Epimedium
Encyclopedia
Epimedium, also known as Rowdy Lamb Herb, Barrenwort, Bishop's Hat, Fairy Wings, Horny Goat Weed, or Yin Yang Huo , is a genus
of about 60 or more species of herbaceous
flowering plant
s in the family Berberidaceae
. The large majority are endemic to southern China, with further outposts in Europe
, and central, southern and eastern Asia
.
Epimedium species are hardy perennials
. The majority have four-petaled "spider-like" flowers in spring. Many are believed to be aphrodisiac
s, particularly horny goat weed.
, extending the boundaries of the genus in cultivation. Few genera of plants have seen such a dramatic increase in new species, primarily thanks to the work of Mikinori Ogisu of Japan and Darrell Probst of Massachusetts. The majority of the Chinese species have not been fully tested for hardiness
or indeed for any other aspect of their culture. The initial assumption that the plants would only thrive where their native conditions could be closely replicated have proven to be overly cautious, as most varieties are proving extraordinarily amenable to general garden and container cultivation.
Hybrids include Epimedium versicolor (see illustration).
in early spring, Epimedium are best divided
in late August, with the aim of promoting rapid re-growth of root
s and shoots before the onset of winter. Several breeders
(in particular Darrell Probst, Tim Branney & Robin White) have also undertaken their own hybridization programmes with the genus Epimedium. Various new nursery
selections are gradually appearing in the nursery trade, the best of which are extending the colour and shape range of the flowers available to the gardener.
Given suitable conditions most Epimedium will form beautiful ground cover plants, often with magnificent new leaves tinted in bronze, copper and reds combining with a huge variety of flower colours and forms in spring. Handsome and dense-growing foliage remains present for much of the year, with the leaves often turning purple, crimson and scarlet in autumn in some forms, and remaining evergreen in others. With all varieties, however, the foliage is best cut off at ground level shortly before new leaves emerge, so as to fully reveal their beauty of form and colour. Ideally, a mulch should then be applied to protect the new growth from frosts.
From the gardeners point of view Epimedium flowers comprise two main parts, the inner sepals, which are petal-like and four in number (the four outer sepals are small, insignificant, and rapidly shed as the flowers open) and the petals, which are held within the sepals. In some species these petals have developed long spurs and in such plants they greatly exceed the size of the surrounding sepals, producing a flower shaped like an inverted crown, and also giving rise to one of the common names for Epimedium- bishops hat. In other species, however, (such as E. perraldianum) the petals are reduced to tiny spurs, and it is the greatly enlarged and highly coloured sepals that have expanded to catch the attention of the wandering insect.
qualities. According to legend, this property was discovered by a Chinese
goat
herder who noticed sexual activity in his flock after they ate the weed. It is sold as a health supplement; usually in raw herb, tablet, or capsule form and sometimes blended with other supplements. The over-exploitation of wild populations of Epimedium for use in traditional Chinese medicine is having potentially serious consequences for the long-term survival of several species, none of which is widely cultivated for medicinal purposes.
The "active ingredient" in Epimedium is icariin
, which can be found in standardized extracts from 5% up to 60% potent. Strengths above that are usually reserved for lab use.
Icariin is purported to work by increasing levels of nitric oxide
, which relax smooth muscle
. It has been demonstrated to relax rabbit penile tissue by nitric oxide and PDE-5 activity. Other research has demonstrated that injections of Epimedium extract directly into the penis of the rat results in an increase in penile blood pressure.
Like sildenafil
(Viagra), icariin, the active compound in Epimedium, inhibits the activity of PDE-5. In vitro assays have demonstrated that icariin weakly inhibits PDE-5 with an IC50
of around 1 μM, while sildenafil has an IC50
of about 6.6 nM (.0066 μM) and vardenafil
(Levitra) has an IC50
of about 0.7 nM (.0007 μM). Measured differently, the EC50
of icariin is approximately 4.62 μM, while sildenafil's is .42 μM. With the weak potency of Epimedium, and its unknown oral bioavailability, the amount of Epidemium extract necessary to have any effect is unclear from the literature.
A recently published Italian study modified icariin structurally and investigated a number of derivatives
. Inhibitory concentrations for PDE-5 close to sildenafil could be reached. Moreover, the most potent PDE-5 inhibitor of this series was also found to be a less potent inhibitor of phosphodiesterase-6 (PDE-6) and cyclic adenosine monophosphate-phosphodiesterase (cAMP-PDE), thus showing it to have more specificity for PDE-5 than sildenafil.
Epimedium has been shown to up-regulate genes associated with nitric oxide production and changes in adenosine/guanine monophosphate balance in ways that other PDE5 inhibitors do not. Epimedium may have potential to help sexual dysfunction and osteoporosis
.
also stimulates osteoblast
activity in bone tissue, leading to the development and marketing of medicinal products based on Epimedium extracts for treatment of osteoporosis
.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of about 60 or more species of herbaceous
Herbaceous
A herbaceous plant is a plant that has leaves and stems that die down at the end of the growing season to the soil level. They have no persistent woody stem above ground...
flowering plant
Flowering plant
The flowering plants , also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants. Angiosperms are seed-producing plants like the gymnosperms and can be distinguished from the gymnosperms by a series of synapomorphies...
s in the family Berberidaceae
Berberidaceae
Berberidaceae are a family of 15 genera flowering plants commonly called the barberry family. This family is in the order Ranunculales. The family contains about 570 species, of which the majority are in Berberis...
. The large majority are endemic to southern China, with further outposts in Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, and central, southern and eastern Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
.
Epimedium species are hardy perennials
Perennial plant
A perennial plant or simply perennial is a plant that lives for more than two years. The term is often used to differentiate a plant from shorter lived annuals and biennials. The term is sometimes misused by commercial gardeners or horticulturalists to describe only herbaceous perennials...
. The majority have four-petaled "spider-like" flowers in spring. Many are believed to be aphrodisiac
Aphrodisiac
An aphrodisiac is a substance that increases sexual desire. The name comes from Aphrodite, the Greek goddess of sexuality and love. Throughout history, many foods, drinks, and behaviors have had a reputation for making sex more attainable and/or pleasurable...
s, particularly horny goat weed.
Cultivation
Some varieties and hybrids have been in Western cultivation for the last 100 to 150 years. There are now a wide array of new Chinese species being cultivated in the west, many of which have only recently been discovered, and a number of which have yet to be named. There are also many older Japanese hybrids and formsForm (botany)
In botanical nomenclature, a form is one of the "secondary" taxonomic ranks, below that of variety, which in turn is below that of species; it is an infraspecific taxon...
, extending the boundaries of the genus in cultivation. Few genera of plants have seen such a dramatic increase in new species, primarily thanks to the work of Mikinori Ogisu of Japan and Darrell Probst of Massachusetts. The majority of the Chinese species have not been fully tested for hardiness
Hardiness (plants)
Hardiness of plants describe their ability to survive adverse growing conditions. It is usually limited to discussions of climatic adversity. Thus a plant's ability to tolerate cold, heat, drought, flooding, or wind are typically considered measurements of hardiness. Hardiness of plants is defined...
or indeed for any other aspect of their culture. The initial assumption that the plants would only thrive where their native conditions could be closely replicated have proven to be overly cautious, as most varieties are proving extraordinarily amenable to general garden and container cultivation.
Hybrids include Epimedium versicolor (see illustration).
Propagation
While they can be successfully propagatedPlant propagation
Plant propagation is the process of creating new plants from a variety of sources: seeds, cuttings, bulbs and other plant parts. Plant propagation can also refer to the artificial or natural dispersal of plants.-Sexual propagation :...
in early spring, Epimedium are best divided
Division (horticulture)
Division, in horticulture and gardening, is a method of asexual plant propagation, where the plant is broken up into two or more parts...
in late August, with the aim of promoting rapid re-growth of root
Root
In vascular plants, the root is the organ of a plant that typically lies below the surface of the soil. This is not always the case, however, since a root can also be aerial or aerating . Furthermore, a stem normally occurring below ground is not exceptional either...
s and shoots before the onset of winter. Several breeders
Plant breeding
Plant breeding is the art and science of changing the genetics of plants in order to produce desired characteristics. Plant breeding can be accomplished through many different techniques ranging from simply selecting plants with desirable characteristics for propagation, to more complex molecular...
(in particular Darrell Probst, Tim Branney & Robin White) have also undertaken their own hybridization programmes with the genus Epimedium. Various new nursery
Nursery (horticulture)
A nursery is a place where plants are propagated and grown to usable size. They include retail nurseries which sell to the general public, wholesale nurseries which sell only to businesses such as other nurseries and to commercial gardeners, and private nurseries which supply the needs of...
selections are gradually appearing in the nursery trade, the best of which are extending the colour and shape range of the flowers available to the gardener.
Garden uses
Hugely popular as garden plants for centuries in Japan, Epimedium are only just beginning to garner attention in the West. While they vary somewhat in their respective hardiness, all are essentially dwellers of the forest floor, and, as such, all require fundamentally similar conditions of moist, free draining, humus rich soil and cool shade, with some shelter for the newly emerging leaves. Some of the more robust varieties are often recommended as plants for dry shade, and whilst their tough foliage and stout rhizomes can allow them to grow successfully in such conditions, (and in more open, exposed positions too, in some instances) they will certainly not give their best. Furthermore, dryness and exposure will pretty much guarantee the early death of many of the newer and more delicate species.Given suitable conditions most Epimedium will form beautiful ground cover plants, often with magnificent new leaves tinted in bronze, copper and reds combining with a huge variety of flower colours and forms in spring. Handsome and dense-growing foliage remains present for much of the year, with the leaves often turning purple, crimson and scarlet in autumn in some forms, and remaining evergreen in others. With all varieties, however, the foliage is best cut off at ground level shortly before new leaves emerge, so as to fully reveal their beauty of form and colour. Ideally, a mulch should then be applied to protect the new growth from frosts.
Flower forms
Aphrodisiac
Many species of Epimedium are alleged to have aphrodisiacAphrodisiac
An aphrodisiac is a substance that increases sexual desire. The name comes from Aphrodite, the Greek goddess of sexuality and love. Throughout history, many foods, drinks, and behaviors have had a reputation for making sex more attainable and/or pleasurable...
qualities. According to legend, this property was discovered by a Chinese
Zhonghua minzu
Zhonghua minzu , usually translated as Chinese ethnic groups or Chinese nationality, refers to the modern notion of a Chinese nationality transcending ethnic divisions, with a central identity for China as a whole...
goat
Goat
The domestic goat is a subspecies of goat domesticated from the wild goat of southwest Asia and Eastern Europe. The goat is a member of the Bovidae family and is closely related to the sheep as both are in the goat-antelope subfamily Caprinae. There are over three hundred distinct breeds of...
herder who noticed sexual activity in his flock after they ate the weed. It is sold as a health supplement; usually in raw herb, tablet, or capsule form and sometimes blended with other supplements. The over-exploitation of wild populations of Epimedium for use in traditional Chinese medicine is having potentially serious consequences for the long-term survival of several species, none of which is widely cultivated for medicinal purposes.
The "active ingredient" in Epimedium is icariin
Icariin
Icariin is a flavonol, a type of flavonoid. It is the prenyl acetylation of kaempferide 3,7-O-diglucoside. The compound is derived from several species of plants in the Epimedium family, which are commonly known as Horny Goat Weed or Yin Yang Huo...
, which can be found in standardized extracts from 5% up to 60% potent. Strengths above that are usually reserved for lab use.
Icariin is purported to work by increasing levels of nitric oxide
Nitric oxide
Nitric oxide, also known as nitrogen monoxide, is a diatomic molecule with chemical formula NO. It is a free radical and is an important intermediate in the chemical industry...
, which relax smooth muscle
Smooth muscle
Smooth muscle is an involuntary non-striated muscle. It is divided into two sub-groups; the single-unit and multiunit smooth muscle. Within single-unit smooth muscle tissues, the autonomic nervous system innervates a single cell within a sheet or bundle and the action potential is propagated by...
. It has been demonstrated to relax rabbit penile tissue by nitric oxide and PDE-5 activity. Other research has demonstrated that injections of Epimedium extract directly into the penis of the rat results in an increase in penile blood pressure.
Like sildenafil
Sildenafil
Sildenafil citrate, sold as Viagra, Revatio and under various other trade names, is a drug used to treat erectile dysfunction and pulmonary arterial hypertension . It was originally developed by British scientists and then brought to market by the US-based pharmaceutical company Pfizer...
(Viagra), icariin, the active compound in Epimedium, inhibits the activity of PDE-5. In vitro assays have demonstrated that icariin weakly inhibits PDE-5 with an IC50
IC50
The half maximal inhibitory concentration is a measure of the effectiveness of a compound in inhibiting biological or biochemical function. This quantitative measure indicates how much of a particular drug or other substance is needed to inhibit a given biological process by half...
of around 1 μM, while sildenafil has an IC50
IC50
The half maximal inhibitory concentration is a measure of the effectiveness of a compound in inhibiting biological or biochemical function. This quantitative measure indicates how much of a particular drug or other substance is needed to inhibit a given biological process by half...
of about 6.6 nM (.0066 μM) and vardenafil
Vardenafil
Vardenafil is a PDE5 inhibitor used for treating erectile dysfunction that is sold under the trade names Levitra and Staxyn.-History:...
(Levitra) has an IC50
IC50
The half maximal inhibitory concentration is a measure of the effectiveness of a compound in inhibiting biological or biochemical function. This quantitative measure indicates how much of a particular drug or other substance is needed to inhibit a given biological process by half...
of about 0.7 nM (.0007 μM). Measured differently, the EC50
EC50
The term half maximal effective concentration refers to the concentration of a drug, antibody or toxicant which induces a response halfway between the baseline and maximum after some specified exposure time...
of icariin is approximately 4.62 μM, while sildenafil's is .42 μM. With the weak potency of Epimedium, and its unknown oral bioavailability, the amount of Epidemium extract necessary to have any effect is unclear from the literature.
A recently published Italian study modified icariin structurally and investigated a number of derivatives
Derivative (chemistry)
In chemistry, a derivative is a compound that is derived from a similar compound by some chemical or physical process. In the past it was also used to mean a compound that can be imagined to arise from another compound, if one atom is replaced with another atom or group of atoms, but modern...
. Inhibitory concentrations for PDE-5 close to sildenafil could be reached. Moreover, the most potent PDE-5 inhibitor of this series was also found to be a less potent inhibitor of phosphodiesterase-6 (PDE-6) and cyclic adenosine monophosphate-phosphodiesterase (cAMP-PDE), thus showing it to have more specificity for PDE-5 than sildenafil.
Epimedium has been shown to up-regulate genes associated with nitric oxide production and changes in adenosine/guanine monophosphate balance in ways that other PDE5 inhibitors do not. Epimedium may have potential to help sexual dysfunction and osteoporosis
Osteoporosis
Osteoporosis is a disease of bones that leads to an increased risk of fracture. In osteoporosis the bone mineral density is reduced, bone microarchitecture is deteriorating, and the amount and variety of proteins in bone is altered...
.
Osteoporosis
Animal studies indicate that IcariinIcariin
Icariin is a flavonol, a type of flavonoid. It is the prenyl acetylation of kaempferide 3,7-O-diglucoside. The compound is derived from several species of plants in the Epimedium family, which are commonly known as Horny Goat Weed or Yin Yang Huo...
also stimulates osteoblast
Osteoblast
Osteoblasts are mononucleate cells that are responsible for bone formation; in essence, osteoblasts are specialized fibroblasts that in addition to fibroblastic products, express bone sialoprotein and osteocalcin.Osteoblasts produce a matrix of osteoid, which is composed mainly of Type I collagen...
activity in bone tissue, leading to the development and marketing of medicinal products based on Epimedium extracts for treatment of osteoporosis
Osteoporosis
Osteoporosis is a disease of bones that leads to an increased risk of fracture. In osteoporosis the bone mineral density is reduced, bone microarchitecture is deteriorating, and the amount and variety of proteins in bone is altered...
.
Chemistry
Epimedium wushanense,contains a number of flavanoids. A total of 37 compounds were characterized from the underground and aerial parts of the plant. Among them, 28 compounds were prenylated flavonoids. The predominant flavonoid, epimedin C, ranged from 1.4 to 5.1% in aerial parts and 1.0 to 2.8% in underground parts.Literature
- Epimedium Care and Culture(Heronswood Nursery)
- William T. StearnWilliam T. StearnWilliam Thomas Stearn CBE was a British botanist known for his expertise on the history of botany and in the classical languages. His work is widely read, with his etymological dictionary of Latin names of garden plants likely the best-known of the works appearing under his own name...
, The Genus Epimedium, revised edition 2002, ISBN 0-88192-543-8 - An Overview of Epimedium, in The Plantsman, March 2010, by Tony AventTony AventTony Avent is an American Horticulturist and Plantsman. He is the owner of Plant Delights Nursery and the founder of the Juniper Level Botanic Garden in Raleigh, North Carolina. In addition, he is a well-known plant explorer, author and public speaker....
of Plant Delights NurseryPlant Delights NurseryPlant Delights Nursery is a mail order plant nursery based in Raleigh, North Carolina specializing in herbaceous perennials. Plant Delights was founded in 1988 by the plantsman Tony Avent and his wife Michelle Avent. The nursery currently has a 2.5 acre production facility. Proceeds from the...