Southern Grasstree

by Brendan
Publish date
1 April 2012
Comments (9)

Exhibition horticulturalist Brendan Fleming is turning April's Bug of the Month post into Plant of the Month. He is one of the Live Exhibits staff that tend the plants in the Forest Gallery and Milarri Garden.

From an early age I have enjoyed bushwalking within the Grampian Ranges in western Victoria. One particular plant species found there that fascinates me is Xanthorrhoea australis, the Southern Grasstree. X. australis is the most widespread of the genus of 30 odd species and subspecies. It is found down the eastern coast of Australia.

Southern Grasstrees A spectacular display of Southern Grasstrees following a bushfire in the Grampians.
Image: Brendan Fleming
Source: Brendan Fleming

Its appearance is unlike any other indigenous plant. Older grasstrees have a blackened, sometimes gnarled elevated trunk, with bluish-green whorled leaves that seem to explode from the crown and drape down to skirt the stem.

The Southern Grasstree is very slow-growing. It grows approximately one to three centimetres per year, reaching a height of three metres in about 100 years. It has a shallow root system and is found in even the poorest of soils. Whilst not generally occurring in areas with less than 250mm rainfall, it does best in areas exceeding 500mm per year. Southern Grasstrees are found in the understorey of woodlands, heaths, swamps, and rocky hillsides.

Grasstree species are mostly distinguished by the shape of their leaves in cross-section. X.australis has a diamond shape, and with the leaves being softer than other species.

apex of a Southern Grasstree Close up of the apex of a Southern Grasstree in Milarri, showing a single diamond-shaped leaf in cross section.
Image: Brendan Fleming
Source: Museum Victoria

From germination it takes about seven years to reach maturity, and although sporadic flowering and fruiting can occur thereafter, X.australis generally flower following fire. It is not well understood why fire stimulates reproduction, but cutting off the leaves can also initiate flowering. Application of ethylene, which is present in smoke, has a similar effect, indicating that flowering is stimulated from a hormonal response to leaf removal.

I found an extraordinary scene following bushfires several years ago in the Grampians National Park. Thousands of flower spikes up to 3m high as far as the eye can see, even curly ones, evoking some Leunig illustration!

Grasstree flower spikes Although most flower spikes are perfectly vertical, I occasionally see odd shapes at the Grampians.
Image: Brendan Fleming
Source: Brendan Fleming

The flowers are highly scented and produce much nectar, prized by birds, mammals and insects which pollinate the flowers. Each stalk can produce up to 10,000 seeds.

Southern Grasstree flower spike Close-up of the Southern Grasstree flower spike showing individual flowers.
Image: Brendan Fleming
Source: Brendan Fleming

Southern Grasstrees are quite susceptible to Phytopthora cinnamomi (root rot), often being the first plants to show symptoms. Hence they are a good indicator of the presence of the disease.

Drenching Southern Grasstree roots with Phosphonate Drenching with Phosphonate is a good way to boost the Southern Grasstree's defences against the Cinnamon Fungus Phytopthora.
Image: Chloe Miller
Source: Museum Victoria

Xanthorrhoea australis is not difficult to propagate. Seed germinate readily in just a few weeks, with no pre-sowing treatment required. Just be patient though - growth is very slow. A grasstree I germinated from seed was well-established but still trunkless after 10 years, and made a handsome addition to my garden.

Grasstrees feature heavily in Indigenous culture. Uses include weapons and fire sticks from flower stalks, sweet drinks from flower nectar, and edible leaf bases.

I don't have to go to the Grampians to enjoy grasstrees. The Milarri Garden at Melbourne Museum displays these remarkable plants right in the heart of Melbourne. Exit the Forest gallery to the North terrace and meet Milarri from its western end. It really is a dramatic entrance to the Museum's Indigenous garden.

Grasstrees at the entrance to Milarri Walk Grasstrees at the entrance to Milarri Walk from the North Terrace during autumn.
Image: Brendan Fleming
Source: Museum Victoria


Flora of Tasmania

Wrigley, J. & Fagg, M., 1983, Australian Native Plants, William Collins, Sydney, 512pp.

Comments (9)

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Gen 2 April, 2012 08:49
Nice one Brendan! Very interesting...
Rod 2 April, 2012 14:35
Great post.
Tamzin 9 November, 2012 17:42
Hi Brendan, this is a great article. I was wondering if you'd know where I could get some information about caring for an unwell grass tree (not transplanted, but growing in its original site).
Discovery Centre 17 November, 2012 11:40

Hi Tamzin, Grass Trees like well-drained soils and prefer full sun. They transplant reasonably well, preferably during the cooler months, so if the soil is too wet or too heavy, or if the site is too shaded, you may need to consider moving it. In this case it will need to be dosed regularly with a root stimulant such as seaweed extract after transplanting.

Grass Trees are susceptible to Phytophthora, which can kill them quite quickly. In this case a fungicidal drench around the roots will help. One way to recognise Phytophthora is that the leaves are easily pulled out from the crown.

Keep in mind that even when a plant appears to be in poor condition, it can sometimes recover of its own accord and start producing green shoots unexpectedly after relatively long periods of looking poorly.

If you need more advice, please send a couple of photos to give us a better idea of what the problem may be, you can email us at

Rod Barwick 15 November, 2014 12:08
Hi I have grown some grass trees from seeds maybe 2-3 years ago. I have planted 4 out into the garden but one just died. The other three just seem to be sitting . A few new leaves in the middle that I can't pull out but some dying off around the outside. I have one more in a large pot that seems to be best of all. I realise they are Slow growing but wonder if I am doing anything wrong .? They don't have many leaves or they branches? Would appreciate your suggestions. Thanks rod
Discovery Centre 20 November, 2014 14:51

Hi Rod,

Some native plants tolerate and flourish from planting as a ‘tube’ specimen, but it is likely that a grasstree seedling might be better to grow on for some time to develop a robust root system before planting out. Very small plants can often get covered by leaf litter, picked at by birds, could possibly dry out if in full sun, etc.

Always use a premium potting mix for your potted plants, it does make a difference. Also wait until it gets a reasonable amount of root development, then pot it up to a larger size, for example a 2” to 6” pot, then on to an 8” pot... Some gardeners opt for planting out from a 6” pot but the larger the plant/pot size the more surety you would have of survival and establishment in your garden.

Hope this helps, and good luck!

Libby 17 October, 2015 07:17
I wonder if you could help me, I live in the Mallee and would love to grow these beautiful southern species from seeds in pots, can you recommend where I can get seeds from or do you sell southern grass trees from seeds? Thanks for your help.
Jen Austin 16 November, 2016 14:20
Hi Brendan, love the info and the photos are excellent. Two questions (unrelated) for you. 1. To collect seed from Xanthorrhoea minor, can you shake the spike when it's still white and pollen like (and keep seed in paper bag til hard) or do you have to wait until flower spike is dried and dark? 2. I have 2 x Hymenosporum flavidum in my garden. I wish to move them out of the proposed vegetable patch area. They are about 6 years old and about 2.5-3 m tall each. Can I transplant these successfully? I can not find any info about transplanting them anywhere. Cheers Jen
Discovery Centre 19 November, 2016 09:42

Hi Jen, Brendan has provided the following information, collecting seed from Xanthorrhoea minor is an easy task. Once the ‘furry’ small flowers wither, the flower spike will brown and harden, and form multiple seed cases. This may take months, then the capsules will open and the seed can be extracted. Seed may fall to the ground, but best if the dry flower spike is removed. It just means that ongoing monitoring of the drying spike needs to be done. Others may extract seed another way but this is what I did in Milarri Garden with the grasstrees there and it was fine, seed was easy to extract and they germinated readily, in just four weeks.

Transplanting evergreen shrubs and trees can be tricky. Especially now that the weather is warming. 6 years is quite a while to be growing in the ground, meaning that it has probably got a reasonable root system, and root systems don’t like disturbance. 2.5-3 metres in height is getting up there. Generally a plant should be reduced in size when transplanting…..unfortunately hymenosporums are often leggy and don’t have leaves all the way down the stems, so it is not possible to cut back to leaves. What I mean is, it’s not advisable to cut back to a bare stem/trunk. Some plants will re-shoot, but I cannot say for hymenosporum, because I have never pruned one hard, or pruned to bare wood. Also, prior to shifting a plant, it can be a good idea to dig a trench around the trunk some weeks prior to removal, as this can prepare the plant for moving, giving it less of a shock. The aim is to get as big a root ball as is possible, giving the tree the best chance. Soil is heavy so this is a tough task. I’d cut the tree back by half, main trunk & branches, so as to reduce leaf. Give the hole at the new site plenty of water before transplanting. Important to water in with a seaweed product, as seaweed is a top stimulant for root growth. Fortnightly applications/drenching with seaweed solution is advisable following transplantation. You might be lucky and it might establish well. Some horticulturists would probably advise against transplanting now, as the cooler months would give a better chance of success, but if it was me and I wanted to shift them, I would give it a go, but I wouldn’t leave it another day, because of impending warmer temperatures. If it doesn’t establish, don’t stress. Plants are cheap for what you get in return. Good luck.

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