Topped Lavender

Lavandula stoechas L.

Family: Lamiaceae.

Names:

Lavandula is from the Latin words for 'violet' and 'to wash' and refers to the flower colour and the practice of adding perfumed lavenders to ancient soaps.
Topped Lavender refers to the purple showy bracts on top of the flower head.

Other names:

French Lavender
Bush Lavender
Italian Lavender
Spanish lavender

Summary:

Topped Lavender (Lavandula stoechas) is a perennial, aromatic, many-stemmed, erect, furry shrub to 0.3-1 m high and wide with greyish foliage. The crowded leaves are opposite, narrowly oblong with the margin often curved under, 8-30 mm long, shortly hairy and strongly fragrant when crushed. The flowers are arranged in a dense cylindric to 4-sided spike which is topped by large showy petal-like violet bracts. The individual flowers, which are clustered below the terminal bracts, are usually dark purple but occasionally pink or white, 6-8 mm long and tubular with 2 broad spreading lips. The fruit is composed of 4 tiny nutlets.
Topped Lavender is native to the Mediterranean. It is frequently cultivated as an ornamental or for its oil, and has now become a weed of roadsides, drainage lines, poor pasture and disturbed areas. It flowers from July to November.

Description:

Cotyledons:

Two.

Leaves:

Opposite and paired or clustered at the nodes. Fragrant when crushed.
Stipules - None.
Petiole - None.
Blade - Grey-green, parallel sided to oblong, 8-30 mm long x 1.5-10 mm wide. Dense short hairs (star type). Edges turned down but with no teeth or lobes.

Stems:

Many, 300-600(1000) mm long, greyish, branched, square when young, often grow along the ground then bend upwards. Densely hairy with star type hairs. Lower parts woody and rough.
Coppice when cut.

Flower head:

Dense quadrangular spike, 13-50 mm long x 8-15 mm wide at the ends of stems. A tuft of 3-5, large, 5-20 mm long, violet, oval or fan shaped, sterile, papery bracts with obvious veins are on top of the flower head.

Flowers:

Produce abundant nectar.
Bracts - Floral bracts broadly egg shaped, up to 6 mm long x 7 mm wide with 3 shallow lobes, obvious veins, hairy. Bracteoles are egg shaped, 0.5 - 2 mm long, hairy.
Ovary - Superior. Styles with 2 short lobes
Calyx - 4-6 mm long, tubular, 13 ribbed. Dense star hairs. 5 lobed and the back lobe is broader and has a notched appendage near the top.
Corolla - Dark purple, rarely white or pink, tubular, 6-8 mm long. 2 lipped. Upper lip has 2 lobes and lower lip has 3 circular lobes.
Stamens - 4 inside the corolla tube, the front pair is longer.
Anthers - Yellow, kidney shaped, small, and one celled.

Fruit:

Pale brown with many dark spots, shiny, triangular nutlet about 2 mm diameter. Hairless.

Seeds:

Small.

Roots:

Woody. Shallow and spreading.

Key Characters:

Leaf margins entire. Calyx 8-9 mm long, the lobes all equal.
Leaves strongly scented and grey green.
Stems square when young and with star type hairs.
Purple bracts as 'flowers'.
Shrub to ~1 m high and wide.

Biology:

Life cycle:

Seed germinates at any time of the year and grow slowly. They are semi dormant but evergreen in summer and autumn and grow in winter and spring. Flowering occurs from July to November with seeds produced in spring and summer. Plants are at least 2 years old before they flower.

Physiology:

Reproduction:

By seed.

Flowering times:

July to November in SA.
Winter and spring in WA.

Seed Biology and Germination:

Seed has a long dormancy in soil.

Vegetative Propagules:

Crowns and root fragments.

Hybrids:

Allelopathy:

Population Dynamics and Dispersal:

The main spread is from intentional planting in gardens and consequent escape. Water, wind and birds spread seed.
Perennial roots and crowns are moved by cultivation equipment and in gravel for road making. They coppice when stems are cut.
In suitable areas the infestation increases in density until few other plants remain.

Origin and History:

Mediterranean.
Introduced as a garden plant in the 1850's.
Naturalised in Victoria by 1893 and proclaimed a noxious weed in 1920.

Distribution:

NSW, SA, VIC, WA.

Courtesy Australia's Virtual Herbarium.

Habitats:

Climate:

Humid and sub humid warm temperate regions with mainly winter rainfall.

Soil:

Occurs on a range of soil types.

Plant Associations:

Poor and neglected pastures.

Significance:

Beneficial:

Oil of lavender is extracted from the leaves and used for perfume, varnish on paintings and room fresheners.
Used in paint.
Honey plant.
Medicinal plant used for asthma, chest ailments and cramp.
Ornamental.

Detrimental:

A weed of roadsides, streams, drainage lines, disturbed areas and poor pasture.
In pastures it forms dense patches excluding other species and providing shelter for rabbits.
It is rarely eaten by stock.

Toxicity:

Not recorded as toxic.

Legislation:

Noxious weed of Victoria.

Management and Control:

Individual plants can be manually removed providing the main roots are also removed. Larger areas can be ploughed in spring and repeated as new seedling or shoots emerge. Crowns and root fragments will re shoot. Competitive pasture species should be sown to reduce reinfestation by seedlings that will emerge for a number of years. Mowing and slashing are ineffective because the plants readily regrow. It is tolerant to hormone herbicides.

Thresholds:

Eradication strategies:

Individual plants can be removed manually providing the main roots are also removed. Crowns and root fragments should be burnt. Larger areas can be ploughed in spring and repeated as new seedling or shoots emerge. Crowns and root fragments may reshoot. Competitive pasture species should be sown to reduce reinfestation by seedlings that will emerge for a number of years. Mowing and slashing can kill some plants and reduce the density of the infestation. A hot fire in autumn can provide control of the older bushes but must be followed by a program to control seedlings that emerge after fire. Mature plants often regrow after cool fires. Cultivation usually provides good control.
Small areas can be cut close to ground and the cut stem painted immediately with neat glyphosate(450g/L). Hand spray larger areas with 200 mL Garlon® or 2,4-D ester(800g/L) in 10 L diesel.
It is relatively tolerant to overall sprays of glyphosate.
Grazing is not effective and heavy grazing may make the infestation worse.

Herbicide resistance:

Biological Control:

Related plants:

English Lavender (Lavandula angustifolia) has a more elongated flower spike and lacks the showy bracts.
French Lavender (Lavandula dentata) has finely toothed leaves.
Lavender (Lavandula vera)

Plants of similar appearance:

Mints, Mintweed, Pennyroyal, Horehound, Sages, Marjoram, Basil, Rosemary, Spearmint, Hyssop, Thyme, Salvia, Stachys, Lions Ear.

References:

Auld, B.A. and Medd R.W. (1992). Weeds. An illustrated botanical guide to the weeds of Australia. (Inkata Press, Melbourne). P179. Photo.

Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P732. 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). P168-169. Photo.

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

Lazarides, M. and Hince, B. (1993). CSIRO handbook of economic plants of Australia. (CSIRO, Melbourne). #727.2.

Marchant, N.G., Wheeler, J.R., Rye, B.L., Bennett, E.M., Lander, N.S. and Macfarlane, T.D. (1987). Flora of the Perth Region. (Western Australian Herbarium, Department of Agriculture, Western Australia). P562.

Moore, J.H. and Wheeler, J.R. (2008). Southern Weeds and their Control. (Second Edition). Department of Agriculture and Food Western Australia. P184-185. Photos.

Parsons, W.T. and Cuthbertson, E.G. (1992). Noxious weeds of Australia. (Inkata Press, Melbourne). P493-4. Photos

Acknowledgments:

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