Oldenburgia grandis

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Botanical Name

Oldenburgia grandis

Family

Asteraceae - The daisy family.

Pronunciation

old-en-BUR-gee-uh GRAN-dees / GRAN-dis

Common Name(s)

English: Donkey Ears; Suurberg Daisycushion; Suurberg Cushion Bush; Rabbit's ears; Lamb's ears

Afrikaans: Suurbergkussingbos; Lepelboom; Bastersuikerbos; Kreupelbos

Plant Group

Tree A woody, self-supporting perennial plant usually with a single main stem and generally growing more than 6 meters tall.

Plant Size

Very Small

Tree 3m to 4m

Shrub 25cm to 50cm

Perennial/ground cover Up to 10cm

Bulb 10cm to 20cm

Succulent Up to 5cm

Position

Sun The area is in full sun for all or most of the day, all year round.

General Information

Drought Tolerance: High The plant is well adapted to arid conditions; it can survive long periods of drought and high temperatures without extra water.
Evergreen Plants that have leaves all year round.
Frost: Half-hardy The plant is able to survive low temperatures and some frost but requires protection against severe frost.
Frost: Tender A plant that will not survive any frost or low winter temperatures.
Water Wise Plant species originating from low rainfall regions that require less water to survive and thrive than other plant species.
Wind Tolerant Plants able to withstand the effect of strong winds.

Specific Information

Oldenburgia grandis is a unique, long lived, small tree or large shrub with gnarled, twisted branches and corky bark. The oblong leaves are stalk-less, stiff and leathery and are held in rosettes at the ends of branches. Mature leaves are shiny dark green above with a white felty surface below, making an interesting colour contrast. The leaves are exceptionally large with a length of up to 36 cm and width of 15 cm. Emerging leaves are short, fat and densely and completely felted with soft white hairs.

Often mistakenly thought of as being part of the Protea family, Oldenburgia grandis' thistle-like flowers indicate that it belongs in the Daisy Family. The flower-head broadens as it matures to expose the nut-like fruits which are thin, brown and have a tuft of long, pale hairs at the tips. Flowering takes place irregularly throughout the year, often with an increase of flowers in autumn.

The dense silvery hairs on the young leaves and shoots protect them from sun and wind damage. The corky bark is fire resistant and the plant has the capacity to re-sprout after a fire.

Oldenburgia grandis is potentially threatened by habitat loss in some areas. It has a geographic range of only 500 km² and very specific habitat needs which further limit its prevalence.

The leaves of Oldenburgia arbuscula are reportedly poisonous so it is safer to assume that the leaves of this species may also be poisonous.

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Flowers

Description

Flowers are large, 12 cm in diameter, and bear a resemblance to those of an artichoke or a giant thistle. The solitary heads are held on tall, thick, densely felted, branched stems which arise from the center of the rosette of leaves.

Season

All Year Plants will seldom bloom for the entire season as given in the list, but should flower during a period within these parameters.
Autumn Plants will seldom bloom for the entire season as given in the list, but should flower during a period within these parameters.

Colour

lavender
purple

Growth Rate

Slow Specifying growth rate can be very misleading as there is considerable variation of growth rate depending on type and species of plant, available water, supplementary feeding, mulching and general care, as well as the plants suitability and adaptability to the garden environment.

Plant Uses

Accent or Focal Point A plant used to attract the attention because of its colour or form.
Attracts bees, butterflies or other insects This plant attracts insects which can be food for birds or other creatures in your garden.
Attracts Birds This plant will attract birds.
Rock Garden An area constructed of larger rocks, arranged naturally, to emphasise the use of stones as a main element. Generally plants used do not need a lot of care.
Wild Garden An indigenous garden planted for the benefit of wildlife and birds. Provides food, water, a variety of mini-biomes and no poisonous chemicals are used.

Distribution and Habitat

Oldenburgia grandis is endemic to a small area in the Eastern Cape, from the Suurberg Mountains to Grahamstown, in acidic soil on sandstone and quartzite outcrops.

Planting Suggestions

Oldenburgia grandis is suited to rocky areas in full sun with good ventilation but also performs well in composted, acidic, sandy loam. This species needs to be watered moderately when in growth and kept dry in winter. Minimum winter temperatures are 7-10 º C. The tree will survive lower temperatures but where light frost conditions are experienced, the plant must be protected during winter.

Oldenburgia grandis can be propagated from seed but these have a very low germination rate. Semi-hard cuttings in sand are purportedly more successful. The difficulty is in attaining material as this plant is not available in nurseries and is rarely seen in gardens.

The old method of digging a deep hole and filling it with soil and compost has resulted in many trees failing to thrive, dying, rotting at the base or worse still, falling over in later years due to poor root development. Refer to the following sites for the best method of planting trees:

Treehelp.com: Planting a tree

International Society of Arboriculture: New Tree Planting

Tree People: Plant the right way

For those of you who have a clay problem try:

Rod's Garden: Planting in clay soil

Lorraine's Garden Notes

References:

COATES-PALGRAVE, M. 2002. Keith-Coates Palgrave Trees of southern Africa, 3rd edn., 2nd imp. Struik Publishers, Cape Town.

JOHN MANNING AND COLIN PATERSON-JONES. 2004. South African Wild Flowers: Jewels of the Veld, Struik Publishers, Cape Town.

PlantZAfrica.com: Plants of Southern Africa: Oldenburgia grandis

Wikipedia: Oldenburgia grandis

Swart, Carin (2008) Life history, population dynamics and conservation status of Oldenburgia grandis (Asteraceae), an endemic of the Eastern Cape of South Africa. Masters thesis, Rhodes University.