Senna (genus)

Taxobox
name = "Senna"

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image_width = 200px
image_caption = "Caesalpinia exostemma" ssp. exostemma inflorescence, Guanacaste (Costa Rica)
regnum = Plantae
divisio = Magnoliophyta
classis = Magnoliopsida
subclassis = Rosidae
unranked_ordo = Eurosids I
ordo = Fabales
familia = Fabaceae
subfamilia = Caesalpinioideae
tribus = Cassieae
subtribus = Cassiinae
genus = "Senna"
genus_authority = Mill.
subdivision_ranks = Species
subdivision = Around 250, see text
synonyms ="Cathartocarpus" ("partim")
"Chamaefistula"
"Diallobus" "Earleocassia"
"Herpetica"
"Isandrina"
"Palmerocassia"
"Pseudocassia"

"Senna" (from Arabic "sanā"), the sennas, is a large genus of around 250 species of flowering plants in the family Fabaceae, subfamily Caesalpinioideae. This diverse genus is native throughout the tropics, with a small number of species reaching into temperate regions. Almost all species were at one time or another placed in "Cassia", a close relative which until recent decades served as a "wastebin taxon" to hold all Cassiinae. [ILDIS (2005)] The species were reassigned by Howard Samuel Irwin and Rupert Charles Barneby, but this process is not entirely complete and some corrections may still take place.

Typically "Senna" species have yellowish flowers. They may be herbs, smallish trees or even a kind of liana, but typically are shrubs or subshrubs.

Ecology and uses

"Senna" species make good ornamental plants and are used for landscape gardening. The wide variety of species and ecological adaptations makes at least a handful of sennas suitable for any climate warmer than cool-temperate.

Cassia gum - a commonly-used thickening agent -, despite its name is actually from Chinese Senna ("S. obtusifolia") seeds. In some Southeast Asian cuisines (particularly those of Thailand and Laos), the leaves and flowers of Siamese Senna ("S. siamea", called "khi-lek" in Thai), either fresh or pickled in brine, are used in cooking, particularly in "gaeng khi-lek" ("khi-lek" curry). [http://www.thai4uk.com/acatalog/shop.html?http%3A//www.thai4uk.com/acatalog/Vegetables_Herbs.html&CatalogBody] [http://eatingasia.typepad.com/eatingasia/2005/09/gaeng_ki_lek_on.html] .

Another senna, "Senna italica" ssp. "italica" (= "Cassia obovata"), often called "neutral henna", is used as a hair treatment with effects similar to henna but without the red color. The active component is an anthraquinone derivative called chrysophanic acid, which is also found in higher concentrations in rhubarb root. It adds a slight yellow color.
Some species of "Senna" are notable for being host to caterpillars of certain Lepidoptera species, for example:
* "Ascalapha odorata" (Black Witch Moth) – recorded on Candle Bush ("S. alata")
* "Astraptes fulgerator" (Two-barred Flasher) – recorded on Candle Bush ("S. alata"), "S. cobanensis", "S. hayesiana", "S. pallida", "S. papillosa", "S. undulata" and probably others [Hébert "et al." (2004) refer to "Cassia emarginata", which today is either of "Chamaecrista pilosa", Rambling Senna ("S. bicapsularis") or "Senna candolleana". The last does not occur in their study area; given the general importance of "Senna" species and the lack of records for "Chamaecrista" species as foodplants in the study area, "S. bicapsularis" seems to be the plant in question. See also Brower (2006).]
* "Catopsilia pomona" (Common Emigrant, Lemon Emigrant) – recorded on Candle Bush ("S. alata") and possibly others
* "Catopsilia pyranthe" (Mottled Emigrant) – recorded from Candle Bush ("S. alata"), Avaram Senna ("S. auriculata"), "S. garrettiana" and probably others
* "Phoebis sennae" (Cloudless Sulphur)Verify source|date=December 2007

In medicine

Senna is currently used in medicine as a laxative.

Sennas have for millennia played a major role in herbalism and folk medicine. Alexandrian Senna ("S. alexandrina") was and still is a significant item of trans-national trade e.g. by the Ababdeh people and grown commercially, traditionally along the middle Nile but more generally in many regions around the northwestern Indian Ocean.

Sennas act as purgatives and are similar to aloe and rhubarb in having as active ingredients anthraquinone derivatives and their glucosides. The latter are called sennosides or senna glycosides. "Senna" acts on the lower bowel, and is especially useful in alleviating constipation. It increases the peristaltic movements of the colon. The plants are most often prepared as an infusion. Senna glycosides are listed as ATC code A06AB06 on their own and A06AB56 in combined preparations.

[
thumb|right|200px|Resveratrol was first isolated from "Senna quinquangulata"] As regards other chemicals, the antiinflammatory compound resveratrol was first isolated from "S. quinquangulata",Fact|date=June 2008 and Siamese Senna "S. siamea" contains barakol used to counteract aconitine poisoning. Chinese Senna ("S. obtusifolia") seeds are also used in Kampō (traditional Japanese medicine) where they are called "ketsumei-shi" (ケツメイシ, 決明子) or by their Chinese name "jué míng zǐ" (traditional: 決明子, simplified: 决明子).

The long-standing use of (mainly) Alexandrian Senna is reflected by its presence in many herbal remedies and tonics. These include for example Black draught, Catholicon, Daffy's Elixir, Diasenna (literally meaning "composed of senna") and Swedish bitters. On the other hand, it was contained in more dangerous "medications" such as the highly toxic antihelminthic Lumbricide and - because their purgative effects are a readily-observed "proof" that some concoction "works" - many generally useless and often poisonous "patent medicine".

Today, because of the presence of ample anthraquinones, sennas are still used as the primary ingredient in certain commercial stimulant laxatives. Senna is also the primary ingredient found in most "dieter's teas". The combination of acting as a stimulant which reduces a dieter's appetite, and the laxative properties that cause food to move through their system before as many calories can be absorbed is a combination that can lead to rapid and even dangerous weight loss.

The stimulant action of sennosides should be taken into account for those who suffer from any conditions where stimulants are contraindicated, such as past heart disease, high blood pressure, anxiety attacks, etc. A (generally invisible and harmless) side effect of taking "Senna" medication regularly is Melanosis coli, a brown discoloration of the colon wall.

elected species

* "Senna acclinis" (F.Muell.) RandellVerify source|date=December 2007
* "Senna aculeata" (Benth.) H.S.Irwin & Barneby
* "Senna alata" – Candle Bush, Candelabra Bush, Empress Candle Plant, Candlestick Tree, Ringworm Tree, "candletree"
* "Senna alexandrina" – Alexandrian Senna, Egyptian Senna, Tinnevelly Senna, East Indian Senna, "sene de la palthe" (French)
* "Senna angulata" (Vogel) H.S.Irwin & Barneby
* "Senna appendiculata" (Vogel) Wiersema (= "S. australis")
* "Senna armata" (S.Watson) H.S.Irwin & Barneby
* "Senna artemisioides" – Silver Senna, Feathery Senna
* "Senna auriculata" – Avaram Senna, "avaram", "ranawara"
* "Senna aversiflora" (Herbert) H.S.Irwin & Barneby
* "Senna bicapsularis" – Rambling Senna, Christmas Bush, Money Bush, Yellow Candlewood
* "Senna birostris" (Vogel) H.S.Irwin & Barneby
* "Senna candolleana" (Vogel) H.S.Irwin & Barneby
* "Senna cardiosperma" (F.Muell.) RandellVerify source|date=December 2007
* "Senna caudata"
* "Senna cobanensis" (Britton & Rose) H.S.Irwin & Barneby
* "Senna corymbosa" – Argentine Senna, Argentina Senna, Buttercup Bush, Flowering Senna, (Texas) Flowery Senna, Tree Senna
* "Senna covesii" – Desert Senna, Coues' Senna, Rattleweed
* "Senna cumingii" (Hook. & Arn.) H.S.Irwin & Barneby
* "Senna cuthbertsonii" (F.Muell.) RandellVerify source|date=December 2007
* "Senna didymobotrya" (Fresen.) H.S.Irwin & Barneby
* "Senna domingensis"
* "Senna excelsa" (Schrad) Irwin & BarnebyVerify source|date=December 2007
* "Senna fruticosa" (Mill.) H.S.Irwin & Barneby
* "Senna garrettiana" (Craib) H.S.Irwin & Barneby
* "Senna gaudichaudii" (Hook. & Arn.) H.S.Irwin & Barneby
* "Senna hayesiana" (Britton & Rose) H.S.Irwin & Barneby
* "Senna hebecarpa" – American Senna, Wild Senna
* "Senna helmsii"Verify source|date=December 2007
* "Senna heptanthera" (F.Muell.) RandellVerify source|date=December 2007
* "Senna hirsuta" (L.) H.S.Irwin & Barneby
** "Senna hirsuta" var. "puberula"
* "Senna italica" Mill.
** "Senna italica" ssp. "italica" – Neutral Henna
* "Senna ligustrina" (L.) H.S.Irwin & Barneby
* "Senna lindheimeriana" (Scheele) H.S.Irwin & Barneby – Velvet-leaved Senna
* "Senna macranthera" (Collad.) H.S.Irwin & Barneby
** "Senna macranthera" var. "macranthera"
* "Senna magnifolia" (F.Muell.) RandellVerify source|date=December 2007
* "Senna marilandica" (L.) Link
* "Senna martiana" (Benth.) H.S.Irwin & Barneby
* "Senna martiana" (Schrad) Irwin & BarnebyVerify source|date=December 2007
* "Senna multiglandulosa" (Jacq.) H.S.Irwin & Barneby
* "Senna multijuga" (Rich.) H.S.Irwin & Barneby
** "Senna multijuga" var. "lindleyana" (Gardner) H.S.Irwin & Barneby
* "Senna nicaraguensis" (Benth.) H.S.Irwin & Barneby
* "Senna nitida" (Rich.) H.S. Irwin & Barneby
* "Senna notabilis" (F.Muell.) RandellVerify source|date=December 2007
* "Senna obtusifolia" – Chinese Senna, Sicklepod, Foetid Senna, Sickle Senna, Coffeeweed, Arsenic Weed, "blunt-leaved senna", "coffee pod", "java bean"
* "Senna occidentalis" – Coffee Senna, Mogdad Coffee
* "Senna odorata" (R. Morris) Randall
* "Senna oligoclada" (F.Muell.) RandellVerify source|date=December 2007
* "Senna oligophylla"Verify source|date=December 2007
* "Senna pallida" (Vahl) H.S.Irwin & Barneby
* "Senna papillosa" (Britton & Rose) H.S.Irwin & Barneby
* "Senna pendula" (Willd.) H.S.Irwin & Barneby
** "Senna pendula" var. "stahlii" (Urb.) Irwin & Barneby
* "Senna pleurocarpa" (F.Muell.) RandellVerify source|date=December 2007
* "Senna purpusii" (Brandegee) H.S.Irwin & Barneby
* "Senna rugosa" (G.Don.) H.S.Irwin & Barneby
* "Senna scandens"
* "Senna septemtrionalis" (Viv.) H.S.Irwin & Barneby
* "Senna siamea" (Lam.) H.S.Irwin & Barneby – Siamese Senna, "khi-lek" (Thai)