A shrub to 3 metres high with angled stems and with stellate (star-shaped hairs).
It has a restricted distribution in the wild, growing east of Rylestone and Kandos, towards Nullo Mountain State Forest, near Mount Gangang and Rams Head Mountain, and within Capertee Valley.
It is found growing on rocky outcrops in dry sclerophyll forest and woodland.
It is listed as being threatened with extinction in the wild.
Leionema spp. have characteristics matching those of other similar Rutaceae genera, (e.g. Philotheca, Phebalium, Crowea); i.e., simple and alternate leaves, usually with oil glands.
In this species, leaves are flat, to 35 mm long by up to 10 mm wide, elliptic to oblanceolate, toothed margins towards the apex, mid to dark green.
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, the flowers are comparatively unique in that the petals are fused into a tube (resembling those of Correa), occurring in clusters of 1 to 3, in upper leaf axils; to about 15 mm long and green-yellow in colour, occurring 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).
The capsule is approximately 4 mm long in this species.
This species is not widely known to be cultivated. This is likely due to its listed threatened status. It may be more widely cultivated in the future. It has an attractive differing feature in that the flowers are tubular which would make it a great addition to a garden. It grows on rocky areas and may require very good drainage.
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. NSW currently has 15 species.
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 thought to regenerate from seed.
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.
sympetalum – Latin, meaning “fused-petals” or “joined-petals”, referring to the flowers having the 5 petals fused together in a tube.
This species is listed as being threatened with extinction at both the State and Commonwealth level with the category of Vulnerable.
NSW Flora Online (PlantNET) – Leionema sympetalum profile page https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Leionema~sympetalum
Wikipedia – Leionema and Leionema sympetalum profile page https://en.wikipedia.org/wiki/Leionema
Australian Native Plants Society Australia – Poor Relations – Phebalium / Leionema / Nematolepis http://anpsa.org.au/APOL20/dec00-4.html
NSW Office of Environment and Heritage – Leionema sympetalum profile page https://www.environment.nsw.gov.au/threatenedspeciesapp/profile.aspx?id=10458