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Leionema dentatum

Toothed Phebalium

Family: Rutaceae

A shrub or small tree, potentially reaching 6 metres high, with round stems.

It is endemic to NSW, with a mainly coastal distribution in NSW; with a disjunct occurrence between Grafton-Glen Innes and Tenterfield (Gibraltar Range National Park), then with records surrounding the Sydney area, extending to Wollongong and the Southern Highlands; with another disjunction to the Moruya area.

It grows in dry sclerophyll woodland and forest, mainly on sandstone.

Leionema spp. have characteristics matching those of other similar Rutaceae genera (Philotheca, Phebalium, Crowea); i.e. simple, alternate leaves, usually with oil glands.

In this species, leaves are linear to oblong to narrow-elliptic to oblanceolate (wider part at apex), to 8 cm long and 0.8 cm wide with toothed margins, with white undersides due to stellate (star-shaped) hairs. The margin-teeth can be obscured due to the leaf edges rolling down and inwards; leaves with an aroma.

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 inflorescences consist of up to 10-flowered clusters in leaf axils, yellow or white with pale yellow anthers, which are then clustered into larger groups, often in dense masses, occurring in 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 3.5 mm long.

In the garden

This species is not widely known to be cultivated. It may be difficult to grow or may not have been trialled sufficiently. Check with local native nurseries for availability.

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).  

Propagation

In common with most members of the Rutaceae, propagation from seed is difficult but cuttings usually strike readily.

Other information

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.

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.

dentatumLatin meaning “toothed”, referring to the margins of leaves.

This species is not considered to be at risk of extinction in the wild.

NSW Flora Online (PlantNET) – Leionema dentatum profile page

https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Leionema~dentatum

Wikipedia – Leionema and Leionema dentatum profile page

https://en.wikipedia.org/wiki/Leionema

https://en.wikipedia.org/wiki/Leionema_dentatum

Friends of Lane Cove National Park – Leionema dentatum profile page

http://www.friendsoflanecovenationalpark.org.au/

Australian Native Plants Society Australia –

Poor Relations – Phebalium / Leionema / Nematolepis

http://anpsa.org.au/APOL20/dec00-4.html

By Jeff Howes, edited Dan Clarke