This is a solitary palm with a tall, robust gray trunk that often displays prominent ring scars and a slightly swollen appearance near the base. Its smooth green crownshaft is well-developed and supports a dense crown of massive, arching pinnate leaves with broad leaflets that give the palm a bold tropical appearance. The foliage is typically deep green above with a lighter underside, while the petioles and leaf bases are thick and heavily built to support the enormous canopy. Branched inflorescences emerge beneath the crownshaft and produce rounded fruits that ripen from green to dark purplish-black. Native to humid montane regions of northwestern South America, this species is especially admired for its dramatic proportions and highly ornamental crown. The species was named in honor of the French naturalist Jean-Baptiste Lamarck, one of the early pioneers in biological classification and evolutionary thought.