Eremophila glabra

Tar Bush
Eremophila glabra in Mount Annan Botanic Garden
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Eudicots
(unranked):	Asterids
Order:	Lamiales
Family:	Scrophulariaceae
Genus:	Eremophila
Species:	E. glabra
Binomial name
Eremophila glabra (R.Br.) Ostenf.

Eremophila glabra, commonly known as tar bush, is a plant in the figwort family, Scrophulariaceae and is endemic to Australia. It is sometimes a low, ground-hugging and sometimes an erect shrub. The leaves are variable in size and shape and there is a range of flower colours. In spite of its scientific name, not all forms of the plant are glabrous but most have many small, raised glands on the stems, flowers and leaves.

Description

Eremophila glabra grows to 0.1–3 metres (0.3–10 ft) in height, sometimes a prostrate shrub and sometimes erect. The leaves are arranged alternately, sometimes crowded, other times sparse, usually lance-shaped but they may also be linear to egg-shaped. They are 7.5–61 millimetres (0.3–2 in) long and 0.8–18 millimetres (0.03–0.7 in) wide, the end pointed and the base tapering gradually towards the stem. The leaves and stems are covered with small, raised glands.^[1][2]

The flowers are red, orange, yellow or yellowish green, lack spots and are arranged singly or in pairs in the leaf axils on a stalk which is 3–10 millimetres (0.1–0.4 in) long. There are 5 sepals which are narrow egg-shaped to triangular and of slightly differing lengths. The petals, which give the flowers their colour are 20–30 millimetres (0.8–1 in) long and joined in a tube with 5 lobes at the end. The upper lobes are pointed and usually close together while the lower lip is blunt and bends backwards. There are four stamens which extend beyond the end of the petals. Flowering occurs between early autumn and summer (March to December in Australia) and is followed by fruits which are oval to almost spherical, about 4–9 millimetres (0.2–0.4 in) in diameter, glabrous, dry or fleshy and dark brown.^[1][2][3]

Eremophila glabra 'Murchison Magic' in Maranoa Gardens, Balwyn, Victoria

Eremophila glabra typical habit

Taxonomy

The species was first named in 1921 by Carl Hansen Ostenfeld in the journal Biologiske meddelelser, Kongelige Danske Videnskabernes Selskab.^[4] It was first formally described in 1810 as Stenochilus glaber by Robert Brown in Prodromus Florae Novae Hollandiae et Insulae Van Diemen.^[5][6]

Subspecies

The following subspecies have been described by R.J.Chinnock although there may be others not yet described:^[1]

• Eremophila glabra subsp. albicans (Bartl.) Chinnock^[7]
• Eremophila glabra subsp. biflora Chinnock (in manuscript)^[8]
• Eremophila glabra subsp. carnosa Chinnock^[9]
• Eremophila glabra subsp. chlorella (Gand.) Chinnock^[10]
• Eremophila glabra subsp. elegans Chinnock^[11]
• Eremophila glabra (R.Br.) Ostenf. subsp. glabra^[12]
• Eremophila glabra subsp. murrayana Chinnock^[13]
• Eremophila glabra subsp. psammophora Chinnock^[14]
• Eremophila glabra subsp. tomentosa Chinnock^[15]
• Eremophila glabra subsp. verrucosa Chinnock^[16]

The specific epithet glabra is a Latin word meaning "smooth" or "hairless"^[17] possibly referring to the hairless ovary of this species.^[1]

Distribution and habitat

Eremophila glabra occurs in all the mainland states of Australia. Eremophila glabra subsp. glabra is the most widespread and it occurs in a wide range of soils and vegetation associations, although only in the drier areas of the continent.^[1]

Conservation

The species is not threatened however Eremophila glabra subsp. chlorella is classified as "threatened" by the Western Australian Government Department of Parks and Wildlife^[3] meaning that it is rare and in need of protection.^[18]

Use in horticulture

Eremophila glabra is popular in native gardens and a number of cultivars have been developed. A yellow flowered, prostrate form is available as is the variety "Murchison Magic", a silvery-leaved form with red flowers. Propagation from seed is difficult but cuttings strike readily and preserve the features of the parent plant.^[19] It is one of the hardiest eremophilas in cultivation, performing best in a sunnpy position with well drained soil.^[20]

References