Xanthorrhoea

Like a parent, a gardener should never have favourites. But you do, don’t you? Can’t help it. The grasstree Xanthorrhoea is one of three favourites in my garden that I can’t pick between, each of them achieving ‘Best in Garden’ status for completely different reasons.

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So what does the grasstree do for me? Well firstly, with apologies to gums and wattles, I don’t think there is a more visually distinctive Australian plant. But to get a spot in my little garden, a plant has to have more going for it than mere localism. It has to please the eye as well.  What I find so endearing about this plant is its unique form, the mop of arching grey-green leaves, the collar of scruffy dead brown leaves, the squat, blackened and crooked trunk, and the spear of the flower spike, thrusting heavenwards.  You see a grasstree in the landscape, and you know you are not in Kansas anymore. You can only be in Oz.
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Grasstree 7Xanthorrhoeas are superbly adapted to the hungry soils and firestorms of this dry continent. They only flower and set seed after a good fire enriches impoverished soils with a bit of extra nutrient to assist new seedlings through that first difficult year.

Traditionally, they  provided a handy kit of resources to Aboriginal Australians. Nectar was collected from the the long flower spikes. The heart of the stem is edible as is the base of the leaf which has a light nutty flavour. The light wood of the scapes (flower stalks) were used as the tinder base of fire drills (disparagingly known as rubbing two sticks together to make fire). Because of the light wood, the long scape was also used to make spear shafts. Then they’d use the hard resin exuded from the caudex to fasten spearhead to the shaft. The hard leaves are really sharp and were used for cutting meat. I can vouch for this because they sliced my fingers deeply more than once as a kid

Xanthorrhea in Singapore botanical gardens

Magnificent double headed Xanthorrhea in Singapore botanical gardens

They won’t flower unless they smell smoke in the air which initiates the flowering process. Indeed, that’s how I get mine to flower so frequently. I also like it that they are such slow growers. My garden is so small that most plants need to be regularly trimmed to size or cut down completely when they get too big in order to maintain the scale and proportions of the garden, but not the Xanthorrhea. The trunk on mine has managed to grow about a metre in 20 years. (A bit vague because it’s a bit hard to say exactly where trunk stops and leaves start.)

My plant was minuscule to start with, a trunk of less than 20 cm with a small tuft of punk-like spiky leaves poking out the top. Didn’t look like it would ever amount to much. But I couldn’t afford the prices being charged for the big ones with trunks the size of Greek columns getting planted out at hip cafes and funky apartment developments in the mid-90s. Well most of those giant plants died, or were replaced by cacti when the fad passed. They failed because they were either planted into heavy clay soils, or transplanted into a pot with a too-small root ball.

That fashion and its aftermath gave Xanthorrheas a reputation for being difficult, which is unfair. You see, if you remove too much of the rootball that gives them their drought tolerance when transplanting, they’re cactus, and your hip cafe needs a style makeover. Those massive Greek columns need massive rootballs to support them. Also, the root system is particularly vulnerable to cinnamon fungus, Phytophthora cinnamomi, which kills off the fine root hairs.  They are the canary in the coal mine, the first species to die off in bushland contaminated with this nasty soil borne disease. But if you keep the cinnamon fungus away, start with a small plant, and your soil has good drainage, they are dead easy to grow.
I purchased mine on impulse, to see if I could make a go of these unique plants, (always a risky design option). ‘Once upon a time they grew here naturally,’ I figured. ‘They can’t be too hard to grow.’ Famous last words that a lot of plants hear on becoming my impulse purchases. But this time they weren’t a death sentence. It loved my sandy soil, didn’t mind the salty sea breezes, and survived the Millennial Drought without a drop of extra water, all the time growing at about 5cm a year. All I had to do was make sure when I augmented the rest of my garden soil with truckloads of organic matter (for the more sensitive little flowers), I didn’t add a skerrick to the ground where the grasstree now stands. Oh yes, and I also set fire to the grass skirt every 15 years or so to make sure the trunk remains black. That’s quite a sight. Myrna freaked right out thinking the fire brigade would turn up any second to drown it.
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While including the grasstree in the garden was based on sound ecological design principles, placement of the grasstree at the end of the small mound behind the pond was definitely more arse than class. At the time I laid out the garden, our house was being renovated, so we didn’t really know how we would end up using the space. It turns out we spend a lot of time on the back deck or in the back room, and from there the grass tree is smack bang in the middle of the garden. As the focal point in the asymmetric design, the grasstree makes a powerful visual statement, particularly as it ages. With thick black trunk and arching foliage that plays with sunlight like a fountain when sea-breezes blow, it makes for an eye-catching centrepiece.

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I wanted a strong vertical element to contrast with the rounded and cascading forms that predominate visually. I planted a dwarf thuja for this effect, but it bolted like a frightened horse in this Sydney climate and had to go after 10 years. All out of proportion! But now the Xanthorrea gives us vertical in spades. In fact looking at the powerful upthrust of its flowering, you’d swear I’d been feeding it Viagra. When the flowering spikes emerge they can grow an extraordinary 20cm a day. It starts with just a tiny knob poking out among the spaghetti bowl of leaf bases. Next it’s folded back on itself like a little handle at the top of the plant. Then it just races for the sky… an exciting time just to come home and see how much it grew today.

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And right now it’s especially exciting. A couple of years ago I noticed that the plant appeared to be developing two crowns. But the arrangement of leaves is so crowded and jumbled up at their bases that it was impossible to tell for sure. A couple of weeks ago I noticed a flower spike emerging through this spaghetti bowl. And then last week I noticed a second spike emerging. Two spikes! Yes. Now I can be sure that the grasstree has definitely branched.

 

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