''Kerria japonica'', commonly known as Japanese kerria or Japanese rose, is a
deciduous
In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals, ...
family
Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...
( Rosaceae), native to China, Japan and Korea. It is the only species in the genus Kerria. In the wild, it grows in thickets on mountain slopes. Japanese kerria has been used for medicine and is also planted in gardens. A double-flowered
cultivar
A cultivar is a type of cultivated plant that people have selected for desired traits and when propagated retain those traits. Methods used to propagate cultivars include: division, root and stem cuttings, offsets, grafting, tissue culture ...
, ''K. japonica'' 'Pleniflora', is commonly called bachelor's buttons.
Name
The genus name ''Kerria'' is also a common name for the species (Kerria). It is named after Scottish gardener William Kerr, who introduced the Japanese kerria
cultivar
A cultivar is a type of cultivated plant that people have selected for desired traits and when propagated retain those traits. Methods used to propagate cultivars include: division, root and stem cuttings, offsets, grafting, tissue culture ...
'Pleniflora'.
It is sometimes known by the Japanese ''yamabuki'' (, Chinese pronunciation of characters ''shānchuī'') (= "mountain
butterbur
''Petasites'' is a genus of flowering plants in the sunflower family, Asteraceae, that are commonly referred to as butterburs and coltsfoots.
flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ...
s are golden yellow, with five
petals
Petals are modified leaves that surround the reproductive parts of flowers. They are often brightly colored or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''corolla''. Petals are usually ...
, and evenly-spaced along branches of new green growth. The
fruit
In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering.
Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in particu ...
is a dry single-
seed
A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiospe ...
Kerria is valued in gardens for its golden yellow flowers, which appear in the spring. It is best grown with some shade from full sunlight to avoid blanching the flowers, and needs to be pruned after flowering to maintain health and vigour. Two cultivars have gained the
Royal Horticultural Society
The Royal Horticultural Society (RHS), founded in 1804 as the Horticultural Society of London, is the UK's leading gardening charity.
The RHS promotes horticulture through its five gardens at Wisley (Surrey), Hyde Hall (Essex), Harlow Carr (Nor ...
's Award of Garden Merit, ''K. japonica'' 'Golden guinea' and the double-flowered ''K. japonica'' 'Pleniflora', commonly known as bachelor's buttons.
Pests and diseases
Since 2014 the UK's Royal Horticultural Society has been receiving reports from gardeners and horticulturalists of damage to plants of the shrub ''Kerria japonica''. Symptoms include multiple red spots on leaves, and
lesion
A lesion is any damage or abnormal change in the tissue of an organism, usually caused by disease or trauma. ''Lesion'' is derived from the Latin "injury". Lesions may occur in plants as well as animals.
Types
There is no designated classif ...
s on the stems, resulting in
defoliation
A defoliant is any herbicidal chemical sprayed or dusted on plants to cause their leaves to fall off. Defoliants are widely used for the selective removal of weeds in managing croplands and lawns. Worldwide use of defoliants, along with the ...
and eventual death. It has been determined that this infection is caused by the fungus '' Blumeriella kerriae'', which is specific to the kerria. This highly contagious disease, known in English as kerria twig and leaf blight, was known in the U.S. but has not previously been observed on British plants. It is regarded as a serious threat to the cultivated kerria plants, which are popular garden shrubs.
Medicinal use
The plant has
anti-inflammatory
Anti-inflammatory is the property of a substance or treatment that reduces inflammation or swelling. Anti-inflammatory drugs, also called anti-inflammatories, make up about half of analgesics. These drugs remedy pain by reducing inflammation as o ...
properties and a
decoction
Decoction is a method of extraction by boiling herbal or plant material (which may include stems, roots, bark and rhizomes) to dissolve the chemicals of the material. It is the most common preparation method in various herbal-medicine systems. Dec ...
of the flowering shoots with
honey
Honey is a sweet and viscous substance made by several bees, the best-known of which are honey bees. Honey is made and stored to nourish bee colonies. Bees produce honey by gathering and then refining the sugary secretions of plants (primar ...
has been used in China in the treatment of
cough
A cough is a sudden expulsion of air through the large breathing passages that can help clear them of fluids, irritants, foreign particles and microbes. As a protective reflex, coughing can be repetitive with the cough reflex following three ph ...
s and gynecological disorders.Duke, A. and Ayensu, Edward S., ''Medicinal Plants of China'', pub. Reference Publications, inc. 1985 vol. II p.546.
Chemistry
The leaves and roots contain 0.002% Hydrogen cyanide, while the tender shoots are a rich source of
Vitamin C
Vitamin C (also known as ascorbic acid and ascorbate) is a water-soluble vitamin found in citrus and other fruits and vegetables, also sold as a dietary supplement and as a topical 'serum' ingredient to treat melasma (dark pigment spots) ...
(200 mg/100g) and the seeds contain 44.9%
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...
and 45.3%
fat
In nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such compounds, most commonly those that occur in living beings or in food.
The term often refers specifically to triglycerides (triple est ...
. The flower petals contain the
O-methylated flavonoid The O-methylated flavonoids or methoxyflavonoids are flavonoids with methylations on hydroxyl groups ( methoxy bonds). O-methylation has an effect on the solubility of flavonoids.
Enzymes
O-methylated flavonoids formation implies the presence of sp ...
pectolinarin, (5,7-dihydroxy-4,6-dimethoxyflavone-7-rutinoside), a cytotoxic compound known also as Neolinarin and found also in
Linaria
''Linaria'' is a genus of almost 200 species of flowering plants, one of several related groups commonly called toadflax. They are annuals and herbaceous perennials, and the largest genus in the Antirrhineae tribe of the plantain family Plan ...
Duranta
''Duranta'' is a genus of flowering plants in the verbena family, Verbenaceae. It contains 17 species of shrubs and small trees that are native from southern Florida to Mexico and South America. They are commonly cultivated as hedges and ornament ...
species ''D. plumieri''.Blunt, John W. and Munro, Murray H. G. ''Dictionary of Marine Natural Products'' pub. Chapman & Hall/CRC Taylor and Francis Group 2007 page 614.
In culture
''Kerria japonica'' is mentioned frequently in the '' Man'yōshū'', the oldest extant collection of Japanese poetry from the AD first millennium. In addition, the Japanese call the golden yellow color (variously #FFA400, #FFBF00, #F8B500) between orange and yellow ''yamabuki'' color ( ''yamabuki-iro''), from the name of the plant.
Qing Dynasty
The Qing dynasty ( ), officially the Great Qing,, was a Manchu-led imperial dynasty of China and the last orthodox dynasty in Chinese history. It emerged from the Later Jin dynasty founded by the Jianzhou Jurchens, a Tungusic-spea ...
poet Chen Hao () celebrated the beauty of ''Kerria japonica'' in his agricultural treatise the ().