An erect, many branched, annual to 1 metre tall with slender, alternate leaves and 5 petalled, 20 cm wide blue flowers from October to November. It is used to make linen and linseed oil.
Description:
Cotyledons:
Two. Oval. Tip flat or slightly indented. Edges smooth. Base tapered. Hairless. Surface dull. No petiole.
First leaves:
Opposite in pairs. Oval to spear shaped. Tip pointed. Edges smooth. Base tapered. Hairless. No petiole.
Leaves:
Alternate.
Stipules - Absent or inconspicuous.
Petiole - None.
Blade - Bright to yellow green, parallel sided to narrowly oval, 15-45 mm long by 1-6 mm wide, soft. Acute tip. Hairless.
Stems:
Erect, hairless, slender, to 1000 mm tall, unbranched or branched near the top. Bark smooth, tough and fibrous.
Flower head:
Loose corymb, many branched cymes at the ends of stems.
Flowers:
Blue or rarely white or pale pink, 20 mm wide. Bisexual.
Ovary - Superior. 5 styles free nearly to the base.
Sepals - 5 Egg shaped, 5-9 mm long, keeled near the base, obvious midrib with 2 paler side veins about half as long, pointed tip. Edges membranous and sometimes with tiny hairs.
Petals - 5, Blue or rarely white or pale pink, 11-13 mm long, egg shaped, clawed, overlapping.
Stamens -
Anthers - 2 celled, opening by a lengthwise slit.
Nectary glands between petals and stamens.
Fruit:
Almost globular, 5 celled capsule, rounded, thin walled, 5-8 mm long by 7-10 mm wide, longer than the sepals. Tip abruptly pointed. 2 seed per cell, 10 seeds per fruit. Sepals remain attached to the fruit.
Seeds:
Light brown, 4-5 mm long by 3-4 mm wide by 1-2 mm thick, shiny, flattened. Tip round, Edges smooth. Base pointed to round.
Roots:
Taproot.
Key Characters:
Annual.
Flowers blue.
Petals 8-13 mm long.
Sepals ovate, acuminate, 5-9 mm long, midrib prominent between lateral nerves about half as long.
Styles free except at the base.
Capsule 7-10 mm across.
From J.R. Wheeler and N.T. Burbidge.
Biology:
Life cycle:
Annual. Seed is planted in autumn to early winter and the crop grows in winter and spring to be harvested in early summer.
Physiology:
Sensitive to frost at flowering.
Reproduction:
By seed.
Flowering times:
Spring to summer in western NSW.
October to November in Perth.
Seed Biology and Germination:
Vegetative Propagules:
Hybrids:
There are a number of varieties. Glenelg is the most widely grown and Croxton is more tolerant to Fusarium wilt.
Different cultivars are grown for flax and linseed.
Cultivated for its fibre that is used to make linen and its seeds, from which linseed oil is extracted. Linseed meal used as a high protein supplement for stock.
Detrimental:
Weed of roadsides, railways, winter crops, disturbed areas.
Toxicity:
Toxic
Linseed cake, young crops, screenings, flowers, seeds and wilted plants can be toxic to stock causing cyanide poisoning.
Young plants are most toxic. Tends to be more toxic in warmer climates.
Toxicity of cake depends on method of oil extraction and preparation of the cake. Cake made by hot pressing is rarely toxic.
Symptoms:
HCN toxicity.
Treatment:
Don't allow hungry animals to graze young crops. Keep linseed meal levels in rations low.
Prompt action is required if poisoning occurs.
Legislation:
None.
Management and Control:
Good weed control is required because Linseed is a poor competitor.
Thresholds:
Eradication strategies:
Herbicide resistance:
Biological Control:
Sensitive to Fusarium wilt, Pasmo and rust. Varieties like Croxton are tolerant to Fusarium.
Red Legged Earth Mite, Cutworms and Heliothis caterpillars are the main pests.
Related plants:
French Flax (Linum trigynum) has smaller, 6 mm, yellow flowers.
Purging Flax (Linum catharticum)
Wild Flax (Linum marginale) is a native species and has united styles.
Yellow Flax (Linum flavum)
Plants of similar appearance:
References:
Auld, B.A. and Medd R.W. (1992). Weeds. An illustrated botanical guide to the weeds of Australia. (Inkata Press, Melbourne). P182-183. Photo.
Burbidge, N.T. and Gray, M. (1970). Flora of the Australian Capital Territory. (Australian National University Press, Canberra). P238.
Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P436-437. Photo.
Everist, S.L. (1974). Poisonous Plants of Australia. (Angus and Robertson, Sydney). P511-513.
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). P172-173. Photo.
Lazarides, M. and Hince, B. (1993). CSIRO handbook of economic plants of Australia. (CSIRO, Melbourne). #750.5.
Marchant et al (1987). Flora of the Perth Region. (Western Australian Herbarium, Department of Agriculture, Western Australia). P463.
Moerkerk, M.R. and Barnett, A.G. (1998). More Crop Weeds. R.G. and F.J. Richardson, Melbourne. P104. Diagrams. Photos.
Reid, R.L. (1990) The Manual of Australian Agriculture. (Butterworths, Sydney). P111.
Acknowledgments:
Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.