Small-flowered Onion Grass

Romulea minutiflora Klatt

Synonyms -

Family: Iridaceae

Names:

Other Names:

Summary:

A wiry, cylindrical leaved, purple flowered plant with squarish packets of seed. It has annual tops with a perennial underground corm.

Description:

Cotyledons:

One.

First leaves:

Narrow, cylindrical, <2 mm diameter, stiff, leathery

Leaves:

5-12 all arising from the base.
Blade - 20-150 mm long x 1-2 mm wide. shiny, wiry, parallel sided. Double grooved along the side with rounded edges.
No auricles or ligule because it is not a true grass.

Stems:

None.
Flower stem - Slender, about half the length of the leaves, 10-60 mm long x 1 mm wide.

Flower head:

2-4 flowers per plant. Flowers single on short, stout, slightly curved stalks.

Flowers:

Purple with a yellow throat. 10-15 mm diameter.
Ovary -
Petals - 6, short, to 9 mm long. Pale purple with a yellow throat. Slightly exceed the enclosing membranous sheath.
Stamens -
Anthers - Yellow.

Fruit:

Rectangular, 3 celled capsule, 5-8 mm long.

Seeds:

Brown, globular, 1-2 mm diameter, flattened or somewhat angular. Surface dimpled, grooved and hairless.

Roots:

Pinkish, small, vase to egg shaped corm with winged protuberances at the base.

Key Characters:

Cylindrical, wire-like leaves.
Purple, 6 petalled flowers with a yellow throat.
Rectangular fruit.
Underground, egg shaped corm with protuberances.

Biology:

Life cycle:

Annual tops with a perennial corm. Seeds and corms germinate in autumn to winter and grow over winter to produce new corms and flowers in spring. Top growth dies off with the onset of summer.

Physiology:

Reproduction:

By seed and corms.

Flowering times:

Spring in western NSW.

Seed Biology and Germination:

Vegetative Propagules:

Corms.

Hybrids:

Allelopathy:

Population Dynamics and Dispersal:

Spread by seed and corms.

Origin and History:

South Africa.

Distribution:

ACT, NSW, NT, SA, VIC, WA.

Courtesy Australia's Virtual Herbarium.

Habitats:

Climate:

Temperate.

Soil:

Clay and clay loams
Often associated with compacted soils.

Plant Associations:

Wandoo woodlands, Black box communities.
Prefers overgrazed areas.

Significance:

Beneficial:

Corms eaten by Galahs and other birds.

Detrimental:

Low palatability
Weed of crops, pastures, lawns, gardens, roadsides, disturbed areas.

Toxicity:

May cause fibre balls in the stomachs and bowels of cattle, horses and sheep.
Suspected of causing infertility, abortion and paralysis of romulosis in sheep and may be caused by a leaf spot fungus (Helminthosporium biseptatum) associated with Onion Grass.

Symptoms:

Few apart from chronic scouring in cattle.

Treatment:

Laxatives tend to be of little use. Surgery is performed on valuable animals.
Feed hay or alternative fibre when pasture is lush in infested paddocks or remove stock when they start to eat quantities of Onion Grass.

Legislation:

None.

Management and Control:

Summer cultivation to expose and desiccate corms provides some control. Chlorsulfuron, metsulfuron, glyphosate, imazapyr and imazethapyr provide reasonable control in various cropping situations. In pastures, late applications of glyphosate provides some suppression and imazethapyr can provide control in legume pastures. Deep rip soil if compacted.
In lawns metsulfuron provides good control or mowing with a rotary mower every 2 weeks for a few years will eventually exhaust the corm.
In cropping areas, spray with glyphosate, cultivate, then plant a cereal and treat with chlorsulfuron.

Thresholds:

Eradication strategies:

Apply a mixture of 500 mL of glyphosate plus 5 g chlorsulfuron plus 250 mL Pulse® per 100 L water in winter before flowering. Repeat annually for 2-3 years. Cultivate over summer If possible to expose corms. Deep rip soil if compacted. Plant vigorous perennial species.

Herbicide resistance:

None reported.

Biological Control:

Related plants:

Onion Grass (Romulea rosea) has larger flowers and a globular, white bulb with no protuberances.
Romulea flava has yellow flowers.
Romulea obscura has orange flowers.

Plants of similar appearance:

Thread Iris, Cape Tulip, Annual Ryegrass, Barley grass, Brome grass, Darnel, Fountain grass, Quaking grass, Sand fescue, Silver grass, Volunteer Cereals, Wild Oats, Toad Rush, Winter grass.

References:

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

Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P193. Photo.

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

Harden, Gwen J. (1991). Flora of NSW. (Royal Botanic Gardens, Sydney). Volume . P. Diagram.

Hussey, B.M.J., Keighery, G.J., Cousens, R.D., Dodd, J. and Lloyd, S.G. (1997). Western Weeds. A guide to the weeds of Western Australia. (Plant Protection Society of Western Australia, Perth, Western Australia). P34.

Lamp, C. and Collet, F. (1990). A Field Guide to Weeds in Australia. (Inkata Press, Melbourne).

Lazarides, M. and Cowley, K. and Hohnen, P. (1997). CSIRO handbook of Australian Weeds. (CSIRO, Melbourne). #861.4.

Moerkerk, M.R. and Barnett, A.G. (1998). More Crop Weeds. R.G. and F.J. Richardson, Melbourne. P21. Diagrams. Photos.

Acknowledgments:

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