Asarum asaroides
Asarum asaroides was introduced to Europe by the German, Philipp von Siebold, on his return from Japan in 1830.
Species Information
- Scientific Name: Asarum asaroides (C.Morren & Decne.) Makino
- Synonym(s): Asarum thunbergii
- Conservation Status: Not Evaluated according to IUCN Red List criteria.
- Habitat: Woodlands; often growing in deep shade, in valleys or ravines and on north-facing hillsides.
- Key Uses: Ornamental, food.
- Known hazards: None known.
Taxonomy
- Class: Equisetopsida
- Subclass: Magnoliidae
- Superorder: Magnolianae
- Order: Piperales
- Family: Aristochiaceae
- Genus: Asarum
About this species
Asarum is a genus (a group of related species) of perennials with underground stems (rhizomes). It occurs across the temperate regions of the northern hemisphere, with the highest concentration of species in China and Japan. Their usually evergreen, long-stemmed leaves can be attractively patterned and the curious, sometimes sinister-looking flowers appear from beneath them, borne on short stalks. The flowers are commonly in shades of dull purple, brown or green.
Taken in its broadest sense, the genus Asarum (wild ginger) contains around 100 species, but in the past it has been split into several smaller genera, separated by minor differences in the flowers. The genus Heterotropa was established by the Belgian botanists Charles Morren and Joseph Decaisne in 1834, and they described one species, H. asaroides, based on the plant incorrectly named Asarum virginicum in Carl Peter Thunberg's Flora Japonica (1784). It was renamed Asarum asaroides by Tomitaro Makino in 1910.
Geography & Distribution
Around 50 species of Asarum grow in Japan and the Ryukyu Islands, many of them found only there. They include A. asaroides, which occurs in south-west Honshu and Kyushu.
Description
The spotted and mottled leaves are broadly ovate (egg-shaped) to roughly triangular in outline and up to 12 cm long. They persist throughout much of the year but the main growing period is during spring and summer.
The dull, dark purplish-green flowers appear in early spring, and have a pear-shaped tube 2–2.5 cm long, and three spreading, rounded to triangular lobes. Around the mouth of the tube, the perianth (sepals and petals) lobes are wrinkled, these ridges being lighter purple or crested with white. The flowers have also been described as 'perfumed somewhat like a ripe apple’ and ‘large as a walnut’.
Uses
Asarums have been cultivated in Japan for hundreds of years. Some believe they offer protection from earthquakes and storms if planted at the front of houses or hung from the eaves.
Cultivation
Although Asarum asaroides can tolerate a few degrees of frost, it is best grown in a cold frame to keep off rain in the winter and provide some protection during particularly cold spells. Use an acidic, humus-rich, free-draining soil mix and place the rhizomes just below soil level. During the winter keep the soil just moist but once growth begins in spring, increase watering and never let the soil dry out throughout spring and summer. If this species is tried in the open garden, plant it in a cool, shady, sheltered spot.
This is a slow-growing plant but older clumps can be carefully divided in spring, by cutting off portions of the rhizome with roots and a growing point. If seed is produced it should be collected and sown immediately, before it dries out. Germination will usually occur in early spring but may take over a year.
This species at Kew
Asarum asaroides can be seen in the Davies Alpine House at Kew when in flower.
Spirit-preserved of Asarum asaroides are held in Kew’s Herbarium, where they are available to researchers, by appointment. The details of one of these can be seen on-line in the Herbarium Catalogue.
References and credits
Beentje, H. (2010). The Kew Plant Glossary. Royal Botanic Gardens, Kew.
Boyce, P. (1994). Two Asian Asarum species. Curtis’s Bot. Mag. 11: 59-65
Graham, R. (1840). Heterotropha asaroides. Curtis’s Bot. Mag. 66: t.3746.
Image: Kindly donated by Takato Natsui: http://cyberlaw.la.coocan.jp/index.html
The Plant List (2010). Asarum asaroides. http://www.theplantlist.org/tpl/record/kew-2654258 (accessed 4 May 2011).
Wilford, R. (2010). Alpines from Mountain to Garden. Royal Botanic Gardens, Kew.
Kew Science Editors: Malin Rivers and Richard Wilford
While every effort has been taken to ensure that the information contained in these pages is reliable and complete, the notes on hazards, edibility and suchlike included here are recorded information and do not constitute recommendations. No responsibility will be taken for readers’ own actions. Full website terms and conditions.
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Nymphaea thermarum
Nymphaea thermarum is the smallest waterlily in the world, and the only Nymphaea to grow in damp mud rather than water.
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