns appear even more ferocious on dead branches.
The leaves show 2-4- small glands at the bottom of the petiole and no glands between the pinnae on the rachis. Younger leaves may still carry the Beltian bodies - before the ants harvest them. Leaves feature up to eight pair of pinnae and e.g. 22 leaflet pairs per feather. The petiole is short (1,5 cm), the rachis is channeled and appr. 10 cm long. There is a small mucro at the leaf tip. Also the single feathers had little mucros. On one specimen there was only one leaflet at the place of the first pair of leaflets on all feathers.
The following pictures were all taken in Guanacaste province in November 2008
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