Prostanthera ovalifolia

Oval-leaf mintbush
Prostanthera ovalifolia at Eastwood, New South Wales
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Clade:	Asterids
Order:	Lamiales
Family:	Lamiaceae
Genus:	Prostanthera
Species:	P. ovalifolia
Binomial name
Prostanthera ovalifolia R.Br.
Occurrence data from AVH
Synonyms
Prostanthera ovalifolia R.Br. var. ovalifolia Prostanthera incisa auct. non Benth. in Stanley, T.D. & Ross, E.M. (1986)

Prostanthera ovalifolia, commonly known as the oval-leaf mintbush or purple mintbush, is a species of flowering plant in the family Lamiaceae and is endemic to south-eastern continental Australia. It is an erect shrub with egg-shaped leaves and groups of mauve to deep blue-purple flowers arranged in groups at the ends of branchlets.

Description

Prostanthera ovalifolia is an erect, spreading to dense shrub that typically grows to a height of 1–4 m (3 ft 3 in – 13 ft 1 in) with stems that are square in cross-section and are moderately hairy. The leaves are egg-shaped, a lighter shade of green on the lower surface, 5–50 mm (0.20–1.97 in) long and 3–12 mm (0.12–0.47 in) wide on a petiole 1–6 mm (0.039–0.236 in) long. The flowers are arranged in groups at the ends of the branchlets with bracteoles 1–2 mm (0.039–0.079 in) long and 0.2–0.3 mm (0.0079–0.0118 in) at the base, but that fall off as the flowers develop. The sepals are 2–3.5 mm (0.079–0.138 in) long and form a tube 1–2.5 mm (0.039–0.098 in) long with two lobes, the lower lobe 0.5–1.5 mm (0.020–0.059 in) long. The petals are mauve to deep blue-purple and fused to form a tube 6–18 mm (0.24–0.71 in) long. Flowering occurs from August to November.

Taxonomy

Prostanthera ovalifolia was first formally described in 1810 by Robert Brown in his book Prodromus Florae Novae Hollandiae et Insulae Van Diemen.

Distribution and habitat

Oval-leaf mintbush is widespread in forest growing on sandstone in south-eastern Queensland and eastern New South Wales. It is also sporadically naturalised in the eastern half of Victoria.

Use in horticulture

This mintbush is widely cultivated as a garden shrub where it typically grows to a height of about 2.5 m (8 ft 2 in). It grows best in a well-drained soil with some protection from direct summer sun. It should be pruned back by about one third to retain its bushy shape.