Comfrey
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224857004
2008-07-10T18:49:26Z
JoJan
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Reverted 1 edit by [[Special:Contributions/210.4.113.178|210.4.113.178]]. ([[WP:TW|TW]])
{{Taxobox
| name = ''Symphytum''
| image = Russian comfrey 800.jpg
| image_width = 250px
| image_caption = Russian comfrey (''Symphytum x uplandicum'')
| regnum = [[Plantae]]
| divisio = [[Flowering plant|Magnoliophyta]]
| classis = [[Magnoliopsida]]
| ordo = [[Lamiales]]
| familia = [[Boraginaceae]]
| genus = '''''Symphytum'''''
| subdivision_ranks = Species
| subdivision =
*''[[Symphytum asperum]]'' Lepechin
*''[[Symphytum officinale]]'' L.
*''[[Symphytum tuberosum]]'' L.
*''Symphytum x uplandicum'' Nyman
}}
''For the place, see [[Comfrey, Minnesota]]''
'''Comfrey''' (also '''comphrey''') is an important [[herb]] in [[organic gardening]], having many medicinal and fertilizer<ref> [http://www.the-organic-gardener.com/Comfrey.html Comfrey as a fertilizer] </ref> uses.
==Description==
'''Comfrey''' (''Symphytum officinale'' L.) is a perennial herb of the [[family (biology)|family]] [[Boraginaceae]] with a black, turnip-like root and large, hairy broad leaves that bears small bell-shaped white, cream, purple or pink flowers. It is native to [[Europe]], growing in damp, grassy places, and is widespread throughout the British Isles on river banks and ditches. Comfrey has long been recognised by both organic gardeners and herbalists for its great usefulness and versatility; of particular interest is the "Bocking 14" cultivar of Russian Comfrey (''Symphytum x uplandicum''). This strain was developed during the 1950s by [[Lawrence D Hills]], the founder of the [[Henry Doubleday Research Association]] (the [[organic gardening]] organisation itself named after the [[Quaker]] pioneer who first introduced Russian Comfrey into Britain in the 1910s) following trials at [[Bocking]], near [[Braintree, Essex|Braintree]], the original home of the organisation.
Other species include:
* ''Symphytum asperum'', Prickly Comfrey, Rough Comfrey (synonym: ''S. asperrimum'')
* ''Symphytum bulbosum'', Bulbous Comfrey
* ''Symphytum caucasicum'', Caucasian Comfrey
* ''Symphytum grandiflorum'', Creeping Comfrey (synonym: ''S. ibericum'')
* ''Symphytum orientale'', White Comfrey
* ''Symphytum tauricum'', Crimean Comfrey
* ''Symphytum tuberosum'', Tuberous Comfrey
* ''Symphytum x uplandicum'', Russian Comfrey, Healing Herb, Blackwort, Bruisewort, Wallwort, Gum Plant. (''S. asperum x officinale'', synonym: ''S. peregrinum'')
== Propagation ==
Bocking 14 is sterile, and therefore will not set seed (one of its advantages over other cultivars as it will not spread out of control), thus is propagated from [[root cutting]]s. The gardener can produce their own 'offsets' from mature, strongly growing plants by driving a spade horizontally through the leaf clumps about 3 [[inch]]es below the soil surface. This removes the crown which can then be split into pieces. The original plant will quickly recover, and each piece can be replanted with the growing points just below the soil surface, and will quickly grow into new plants. When choosing plants to divide ensure that they are strong healthy specimens with no signs of [[Rust (fungus)|rust]] or [[mildew]]. When dividing comfrey plants take care not to spread root fragments around, or dispose of on the [[compost]] heap as each can re-root, and comfrey can be a very difficult plant to get rid of. Offsets can also be purchased by mail order from specialist nurseries in order to initially build up a stock of plants.
== Cultivation ==
The comfrey bed should be well prepared by weeding thoroughly, and dressing with [[manure]] if available. Offsets should be planted 2-3 feet apart with the growing points just below the surface, whilst root segments should be buried about 2 inches deep. Keep the bed well watered until the young plants are established. Comfrey should not be harvested in its first season as it needs to become established. Any flowering stems should be removed as these will weaken the plants in its first year. Comfrey should also be regularly watered until well established.
Comfrey is a fast growing plant, producing huge amounts of leaf during the growing season, hence is very [[nitrogen]] hungry. Although it will continue to grow no matter what, it will benefit from the addition of animal manure applied as a mulch, and can also be mulched with other nitrogen rich materials such as lawn mowings, and is one of the few plants that will tolerate the application of fresh [[urine]] diluted 50:50 with water, although this should not be regularly added as it may increase salt levels in the soil and have adverse effects on [[soil life]] such as [[worm]]s. Mature comfrey plants can be harvested up to four or five times a year. They are ready for cutting when about 2 feet high, and, depending on seasonal conditions, this is usually in mid-Spring. Comfrey will rapidly regrow, and will be ready for further cutting about 5 weeks later. It is said that the best time to cut comfrey is shortly before flowering, for this is when it is at its most potent in terms of the nutrients that it offers. Comfrey can continue growing into mid-Autumn, but it is not advisable to continue taking cuttings after early Autumn in order to allow the plants to build up winter reserves. As the leaves die back and break down in winter, nutrients and minerals are transported back to the roots for use the following spring.
Comfrey should be harvested by using either [[shears]] a [[sickle]] or a [[scythe]] to cut the plant about 2 inches above the ground, taking care handling it because the leaves and stems are covered in hairs that can irritate the skin. It is advisable to wear gloves when handling comfrey. Despite being sterile, Bocking 14 Russian Comfrey will steadily increase in size. It is therefore advisable to split it up every few years (and at the same time propagate more plants that can be shared with fellow gardeners!). It is however difficult to remove comfrey once established as it is very deep rooting, and any fragments left in the soil will regrow. Rotovation can be successful, but may take several seasons. The best way to eradicate comfrey is to very carefully dig it out, removing as much of the root as possible. This is best done in hot, dry summer weather, wherein the dry conditions will help to kill off any remaining root stumps. Comfrey is generally trouble free once established, although weaker or stressed plants can suffer from comfrey rust or mildew. Both are [[fungus|fungal]] diseases, although they rarely seriously reduce plant growth and thus do not generally require control. However infected plants should not be used for propagation purposes.
== Medicinal uses ==
Dorothy Hall writes that 'Russian comfrey and garlic could together, according to natural health usage, almost halve the present ills of western civilisation' <ref>Hall, D, The Book Of Herbs, Pan 1976</ref>. An extravagant claim perhaps, but comfrey did indeed have a wealth of medicinal uses in bygone days. Contemporary herbalists view comfrey as an ambivalent and controversial herb that may offer therapeutic benefits but at the potential risk of liver toxicity.
One of its country names for comfrey was 'knitbone', a reminder of its traditional use in healing. Modern science confirms that comfrey can influence the course of bone ailments. <ref>PMID: 16510384 Adv Ther. 2005 Nov-Dec;22(6):681-92 Topical symphytum herb concentrate cream against myalgia: a randomized controlled double-blind clinical study.</ref>
<ref>PMID: 15638067 Phytomedicine. 2004 Sep;11(6):470-7. Efficacy and tolerance of a comfrey root extract (Extr. Rad. Symphyti) in the treatment of ankle distorsions: results of a multicenter, randomized, placebo-controlled, double-blind study. </ref>
<ref>PMID: 14518351 Fortschr Med Orig. 2002;120(1):1-9. Therapeutic characteristance and tolerance of topical comfrey preparations. Results of an observational study of patients </ref>
<ref>PMID: 17169543 Phytomedicine. 2007 Jan;14(1):2-10. Epub 2006 Dec 13. Efficacy of a comfrey root (Symphyti offic. radix) extract ointment in the treatment of patients with painful osteoarthritis of the knee: results of a double-blind, randomised, bicenter, placebo-controlled trial. </ref>
The herb contains [[allantoin]], a cell proliferant that speeds up the natural replacement of body cells. Comfrey was used to treat a wide variety of ailments ranging from bronchial problems, broken bones, sprains, arthritis, gastric and varicose ulcers, severe burns, acne and other skin conditions. It was reputed to have bone and teeth building properties in children, and have value in treating 'many female disorders'. In past times comfrey baths were popular to repair the hymen and thus 'restore virginity'. Constituents of comfrey also include [[mucilage]], [[steroidal saponin]]s, [[tannin]]s, [[pyrrolizidine]] alkaloids, [[inulin]], [[vitamin B12]] and [[protein]]s.
[[Image:Russian comfrey close 800.jpg|thumb|250px|right|The flowers of Russian comfrey]]
Internal usage of comfrey should be avoided because it contains [[Hepatotoxicity|hepatotoxic]] [[pyrrolizidine]] alkaloids (PAs) (Note, there are also non-hepatotoxic pyrrolizidine alkaloids.). Use of comfrey can, because of these PAs, lead to [[veno-occlusive disease]] (VOD). VOD can in turn lead to [[liver]] failure, and comfrey, taken in extreme amounts, has been implicated in at least one death. <ref>Yeong M.L., et al.(1990), "Hepatic veno-occlusive disease associated with comfrey ingestion." Journal of Gastroenterology and Hepatology, 5(2): p. 211-4.</ref> In 2001, the [[United States]] [[Food and Drug Administration]] issued a warning against internal usage of herbal products containing comfrey. <ref>{{cite web |url=http://vm.cfsan.fda.gov/~dms/dspltr06.html |title=FDA/CFSAN - FDA Advises Dietary Supplement Manufacturers to Remove Comfrey Products From the Market |accessdate=2007-06-01 |format= |work=}}</ref> There are ways to remove the pyrrolizidine alkaloids from comfrey, and some herbal product manufacturers have begun doing so (although the products will still be labelled "for external use only.")
Excessive doses of [[Symphytine]], one of the PAs in comfrey, may cause [[cancer]] in rats. <ref>{{cite web |last = Rode | first = Dorena | url = http://www.comfreycentral.com/research/table5.htm | title = Summary of In Vivo Comfrey Studies |accessdate=2008-02-20 }}</ref> This was shown by injection of the pure alkaloid. The whole plant has also been shown to induce precancerous changes in '''transgenic''' rats. <ref>PMID: 17118137 BMC Bioinformatics. 2006 Sep 26;7 Suppl 2:S16 Analysis of gene expression changes in relation to toxicity and tumorigenesis in the livers of Big Blue '''transgenic''' rats fed comfrey (Symphytum officinale).
</ref>
== Fertilizer uses ==
Comfrey is a particularly valuable source of fertility to the organic gardener. It is very deep rooted and acts as a [[dynamic accumulator]], mining a host of nutrients from the soil. These are then made available through its fast growing leaves (up to 4-5 [[pound (mass)|pounds]] per plant per cut) which, lacking fibre, quickly break down to a thick black liquid. There is also no risk of nitrogen robbery when comfrey is dug into the soil as the [[Carbon to nitrogen ratio|C:N ratio]] of the leaves is lower than that of well-rotted compost. Comfrey is an excellent source of [[potassium]], an essential plant nutrient needed for [[flower]], [[seed]]s and [[fruit]] production. Its leaves contain 2-3 times more potassium than farmyard manure, mined from deep in the [[subsoil]], tapping into reserves that would not normally be available to plants.
There are various ways in which comfrey can be utilised as a fertiliser, these include:
*Comfrey for [[potato]]es - freshly cut comfrey should be wilted for a day or two, then laid along potato trenches about 2 inches deep. Avoid using flowering stems as these can root. The leaves will rapidly break down and supply potassium rich fertiliser for the developing potato plants.
*Comfrey as a [[compost activator]]- include 2-3 inch deep layers of comfrey in the compost heap to encourage [[bacterium|bacteria]]l activity and help to heat the heap. Comfrey should not be added in quantity as it will quickly break down into a dark sludgey liquid that needs to be balanced with more fibrous, carbon rich material.
*Comfrey liquid fertiliser- can be produced by either rotting leaves down in rainwater for 4-5 weeks to produce a ready to use 'comfrey tea', or by stacking dry leaves under a weight in a container with a hole in the base. When the leaves decompose a thick black comfrey concentrate is collected. This must be diluted at 15:1 before use.
*Comfrey as a [[mulch]]- a 2 inch layer of comfrey leaves placed around a crop will slowly break down and release plant nutrients. it is especially useful for crops that need extra potassium, such as tomatoes, and also fruit bushes like gooseberries and currants.
*Comfrey potting mixture- originally devised using peat, environmental awareness has led to a [[leaf mold]]-based alternative being adopted instead. Two year old, well decayed leaf mold should be used, this will absorb the nutrient-rich liquid released by the decaying comfrey.
*In a black plastic sack alternate 3-4 inch layers of leaf mould and chopped comfrey leaves. Add a little [[dolomite|dolomitic limestone]] to slightly raise [[Soil pH|pH]]. Leave for between 2-5 months depending on the season, checking that it does not dry out or become too wet. The mixture is ready when the comfrey leaves have rotted and are no longer visible. Use as a general potting compost, although it is too strong for seedlings.
== References==
{{reflist}}
==External links==
* [http://www.comfreycentral.com/ Comfrey Central - A Clearinghouse for Symphytum Information]
* [http://www.herballegacy.com/comfrey.html Contentions with Comfrey Studies]
* [http://www.bccancer.bc.ca/PPI/UnconventionalTherapies/Comfrey.htm British Columbia Cancer Agency on comfrey]
* [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?form=4&db=pubmed&dispmax=100&relentrezdate=No+Limit&term=comfrey PubMed/Medline]
* [http://www.itis.usda.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=32025 ITIS 32025] 2002-09-05.
*[http://linnaeus.nrm.se/flora/chk/lexs.htm NRM, Sweden] 2002-09-05.
* [http://www.ipni.org/ipni/IpniServlet?whole_name=&family=&infrafamily=&genus=symphytum&infragenus=&is_apni_record=on&species=&infraspecies=&is_gci_record=on&author_abbrev=&publication_title=&is_ik_record=on&include_authors=on&include_basionym_authors=on&query_type=by_query IPNI Symphytum] 2002-09-05.
*[http://hua.huh.harvard.edu/cgi-bin/Flora/taxon.pl?ACT=desc&FLORA_ID=11746&TAXON_ID=132030 Flora of China] 2002-09-05.
[[Category:Boraginaceae]]
[[Category:Herbs]]
[[Category:Medicinal plants]]
[[Category:Organic gardening]]
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