Home & Garden Columns

Green Neighbors: Celebrating the Classic Cordyline

By Ron Sullivan
Tuesday January 22, 2008

I don’t know how old you have to be to think of Sunset magazine and early 1960s swimming-poolside dioramas whenever you see a Cordyline australis in its other vocation, as a plain old yard or streetside tree. It’s a classic, though, to complete the post-TK look that starts with a turquoise pool, maybe kidney-shaped, and a Weber kettle. Some of us get whiffs of vinyl, chlorine, and firestarter fluid from our subconscious every time.  

It wasn’t just aesthetic, that fad for “cabbage tree.” Certainly it fit that angular, minimalist, post-Thomas Church look. But its practical virtues include toughness—it won’t flinch from regular sloshing with chemical-laden pool water—and big sturdy leaves that don’t disintegrate and clog the pool filter and don’t get shed often anyway.  

That fibrous toughness has brought cordyline halfway ‘round the world: a few years back, I heard a member of a group of visiting Maori artists laughing about how seeing it and New Zealand flax all over the landscaping made her feel right at home.  

Cordyline has been around the block taxonomically speaking, too. In older books it’s a member of the Amaryllis family. The most recent Sunset Garden Book has it in the Agavaceae, as are the dracaenas. In fact it was at one point assigned to the genus Dracaena, along with the dragon tree and all those indoor plants. Now it’s not even in the same family. In the latest classification dracaenas share the family Ruscaceae with lilies-of-the-valley, Solomon’s-seals, and Sansevieria, the house plant variously known as snake plant, bowstring hemp, and mother-in-law’s-tongue. This week, cordylines—including the Hawai’ian ti plant, C. fruticosa—appear to be in the closely related family Laxmanniaceae.  

Plant taxonomy can be brutal—more so since the geneticists got into the act. They’ve really done a job on the monocots, the plant clade that includes lilies, palms, and grasses. The lily family has been shrunk radically, with all kinds of plants that used to be lilies spun off into their own families. True lilies (like tiger lilies and the showy Oriental types), tulips, fritillaries, and fawn lilies are still lilies, and that’s about it. 

One likely reason that agaves, yuccas, and cordylines were lumped together in the first place, apart from their pointy leaves, is that all three groups include woody species. In general, with the great exception of the palms, monocots don’t get woody. Monocot timber, according to Colin Tudge’s The Tree, is highly variable in structure, and not much like either conifer timber (pines and redwoods) or dicot timber (oaks, mahoganies, and other such broadleaf trees).  

Conifers and dicot trees share the phenomenon called secondary thickening, in which a complete cambium sheath, the live underskin of xylem and phloem just beneath the bark, allows a tree to get thicker and thicker, for years or centuries as it relinquishes its circulatory function and lignifies into supportive heartwood. Dragon trees and cabbage trees have reinvented this strategy, but somehow manage it without the cambium sheath. 

C. australis is tree enough to be included in the Collins Handguide to the Native Trees of New Zealand, where it grows in swampy areas and lower montane forests up to 2,000 feet. Just as cacti on the Galapagos Islands evolved tall tree-like forms under pressure from grazing giant tortoises, the cabbage tree may have been spurred to treehood by the moas, the giant flightless birds that took over the role of browsing mammals on those mammal-less (except for the bats, who don’t graze much) islands. 

When the Maori discovered New Zealand, they recognized the cabbage tree—which they called ti rakau, ti kouka, or whanake—as a potential food source. The pith of young stems was eaten raw, boiled, or baked in earth ovens; roots required longer cooking They must have been patient as well as adventurous, culinarily speaking. Ti kouka was a major dietary starch, along with fern roots. After intensive processing, cordyline roots yielded a juice that they used as a sweetener; other extracts made traditional medicines.  

The Maori also fashioned ropes from trunk and root material and used fiber from the leaves, along with those of another of our landscape favorites, New Zealand flax, Phormium tenax, to make clothing and sandals. There’s good evidence that they developed cultivars for different purposes.  

Early European missionaries were said to have “brewed a tolerable beer” from cordyline, although just what an early missionary would tolerate is an open question.  

As “mid-century modern” architecture—those Eichlers and the Thomas Church gardens that, if their owners are incredibly fortunate, accompany them—get dragged back into fashion, maybe we’ll be seeing even more cordylines in the landscape. Until then, just hail every one you see as an historical marker. Let’s refrain from any discussion of giving them landmark status just yet, though.  



Photograph by Ron Sullivan. 

A streetside tree dreams poolside dreams: Cordyline australis.