Achyranthes divaricata (synonym Nototrichium divaricatum), also known as Na Pali rockwort or kuluûë (Hawaiian), is a critically endangered perennial shrub in the pigweed family, Amaranthaceae, that is endemic to the island of Kauaûi in Hawaii. It can only be found in three valleys on the northwestern end of the island, where it grows on north-facing cliffs and ridges.
Achyranthes divaricata are densely branching shrubs that can grow up to 50 cm tall, with most parts covered with silvery-white hairs. Leaves are oppositely arranged, with leaf blades 3âÂÂ7.5 cm long and 1âÂÂ4.6 cm wide. Inflorescences bear several spikes, and are terminal and usually solitary, rarely 2 or 3 together, and compoundly branched. Each spike bears 8âÂÂ30 small flowers. There are possibly fewer than 3,000 A. divaricata plants in existence.
This species was first described as Nototrichium divaricatum by David H. Lorence in 1996. In 2024 Vanessa Di Vincenzo et al. placed the species in genus Achyranthes as A. divaricata.
This species is characterized by its bushy growth, typically reaching heights of between 0.3 and 2 meters. Achyranthes divaricata features densely hairy branches and twigs, giving them a silvery-white appearance. The leaves are arranged oppositely, and have petioles that can vary in size and shape. Each leaf measures approximately 2-7.5 cm x 0.6-4.6 cm. The plant produces unique flower clusters with multiple branches, and can contain anywhere from 4 to 66 flowers.
Achyranthes divaricata is endemic to cliffs and ridges on the northwestern end of Kaua'i, particularly in the Hanalei District and Na Pali coast. It thrives at elevations of 600 to 1100 meters in areas where remnants of lowland and montane mesic forests are still present. The primary challenges facing Achyranthes divaricata include damage and habitat loss due to the activities of feral goats, which threaten many endemic species throughout Hawai'i. Additional risks include landslides, rock falls, and non-native plants.