Family: Cyperaceae

Puʻukaʻa is not native to Hawaiʻi Island, but is endemic elsewhere in the Hawaiian Islands. It is a green clumping sedge that can reach up to 2.5 feet and spreads up to 12 inches. Leaves range from 6-18 inches long, feel leathery, and have a sticky waxy coating. The hotter the conditions, the stickier the leaves seem to get. This sedge is perennial and produces 10-30 pale yellowish spikelets that radiate out, each containing 8-20 flowers. The fruits are dark brown, egg-shaped achenes. Cyperus trachysanthos is distinguished from others in the same genus by its short rhizome (leaf sheath with nodal partitions), egg-shaped glumes (pair of bracts at spikelet base), and 8-18 inch culms (aerial stems). Of the 14 species of native Cyperus sedges in Hawaiʻi, puʻukaʻa is currently the rarest.

Habitat & Uses

Puʻukaʻa is an endangered sedge known to be found in wet habitats ranging from zero to 1000 feet in elevation. Natural populations can now only be found on Oʻahu, Kauaʻi, and Niʻihau with historic populations occurring on Molokaʻi and Lānaʻi. It is known to grow along the margins of ponds, wet slopes, mudflats, coastal cliffs, and wet clay soil. If found in drier regions, these areas must be moist to flooded during the wet season. On Kauaʻi, you can find puʻukaʻa growing amongst hau (Hibiscus tiliaceus), narrow-leaved plantain, and Chinese brake. This rare sedge is at more extinction risk due to browsing by feral goats and resource competition with invasive plants.

There are not too many noted uses for puʻukaʻa today, which may be due to its difficulty to find or access. Historically, this sedge could be stewed until completely cooked and then used in bathing until the very small and fine lumps or puʻu fall off. Formerly, when ʻahuʻawa was not available, the fibers of this sedge were used for straining ʻawa. The attractive flowering spikes of puʻukaʻa could be used in cut flower arrangements or within haku and wili style lei.

Landscaping & Cultivation

Puʻukaʻa is a federally listed endangered species, which can make them harder to find in cultivation. However when you find them, puʻukaʻa can be versatile in the landscape.  This sedge can tolerate drier conditions, but need primarily wet to moist soils or at least seasonal flooding. To grow to its fullest potential, place in full sun and protect from wind. You can place puʻukaʻa in or around water features or try it as a low-maintenance addition to your Japanese-style gardens with river rock or black cinder. Its bright green and “bursting” nature looks great as an accent against rock features or amongst groundcover plants.

Puʻukaʻa is a great native alternative for the commonly used and invasive umbrella sedge. Few pests bother this plant, but you can occasionally find aphids on new shoots as well as ants, scales, mealy bugs, and root mealy bugs. Occasional pruning of dead leaves will keep the plant looking full and beautiful. Otherwise maintenance is minimal as long as there’s enough soil moisture. Additionally, you may not want to grow puʻukaʻa in a well-visited area as the leaf blades are so slender that once bent they won’t perk back up.

Name Origins

The ʻŌlelo Hawaiʻi puʻukaʻa is from Niʻihau and is now the name used most locally. The name puʻukaʻa is also shared with another native rare indigenous sedge, the fragrant flatsedge (Cyperus odoratus). The Hawaiian name can have many meanings, puʻu can refer to any protuberance from the scale of a pimple to a big hill and kaʻa can mean to roll, turn, twist, or wallow. So together, the name puʻukaʻa could be referring to its traditional use in bathing and straining ʻawa. The scientific name cyperus is Greek for sedge and the Greek trachysanthos can be broken down to “shaggy or rough flowered.”

Plant Uses:

• Aquatic plant
• Container plant
• Cultural significance
• Cut flower
• Erosion control
• Lei flower
• Specimen

Plant Dangers:

• No dangers