Diosma

Coleonema album (Thumb.) Bartling & H.L. Wendland

Synonyms - Diosma album

Family: - Rutaceae

Names:

Coleonema
Album refers to the white or pale flowers.

Other Names:

Summary:

A compact, many branched, fragrant, shrub 0.5-2 m tall and round with many, small white 5 petalled flowers and fine, sharply pointed, crowded leaves.

Description:

Cotyledons:

Two.

First leaves:

Leaves:

Alternate, crowded, almost erect.
Stipules - none.
Petiole - Short
Blade - Parallel sided, with clear dots that are oil glands. 5-10 mm long by 1 mm wide. Flat to concave on top, keeled underneath. Tip pointed with a fine sharp spine. Base tapering. Sides parallel, translucent and smooth to very finely toothed. Hairless but fine teeth on leaf margins look like hairs.

Stems:

Many woody branches with drooping branchlets that are covered with fine straight hairs.

Flower head:

Flowers single of in small clusters in leaf axils and surrounded by small sharp bracts.

Flowers:

White to light pink, 10-12 mm wide, symmetrical on short 1mm stalks (pedicels). Bisexual.
Ovary - 5 cells
Style - Short, united from the base and appears simple.
Stigma - 5 lobed, head like.
Sepals - Egg shaped, 2 mm long, tip pointed, edges translucent and hairy.
Petals - 5, white to light pink, spoon shaped, 5 mm long, overlapping, narrowed into a lengthwise channelled claw at the tip. Tip obtuse with a sharp flexible point
Stamens - 5 of similar length with anthers in a single ring, attached to the outer edge of the disk. 5 without anthers (staminodes) hidden in the claw of the petals. Filaments - tapering to a fine point. 2-3 mm long for those with anthers and 1-2 mm long for ones without anthers.
Anthers - 1 mm, oblong with a gland at the tip.
Bracts - 6-8, egg shaped, with pointed tips, hairy edges and pressing closely on the sepals

Fruit:

5 segments, hairless, flattened, rough and horned at the tip

Seeds:

Roots:

Taproot with many laterals.

Key Characters:

Leaves mucronate and keeled below.
5 fertile stamens
Staminoidal filaments concealed in the longitudinal channels of the petals.
Adapted from J.R. Wheeler.

Biology:

Life cycle:

Perennial shrub.

Physiology:

Reproduction:

By seed.

Flowering times:

June-September in WA.

Seed Biology and Germination:

Vegetative Propagules:

None.

Hybrids:

Pink, white dwarf forms are sold by nurseries.

Allelopathy:

Population Dynamics and Dispersal:

Origin and History:

South Africa.

Distribution:

WA.
Spreading around Australind, Ludlow, Esperance, Mandurah and Harvey.

Courtesy Australia's Virtual Herbarium.

Habitats:

Climate:

Mediterranean.

Soil:

Prefers sandy soils.

Plant Associations:

Tuart forest.

Significance:

Beneficial:

Widely planted ornamental.

Detrimental:

Minor environmental weed.

Toxicity:

None reported.

Symptoms:

Treatment:

Legislation:

None.

Management and Control:

Thresholds:

Not an agricultural weed.

Eradication strategies:

Manually remove isolated bushes.
Spray until just wet with 10 mL glyphosate (450 g/L) or Grazon or Garlon plus 2.5 mL Pulse penetrant in 1 L water.

Herbicide resistance:

None reported

Biological Control:

None

Related plants:

No other species in this genus in WA.
Boronias
Citrus

Plants of similar appearance:

References:

Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P492.

Bodkin, F. (1986). Encyclopaedia Botanica. (Angus and Robertson, Australia).

Everist, S.L. (1974). Poisonous Plants of Australia. (Angus and Robertson, Sydney).

Lazarides, M. and Cowley, K. and Hohnen, P. (1997). CSIRO handbook of Australian Weeds. (CSIRO, Melbourne). 265.1.

Marchant et al (1987). Flora of the Perth Region. (Western Australian Herbarium, Department of Agriculture, Western Australia). P486.

Paczkowska, G. and Chapman, A. (2000). The Western Australia flora: a descriptive catalogue. (Wildflower Society of Western Australia (Inc), the Western Australian Herbarium, CALM and the Botanic Gardens & Parks Authority). P521.

Randall, J.M. and Marinelli, J. (1996) Invasive Plants. (Brooklyn Botanic Gardens Inc. Brooklyn). P. Photo.

Wheeler, Judy, Marchant, Neville and Lewington, Margaret. (2002). Flora of the South West: Bunbury - Augusta - Denmark. (Western Australian Herbarium, Bentley, Western Australia). P875. Diagram.

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.