Peppermint

Mentha x piperita L.

A cross between the native Mentha aquatica and introduced Mentha spicata (Spearmint)
There are 2 variants that are naturalised, Mentha x piperita var. piperita (Peppermint) and Mentha x piperita var. citrata (Eau-de-Cologne Mint or Lemon Mint).

Order: Lamiales

Family: Lamiaceae

Names:

Mentha is the Latin name for mint and comes from the name of the Greek nymph, Minthe, who was changed into the mint plant.

Piperita
Peppermint

Other Names:

Eau de Cologne Mint.

Summary:

A strongly aromatic, almost hairless, perennial herb with purple flowers and opposite, toothed leaves.

Description:

Cotyledons:

Two.

Leaves:

Opposite.
Stipules -
Petiole - 3-18 mm long.
Blade - Egg shaped to elliptic, 15-70 mm long x 10-30 mm wide, with a pungent “Peppermint” odour in var. piperita.
Egg shaped to lance shaped, 15-90 mm long x 10-37 mm wide, with a softer “Eau-de-Cologne” aroma in var. citrata.
Toothed edges, aromatic. Tip pointed or rarely obtuse. Hairless or almost so or slightly rough to touch. Glandular aromatic. Tapered base.

Stems:

Erect, 500-1000 mm tall, aromatic. Branches bending upwards and often tinged with purple. Hairless or almost so.
Frequently forms roots at the nodes where they touch the ground. Stoloniferous.

Flower head:

Cylindrical and spike like, 30-60 mm long with the flower clusters becoming separated in var. piperita.
Globular, short, broad, dense, terminal spike, 15-30 mm long x 12-20 mm diameter with many flowers in var. citrata.
Floral leaves reduced to bracts.

Flowers:

Strongly aromatic.
On stalks (pedicels) 2-3 mm long.
Ovary -
Calyx - Bell shaped, tubular, cylindrical, 3-5 mm long, 10-12 ribbed (veined), smooth and hairless except on the teeth. Tube 2-3 mm long, lobes, triangular and similar sized, 1-1.5 mm long, smooth or slightly rough to touch. Scattered hairs on the medial ridge and lobes often have fine hairs. Conspicuous oil glands.
Petals - Purple, sometimes spotted, 5-6.5 mm long, smooth, oblong lobes with rounded tips.
Stamens - Inside the flower. Filaments 1-1.5 mm long.
Anthers - 0.5 mm long. Contained within the flower (included) in var. piperita (Peppermint) or stick out from the flower (exerted) in var. citrata (Eau-de-Cologne Mint).

Fruit:

Pale brown, smooth nutlet. It is rarely developed in this cross.

Seeds:

None formed. It is a sterile hybrid.

Roots:

Rhizomes and stolons.

Key Characters:

Purple flowers in clusters.
Glabrous herb with occasionally a few scattered short hairs, especially along the stems.
Basal leaves stalked or petiolate.
Inflorescence of false whorls forming terminal cylindrical or globose spikes.
Whorls many flowered.
Floral leaves reduced to narrow bracts.
Calyx 3-5 mm long.
Calyx lobes one third the length of the calyx.
Calyx 10 veined.
No fruit produced.
Adapted from J.M. Black, Judy Wheeler and B.J. Conn and John Moore

Biology:

Life cycle:

Perennial

Physiology:

Reproduction:

By rhizomes.

Flowering times:

Summer in SA.
March in Perth.
December to May in NSW.

Seed Biology and Germination:

Vegetative Propagules:

Hybrids:

Allelopathy:

Population Dynamics and Dispersal:

Spread by rhizomes.

Origin and History:

Europe.
Introduced as a crop plant.

Distribution:

ACT, NSW, SA, TAS, VIC.

Blue = Mentha X piperita. Red = Mentha piperita.
Courtesy Australia's Virtual Herbarium.

Habitats:

Climate:

Cool temperate. High rainfall areas around 400 latitude.

Soil:

Prefers wet areas.

Plant Associations:

Significance:

Beneficial:

Used for food and oils.
Oil extracted from leaves by steam distillation and used for flavouring confectionery, pharmaceutical products and foods.

Detrimental:

Toxicity:

Not recorded as toxic.

Legislation:

None.

Management and Control:

Thresholds:

Eradication strategies:

Herbicide resistance:

Biological Control:

Related plants:

There are 2 variants or nothomorphs that are naturalised, Mentha X piperita var. piperita (Peppermint) and Mentha X piperita var. citrata (Eau-de-Cologne Mint or Lemon Mint).

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). P732.

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

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

Reid, R.L. (1990) The Manual of Australian Agriculture. (Butterworths, Sydney). P114.

Acknowledgments:

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