Philotheca obovalis is a shrub to 1 metre tall, with slightly hairy stems.
It is mainly found in the Blue Mountains area of NSW, between Springwood-Katoomba, northwards to east and north-east of Cullen Bullen. There are some disjunct records (possibly erroneous) further south with a verified patch much further south north-east of Nimmitabel at Kydra (Kydra Mountain) on the southern tablelands.
It is found in heathland and shrubland on sandstone.
Philotheca spp. have simple and alternate leaves (a trait it shares with its relative, Citrus), often with conspicuous oil glands and odorous.
In this species the leaves are broadly ovate to cordate (heart-shaped) with the narrower end towards the base, to 10 mm long, and to 10 mm wide and slightly warty on the lower surface.
Philotheca spp. produce flowers in leaf axils or at the terminals, often reduced to single flowers with leaves in-between or in cymose or racemose groups. Flowers have 5 sepals (rarely 4) and 5 petals (rarely 4).
In this species, flowers are borne singly in leaf axils on a pedicel to 3 mm long with six small bracteoles at the base, with white petals, sometimes tinged with pink, with flowers up to 15 mm across and about 6 mm long, occurring in Spring.
The fruit of Philotheca is a schizocarp-capsule – which splits into equal segments on maturity which each segment called a coccus (plural cocci). In this species, the capsule is about 4.5 mm long.
Not much is currently known about the cultivation of this species. It is not often cultivated and is reported to be unreliable. This may be due to its natural habitat in higher areas.
It requires a well-drained moist soil, preferably in semi shade and should be given reliable moisture.
Philothecas can be challenging to grow but often with more success than the related Boronias. They are very attractive in flower and well worth the effort.
In a garden situation, they grow best in a well-drained soils in full sun. They can succumb quickly to poor drainage. Place in a well-drained sandy soil, in semi-shade to full sun, preferably on a slope. Lightly prune after flowering to maintain compact shape. Flowers attract bees and butterflies.
Very useful in rockeries and sloping gardens.
In common with most members of the Rutaceae, propagation from seed is difficult. Cuttings usually strike readily from current season’s growth but some species can be slow to form roots.
Philotheca is a genus of about 50 species, all are endemic to Australia with species in every state except the Northern Territory. NSW currently has 16 species. Many plants formerly in Eriostemon are now in this genus.
Most Philotheca plants would die in a fire and regenerate from the seedbank.
Philotheca – was first described by Edward Rudge in 1812. As there are some reported variations on the meaning – the Latin of Rudge in his publication was transcribed for these profiles as follows:
all as in Eriostemone, but the habit is very different from that of the ericoid branches; The terminal flowers and the filaments below, enlarged into the naked box, whence the name.
It has been reported that Psilos (ψιλός) refers to “naked” or “bare” in Ancient Greek. Philos (φίλος) in Greek tends to mean “friend”. Philia (φιλία) in Ancient Greek means “highest form of love”
The suffix -theca refers to “box” or “case” in Ancient Greek. Hence, it is thought the name means “naked-box” or “loving-box” referring to the condition of the 10 (or 8) stamens that are fused at the base and forming a box-like structure. (Note: this is not the case in all species with some having free stamens).
obovalis – from Latin ob – meaning “reversely” and ovalis meaning “oval”, referring to the obovate leaf shape (widest at terminal).
This species is not considered to be at risk of extinction in the wild. It is regarded as rare in the wild and classified as 3RCa under the ROTAP (Rare or Threatened Australian Plants (Briggs and Leigh, 1988)) publication).
NSW Flora Online (PlantNET) – Philotheca obovalis profile page.
Wikipedia – Philotheca obovalis profile page
Australian Native Plants Society Australia – Philotheca obovalis profile page