Sedges have edges — did you know that? It’s how we can tell a grass from a sedge.
Years ago, when I was working at Ho‘omaluhia Botanical Garden in Kaneohe, our visionary boss Martha McDaniel got a grant and brought in a top keiki nature educator, Mrs. Terwillinger. She had all kinds of “hooks” to make learning about plants fun and fascinating. It worked because we still use her garden rhyme to explain grass vs. sedge. (I just explained weed control of nut sedge to one of our landscapers based on the “sedges have edges” concept.)
Sedges have triangular, round or square stems, while grasses have flat stems. You can touch a sedge and feel its sharp edges.
Carex wahuensis is an epic native Hawaiian sedge that should be used more in our landscapes. It is pretty and tough, and its striking chartreuse-yellow-green color really pops. It does well in tough, dry, windy, rocky sites as well as moist, sunny gardens or in pots.
If flowers are all you look for in a garden plant, you will be disappointed. But see Carex for its subtle simplicity in a landscape or restoration of native forest area and you will be impressed. A xeric (less thirsty) plant, it is showing up much more in landscapes these days, and akamai nurseries are figuring out how to grow lots of them for plugging into gardens.
My husband, Clark, and I were teaching for the University of Hawaii outreach college on Molokai when one of the students suggested we visit the hilltop teaching garden of Richard and Bronwyn Cooke. This was a marvelous and inspiring experience in a Hawaiian dryland forest that was becoming more Hawaiian every day.
Under a canopy of Hawaiian koa (replacing old plantings of alien eucalyptus) was a beautiful yellow-green clumping plant. I had to look closely to see what this land-healing groundcover was. It was Carex growing well, reseeding and looking simple and gorgeous.
Lyon Arboretum in Manoa also has some attractive and easy-to-maintain sedge plantings.
SEDGES are tougher than grasses and some say they have little economic use. Nut sedge is an alien, weedy nightmare in a “perfect” lawn, and no matter how much you dig it out, little pieces will break off and pop up again.
But if you are a weaver, you love sedges. Cyperus laevigatus was used on Niihau for crafting one of the finest mats in old Hawaii. Made from the round stems of the native sedge known as makaloa, this fine mat was as bendable as cloth and used for pa‘u (skirts), sleeping mats, capes and cloaks. Kamehameha I had a great cloak of finest makaloa, and the alii Liloa had a fine loincloth woven from the sedge.
Uki, or Cladium, is another sedge that grows in the dryland and mesic Hawaiian forest. Lei makers and weavers love the plant’s large leaves and dryable brown flower clusters.
Mauu akiaki, or Fimbristylis cymosa, is a cute little sedge we grew very well on a beach-saving sand dune in a high-end Lanikai garden. In old Hawaii, coastal dunes protected many of our beaches, and this precious sand is now mostly used to make concrete. Auwe! If we restore and protect our coasts with dunes and native plants, we might slow down loss of sand, beaches and coastal roads.
Ahu awa, or ehu awa, is a Hawaiian sedge grown in water gardens that was used to strain awa. Its scientific name is Cyperus javanicus. Other sedges include the ancient cultivated water plant Cyperus papyrus, used by ancient Egyptian papermakers. It is also edible and used for fiber, rope and cordage. Eleocharis dulcis, Chinese water chestnut, is also used for weaving mats, baskets and hats.
Fun to know all of this, right? Mahalo to our edgy sedgeys.
Heidi Bornhorst is a sustainable landscape consultant specializing in native, xeric and edible gardens. Reach her at heidibornhorst@gmail.com.
