Spearmint

Mentha x spicata L.

Synonyms - Mentha viridis. Mentha x spicata.
Possibly a hybrid between Mentha longifolia and Mentha rotundifolia.

Order: Lamiales

Family: Lamiaceae

Names:

Mentha
Spicata
Spearmint

Other Names:

Summary:

A large, erect, perennial aromatic herb with stalkless, oval, pointed, toothed leaves and many purple flowers in rings on terminal spikes.

Description:

Cotyledons:

Two.

Leaves:

Opposite, paired. Strong, sweet or pungent aroma.
Stipules -
Petiole - None or almost none.
Blade - Narrowly egg shaped to elliptical, 19-80 mm long x 6-30 mm wide, smooth or rough to touch, pointed tip, sharply toothed edges. Hairless or sparsely hairy. Obvious veins.

Stems:

500-1000 mm long. Strong, sweet or pungent aroma. Almost hairless.

Flower head:

Long narrow, cylindrical spike, not very dense near the base, 40 -90 mm long at the end of the stem, with many clusters of flowers, 6-10 mm diameter, in rings around the axis. Floral leaves reduced to bracts.

Flowers:

Purple, pink, white or purple spotted. Many on stalks (pedicels) 1-2 mm long.
Ovary -
Calyx - Bell shaped, 1-2 mm long, with triangular lobes 0.5-1 mm long. Tubular section with tiny glandular or non glandular hairs and sometimes with oil gland dots on the surface. Lobes may have tiny hairs.
Perianth -
Sepals -
Petals - Purple, pink, white or spotted with purple. 2.5-4 mm long, with egg shaped lobes with tips that are flat, obtuse or notched.
Stamens - Stick out of the flower. Filaments 2.5-3 mm long.
Anthers - Less than 0.5 mm long.

Fruit:

Network veined or smooth nutlet.

Seeds:

Roots:

Spreading rhizomes up to 1000 mm long.

Key Characters:

Minty aroma.
Opposite toothed leaves.
Purple, pink, white or purple spotted flowers in rings around the stem.

Biology:

Life cycle:

Perennial herb.

Physiology:

Reproduction:

Flowering times:

Summer in SA.
December to February in Perth.
Summer in WA.

Seed Biology and Germination:

Vegetative Propagules:

Hybrids:

Allelopathy:

Population Dynamics and Dispersal:

Spread mainly by intentional planting and rhizome growth.

Origin and History:

Northern Mediterranean. Europe.

Distribution:

ACT, NSW, SA, TAS, VIC, WA.
Naturalised in SA, WA.

Courtesy Australia's Virtual Herbarium.

Habitats:

Climate:

Temperate. Mediterranean.

Soil:

Prefers damp soils.

Plant Associations:

Significance:

Beneficial:

Food. Oils.
Cultivated culinary herb.

Detrimental:

Weed of streams, swamps and damp disturbed areas.

Toxicity:

Not recorded as toxic.

Legislation:

None.

Management and Control:

Thresholds:

Eradication strategies:

Herbicide resistance:

Biological Control:

Related plants:

Apple Mint (Mentha X rotundifolia)
Eau-de-Cologne Mint (Mentha X piperita var. citrata)
Native Pennyroyal (Mentha satureioides)
Peppermint (Mentha X piperita)
Pennyroyal (Mentha pulegium)
River Mint (Mentha australis)
Slender Mint (Mentha diemenica)
Spearmint (Mentha spicata)
Mentha aquatica
Mentha suaveolens

Plants of similar appearance:

References:

Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P731. Diagram.

Burbidge, N.T. and Gray, M. (1970). Flora of the Australian Capital Territory. (Australian National University Press, Canberra). P312.

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). P170.

Lazarides, M. and Hince, B. (1993). CSIRO handbook of economic plants of Australia. (CSIRO, Melbourne). #815.9.

Marchant et al (1987). Flora of the Perth Region. (Western Australian Herbarium, Department of Agriculture, Western Australia). P563.

Acknowledgments:

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