Plant of the Month: Hey, Xanthorrhoea, it’s always good to see ya!
I’ve been around Grass Trees for quite some time, successfully relocating some, collecting seed and propagating, watching them burn more than once and watching them grow and become established. I’m by no means an expert on them but I’ve heard a lot of things claimed about them over the years and have observed them long enough to see what’s true and what isn’t, so let’s start off by clearing up some of the myths about Grass Trees.
- They need fire to flower. No. While they do flower after being burnt, they will also flower without being burnt, not all in a population at once, but a few.
- They’re difficult to propagate. Not at all. they are easy to germinate with no special requirements and have high viability.
- They grow at a centimetre per year. Not exactly. Some don’t grow trunks at all and according to PlantNET they can grow between 0.8 and 6cm a year, depending on species and conditions. The one in my front yard (which I collected the seed of about 25 years ago) has been growing at the rate of about 3-5cm/yr since it was planted into the ground.
- You need to burn them when transplanting. No, just no! It’s a great way of killing them as it stimulates flowering which uses a lot of the plant’s stored energy reserves and your plant will probably die. (I heard the plan, I called it out, they were burnt anyway and died). I have transplanted a few (with permission, of course). You need to get as much of the root ball as possible and trim the leaves back by about a third and really water them in.
The roots need a lot of room to grow so that a trunk can develop. Therefore, if you see one with a trunk in a pot then it’s probably been collected from the wild. If you are going to buy one like that, look for the licence tag.
In this region they can vary from the fairly small and trunkless Xanthorrhoea macronema (there’s a couple at Mum’s that I think I’ve finally convinced my siblings not to mow) to the magnificent, multi-headed, 6 metre tall, Xanthorrhoea glauca found at Timor, Coolah Tops and Barrington Tops.
Xanthorrhoea translates from Greek meaning “yellow flow” referring to the resin it produces seen here after absorbing about 40mm of rain.
Sorry, but apart from “Grass Tree” they tend not to have common names.
Simplified key to the Grass Trees of the Hunter Region
Most keys rely on having the flower head but this isn’t always possible so this key is based on trunk, leaf colour and size and location and won’t necessarily work outside the Hunter Region.
Mature plants trunkless, leaves green, flower head “bottle brush” like.
Flower stem (scape) at least 10 times as long as the flower spike.
Xanthorrhoea macronema – trunk absent, leaves green. Scape (flower stem) 1-1.6m long, flower spike less than a tenth the length of the scape, 5-13cm long, 1.4-2cm diameter
Xanthorrhoea macronema, this one’s been there at least 50 years and flowers every couple of years (it’s been mown a couple of times too)
Flower stem (scape) 2-5 times as long as flower spike.
Xanthorrhoea minor – 1 collection from near Clarencetown so needs targeted survey to confirm, trunk absent, branched below ground, leaves green 1.9-3.5mm wide, scape 0.3-0.6m long, flower spike 5-12cm long, 0.7-2cm diameter.
Xanthorrhoea minor flower/seed head. Image source: PlantNET – FloraOnline
Trunkless, leaves glaucous (blue-green)
Xanthorrhoea fulva – trunk absent – branched below ground, leaves almost triangular in cross section, 1.9-3.5mm wide, 1-1.5mm thick, scape 0.2-1.6m long, 1-3cm diameter, 2-3 times as long as flower spike, spike to 10-60cm long, 1-3cm diameter, coastal locations, leaves glaucous (blue-green) periodically waterlogged sites in coastal areas North of Wyong.
Xanthorrhoea fulva. Image source: PlantNET – FloraOnline
Trunkless, leaves green, flower spike not bottle brush like
Xanthorrhoea media trunkless or with trunk to 0.3m, leaves mid- dark green 2-2.8mm wide, rhombic in cross section, scape 1-1.8m long, flower spike 35-90cm, long by 2-2.7cm diameter. On sandstone, generally south of the Hunter River with outlier collections at Sandy Hollow and Mount Cabre Bald.
Xanthorrhoea media. Image source: PlantNET – FloraOnline
To 10mm wide
Xanthorrhoea latifolia – trunk absent or to 3.6m, leaves bright green 2.4-10mm wide, 0.7 -1.7mm thick, rhombic to flattened, scape 1-2.1m long, flower spike half as long to almost as long as the scape. North from Wyong, generally within 20km of the coast.
Xanthorrhoea latifolia. Image source: PlantNET – FloraOnline
Xanthorrhoea latifolia. Photo courtesy: Paul Melehan.
Mature plants with trunks
Leaves glaucous
Xanthorrhoea glauca trunk – 1-5m high – leaves glaucous 1.3-5mm wide, 0.9-2.6mm thick, scape to 0.5-1m long, 18-46mm diameter, flower spike1-2m long, 3.5 – 7.7cm diameter generally 1.5-4 times as long as scape, mature plants often multi headed. Widespread inland usually on basalt or limestone soils.
Multi headed X. glauca showing a long unburnt “stocking” and a recent flower spike.
Xanthorrhoea glauca flowers. Nectar drop can be seen in the middle of a flower, this plant is about 25 years old and unburnt.
Leaves green
Leaves generally less than 2.5mm wide
Xanthorrhoea johnsonii – trunk to 5m high, leaves green, 1-2.5mm wide 0.8-1.8mm thick, scape 0.75-1.9m long, 7-20mm diameter, flower spike 20-120cm long, rarely to 225cm, 2-4cm diameter, in well drained sclerophyll forest and heath north and west from Singleton.
Xanthorrhoea johnsonii. Image source: PlantNET – FloraOnline
Xanthorrhoea johnsonii
Leaves generally greater than 2.5mm wide
Xanthorrhoea malocophylla – trunk 2-6m, up to 10 crowns, leaves green to bright green 2.5-3.5mm (to 6.7) by 1.3-2.4mm thick (usually spongy and soft), scape 1.3-1.8mm long by 2-3cm diameter, flower spike 0.6-1.6 times as long as the scape, 110-180cm long, 3-5cm diameter. Moist or wet sclerophyll forests and rainforest margins on rocky hill sides, coastal areas north from Wyong, inland to Dungog and Gloucester.
Xanthorrhoea malocophylla. Image source PlantNET – FloraOnline
Xanthorrhoea latifolia – see above
Illustrations source:
PlantNET (The NSW Plant Information Network System). Royal Botanic Gardens and Domain Trust, Sydney. https://plantnet.rbgsyd.nsw.gov.au [website accessed 26.05.2026]
Photo credits: Paul Melehan