A shrub to 2 metres or more high, with young stems appearing white due to dense stellate (star-shaped) hairs.
It has a very restricted distribution, growing between Katoomba and Blackheath
It is found on sandstone outcrop (cliff tops and benches) in heathland and mallee-shrubland.
It is listed as being threatened with extinction in the wild, and is known to occur at 10 sites.
Leionema spp. have characteristics matching those of other similar Rutaceae genera, (e.g. Philotheca, Phebalium, Crowea); i.e. simple, alternate leaves, usually with oil glands.
In this species, leaves are tubular (terete), crowded along the stems, to 20 mm long, by about 1 mm wide, usually curving upwards and aromatic when crushed.
Leionema spp. have 5-merous flowers; i.e. 5 sepals, 5 petals and usually 10 stamens surrounding 5 carpels, with an overall attractive star-shaped appearance. Flowers can be produced in leaf axils or branch terminals, in cymose clusters or solitary.
In this species, flowers are produced solitarily in upper leaf axils, to about 10 mm across, yellow in colour, appearing in winter to spring.
The fruit of Leionema is a schizocarp-capsule – which splits into equal segments on maturity which each segment called a coccus (plural cocci).
In this species, the fruit has been observed but not really described.
This species is not widely known to be cultivated. This is likely due to its listed threatened and protected status. It is very rare. It grows on sandstone outcrop in heathland and may require similar conditions to grow well in a garden. It may be more widely cultivated in the future.
In cultivation, Leionema spp. prefer well drained (sandy to sandy loams), acidic soils in dappled shade or morning-light positions. They are highly-drought tolerant once established but benefit from some supplementary watering. It is advised to add some slow-release fertiliser when first planted and they will benefit from periodic organic fertilising (eg: blood and bone or seaweed solution).
It has been reported that species in this genus should be cultivated more widely and simply need more attention and effort (see Australian Native Plants Society Australia weblink in the references).
In common with most members of the Rutaceae, propagation from seed is difficult but cuttings usually strike readily.
Leionema are a genus of 28 known species, 27 of which are endemic to Australia, with 1 species endemic to New Zealand. These species have been previously classified in the genus Eriostemon and Phebalium. Leionema differs by not having anthers with an apical point or gland, as well as free sepals on the flowers and small bracteoles on the middle to upper part of flower stalks (pedicels).
Most Leionema spp. would likely die in a fire and regenerate from seed. Some basal regrowth or stem-reshooting may be possible. This species is known to regenerate in substantial numbers from seed after fire.
Leionema – from Greek leios (λείος), meaning “smooth”, and nema (nήμα), a thread, referring to a ‘hilar strand’; a small piece of tissue joining the hilum (a scar on the side of the seed) to the ovule.
lachnaeoides – Latin – resembling species of the genus Lachnaea. a genus of South African heathland plants, related to Pimelea.
This species is listed as being threatened with extinction in the wild at the State and Commonwealth level with the category of Endangered.
NSW Flora Online (PlantNET) – Leionema lachnaeoides profile page
Australian Native Plants Society Australia – Poor Relations – Phebalium / Leionema / Nematolepis
NSW Office of Environment and Heritage – Leionema lachnaeoides profile page