This small species has the stem from fifteen to twenty feet high and about two inches in diameter, with obscure rings of spines at irregular intervals. The leaves are terminal, rather large and regularly pinnate. The leaflets are narrow, rigid and scarcely drooping, with the terminal pair broader. The midrib and leaflets are smooth, but the bases and sheaths of the petioles are very prickly.

The spadices grow from below the leaves and are very small and simply branched. The spathes are small, ovate, swollen, erect, persistent and very prickly. The trees were not found in fruit.

This tree agrees pretty well with Dr. Martius’ description of A. aculeatum. It grows in the virgin forest of the Upper Rio Negro.