Japanese peppermint

Japanese peppermint is distributed to temperate regions in East Asia.   Japanese natural menthol had dominated the world market, before menthol was synthesized.   Therefore, this plant is called Japanese Peppermint.

This plant grows in sunny marsh areas and sunny banks of stream.   It expands the subterranean stem in all directions to propagate very well and sometimes to grow in clusters.   The stem is squared and has soft hairs.   It branches at its base and grows from 50 to 60 cm in height.   The leaf is decussate** and oblong-ovate or oblong-elliptical with pointed tip and large serrations.  Both sides are hairy.   The number of oil gland is larger on the under side than on the upper side.   The whole plant, especially the flower and the leaf release a fresh scent.  It tastes like mint when tasting the leaf.

In August and September, many labiate flowers bloom in a circular manner at the leaf axils of the upper part of the stem.   The corolla is light purple, four to five millimeters in length and splits into 4 parts.   The calyx tube is divided into 5 parts which are sharply pointed at their tip.

Oil of Japanese Mint is the essential oil obtained through the process of steam distillation of this plant, which is then cooled down to remove the dissolved solid.   It contains menthol of more than 30%.   The oil of Japanese mint and l - menthol are used as a cooling compound or refreshing flavor for foods, daily commodities, cigarettes and medicines.

* l - menthol activates the cool thermoreceptor on the sensory neurons to provide a refreshing feeling.   Whereas capsaicin activates the hot thermoreceptor on the sensory neurons to provide a hot feeling.

** Alternating in pairs at right angles.

Classification: Lamiaceae Mentha
Scientific name: Mentha arvensis var. piperascens
Japanese name: Hakka
English Name: Japanese peppermint
Native locality: East Asia
Ecological description: Perennial
RDB : ---
Planting place: Yayu-en
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