Native Hawaiian Garden (7722) - Mau‘u ‘aki‘aki

Mau‘u ‘aki‘aki (Fimbristylis cymosa) – Weeds in the nursery

Very few native Hawaiian plants might be considered weeds. I know of only one, ‘uhaloa (Waltheria indica), referred to as a “weed in cultivated areas and waste places” in the Handbook of Hawaiian Weeds (2nd Edition, 1983). Undoubtedly, in ancient times, Hawaiians had to deal with numerous native weeds in their lo‘i and māla – can you imagine a Hawaiian pulling out handfuls of the today endangered pu‘uka‘a (Cyperus trachysanthos) and tossing them onto the banks of his lo‘i to rot! Much more common are native Hawaiian plants that become weeds within the ideal environmental conditions of the nursery. Mau‘u ‘aki‘aki is one such native nursery weed, with seedlings randomly and often abundantly sprouting in the pots of other nursery plants or beneath the nursery benches in those nurseries with a gravel or dirt floor. (In the Wai‘anae High School Nursery I help manage, mau‘u ‘aki‘aki seedlings appear in the cracks of the nursery’s concrete floor and immediately outside in a border garden.) More amazing are the rare and endangered Hawaiian plants that become weeds in the nursery. For example, the ‘Ewa Plains ‘akoko is very easy to propagate and grow. Whenever I let one or more of these ‘akoko mature in the nursery, seedlings soon begin showing up in the pots of other nursery plants nearby. Likewise, my good friend, Anna Palomino, who manages the State’s Olinda Rare Plant Nursery on Maui, tells me it’s not uncommon for her to discover tiny new endangered ferns, mints, and other rare plants popping up in the pots of nearby unrelated plants. Clearly, Hawai‘i’s environment is a much tougher place today, a place where once native weeds are today nearly extinct.

Habitat & Appearance: Mau‘u ‘aki‘aki is common in both sandy and rocky coastal areas across the Pacific including Australia, west Malesia, and the Neotropics. In Hawai‘i, it is found on Midway, Kure, Laysan, French Frigate Shoals, and all the main islands except Kaho‘olawe. This compact sedge, depending on the habitat, can be anywhere from a few inches across and tall to nearly a foot wide. The leaves are stiff and pointed. Multiple flowering spikes grow out above the main plant producing a terminal cluster of fruits that are rusty brown when ripe. Achenes are extremely small (1 mm) and numerous. There are two subspecies: subsp. spathacea have an open inflorescence with multiple heads while subsp. umbellato-capitata often has a single compact head. However, plants with inflorescence characteristics intermediate between the two subspecies have also been discovered.

Mau‘u ‘aki‘aki achenes (seeds). One-week-old seedlings. Three-month-old plants. Header photograph courtesy of cicy.mx ©.

Mau‘u ‘aki‘aki in Hawaiian Culture: I could not find any recorded Hawaiian uses or mo‘olelo (stories) associated with this plant.

Collecting Seeds: Wait until the fruiting-head is rusty or grayish brown before collecting. I simply grind the ripe head between my fingers above an open paper envelope to store the achenes in my refrigerator or directly over a pot of wet clean media for direct sowing.

Growing from Seed: I do not try to sow mau‘u ‘aki‘aki seeds individually because they are so tiny. Rather, I grind a ripe fruiting-head directly above a small pot of clean media (usually a 1:1:1 mix of peat moss, perlite, black cinder) and gently water to embed the seeds in the media. In less than a week, you’ll see tiny seedlings sprouting like a field of grass in the pot (see photograph to right). Wait two to three weeks until the seedlings are about one inch tall. Then, submerge the pot in a basin of water, separate the pot from the seedlings and media, and gently separate and repot each seedling in its own pot. The individual seedlings grow rapidly, even more so with a little controlled-release fertilizer. Within two months, they will be approximately 2 to 3 inches wide and tall; they may also begin flowering and fruiting at this age. You should then transplant them into your garden.

Growing by Division: A common propagation method for mau‘u ‘aki‘aki is division. Once a plant gets large, simply remove it from its pot or the ground, cut it into two or more smaller plants with a knife (or break it apart by hand), and repot or replant the new plants. Be certain to water heavily after the division until the roots recover (in about a week).

Growth in the Garden: Mau‘u ‘aki‘aki grow best in full sun. And, most varieties, once established, prefer infrequent watering (once a month or less). However, some varieties are best adapted to more frequent watering (once a week). Therefore, you’ll have to do a bit of experimenting to find the best watering schedule for your plant(s); the leaves of underwatered plants tend to turn brown and die while the leaves of overwatered plants tend to turn yellow. Some gardeners prefer to plant many mau‘u ‘aki‘aki close together to create a continuous groundcover. Recently, investigators such as University of Hawai‘i Joe DeFrank and Orville Baldos have been experimenting to determine mau‘u ‘aki‘aki potential as a highway landscape plant. You can check out their demonstration planting off Interstate H1 at the University Avenue interchange on O‘ahu. A rumor I’ve heard but never tested is the spiky leaves of many mau‘u ‘aki‘aki planted as a continuous groundcover will keep cats out of your garden.

Diseases & Pests: The only pests I’ve ever encountered on mau‘u ‘aki‘aki are scale insects. Refer to Enemies in the Garden for ways to eliminate scale.

Ā ā Ē ē Ī ī Ō ō Ū ū