''Asarum'' is a genus of plants in the birthwort family Aristolochiaceae, commonly known as wild ginger. ''Asarum'' is from Greek ἄσαρον, a name for '' Asarum europaeum''.

Description

''Asarum'' is a genus of low-growing herbs distributed across the temperate zones of the Northern Hemisphere, with most species in East Asia (China, Japan, and Vietnam) and North America, and one species in Europe. Biogeographically, ''Asarum'' originated in Asia. They have characteristic kidney-shaped leaves, growing from creeping rhizomes, and bear small, axillary, brown or reddish flowers. The plant is called wild ginger because the rhizomes and leaves taste and smell similar to

ginger Ginger (''Zingiber officinale'') is a flowering plant whose rhizome, ginger root or ginger, is widely used as a spice and a folk medicine. It is an herbaceous perennial that grows annual pseudostems (false stems made of the rolled bases of l ...

root, but the two are not particularly related. The FDA warns against consuming ''Asarum'', as it is nephrotoxic and contains the potent

carcinogen A carcinogen () is any agent that promotes the development of cancer. Carcinogens can include synthetic chemicals, naturally occurring substances, physical agents such as ionizing and non-ionizing radiation, and biologic agents such as viruse ...

aristolochic acid Aristolochic acids () are a family of carcinogenic, mutagenic, and nephrotoxic phytochemicals commonly found in the flowering plant family Aristolochiaceae (birthworts). Aristolochic acid (AA) I is the most abundant one. The family Aristolochiace ...

. The birthwort family also contains the genus '' Aristolochia'', known for carcinogens. Wild ginger favors moist, shaded sites with

humus In classical soil science, humus is the dark organic matter in soil that is formed by the decomposition of plant and animal matter. It is a kind of soil organic matter. It is rich in nutrients and retains moisture in the soil. Humus is the Lati ...

-rich soil. The deciduous, heart-shaped

leaves A leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, ...

are opposite, and borne from the rhizome which lies just under the soil surface. Two leaves emerge each year from the growing tip. The curious jug-shaped

flower Flowers, also known as blooms and blossoms, are the reproductive structures of flowering plants ( angiosperms). Typically, they are structured in four circular levels, called whorls, around the end of a stalk. These whorls include: calyx, m ...

s, which give the plant an alternate name, little jug, are borne singly in spring between the leaf bases. Wild ginger can easily be grown in a shade garden, and makes an attractive groundcover. Asarum europaeum flower 050403

Taxonomy

Traditionally, the genus ''Asarum'' was considered as a single genus with about 85 species. However, a trend exists among some botanists to segregate the genus into separate genera, based on considerations of chromosome number and floral morphology: * ''Asarum'' ''sensu stricto'' (about 17 species), distributed in Asia (mainly China), North America, and Europe * '' Heterotropa'' (about 50 species), distributed in Asia * '' Asiasarum'' (three or four species), distributed in Asia * '' Geotaenium'' (three or four species), distributed in Asia * '' Hexastylis'' (ten species), distributed in North America Study of the internal transcribed spacer region (ITS) of nuclear

ribosomal DNA The ribosomal DNA (rDNA) consists of a group of ribosomal RNA encoding genes and related regulatory elements, and is widespread in similar configuration in all domains of life. The ribosomal DNA encodes the non-coding ribosomal RNA, integral struc ...

, combined with morphological data, has yielded a better-resolved phylogenetic hypothesis, supporting a recognition of two subgenera, ''Asarum'' and ''Heterotropa'' each containing two sections, rather than the segregated genera above. *''Asarum'' ''sensu stricto'' (''s.s.'') : the North American species are

monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...

and are derived from within the

paraphyletic Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...

Asian species group. * ''Geotaenium'' is a sister to ''Asarum'' ''s.s.'', showing its close relationship to ''Asarum'' ''s.s.''. * ''Asiasarum'' is a sister to the ''Hexastylis'' + ''Heterotropa'' clade, showing several synapomorphies with this clade. * ''Hexastylis'': this genus has been recognized solely on the study by H.L. Blomquist. However, the above-mentioned DNA study provided indications that ''Hexastylis'' is not monophyletic and that some species of ''Hexastylis'' are more closely related to Asiatic species of ''Heterotropa'' than they are to other species of ''Hexastylis''. The recognition of ''Hexastylis'' has likely persisted due to regional botanists' contrasting the morphology of that section with the regionally co-occurring ''Asarum canadense'', which is the sole species of Asarum subgenus Asarum in the southeastern United States. However, the morphological character states used to support the recognition of section Hexastylis at the generic level are plesiomorphic. For example, Blomquist provides an enumeration of character states supporting ''Hexastylis'', all of are plesiomorphic with respect to one or another ''Asarum'' lineage. The presence of persistent, variegated leaves is often invoked by amateur botanists as a characteristic unique to section Hexastylis amongst North American ''Asarum'' species, however '' Asarum marmoratum'', an ''Asarum'' Subgenus Asarum species found in the western United States also has persistent and variegated leaves
see Calflora page for detailed photographs
* ''Heterotropa'': this is a complex monophyletic group, well nested within the ''Asiasarum'' + ''Hexastylis'' + ''Heterotropa'' clade.

Species

Uses

The FDA warns against consuming ''Asarum'', as it is nephrotoxic and contains the potent

. Before this was known, sources said that wild ginger can be cooked in the same fashion as ginger root, and can also be candied or used to make medicine.

References

External links

* *
List of ''Asarum'' speciesThe International Agency for Research on Cancer
{{Taxonbar, from=Q157718 Piperales genera Herbs