Senna (genus) Totally Explained

Everything about Senna Genus totally explained

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. The species were reassigned by Howard Samuel Irwin and Rupert Charles Barneby, but this process isn't 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).(External Link

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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
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)

In medicine

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 for example 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. As regards other chemicals, the antiinflammatory compound resveratrol was first isolated from S. quinquangulata, 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're 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.

Selected species

Senna acclinis (F.Muell.) Randell

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.) Randell

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.) Randell

Senna didymobotrya (Fresen.) H.S.Irwin & Barneby

Senna domingensis

Senna excelsa (Schrad) Irwin & Barneby

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

Senna heptanthera (F.Muell.) Randell

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.) Randell

Senna marilandica (L.) Link

Senna martiana (Benth.) H.S.Irwin & Barneby

Senna martiana (Schrad) Irwin & Barneby

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.) Randell

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.) Randell

Senna oligophylla

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.) Randell

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)

Senna spectabilis

Senna spectabilis var. excelsa
Senna spectabilis var. micans - sometimes placed in Senna macranthera

Senna splendida (Vogel) H.S.Irwin & Barneby

Senna surattensis (Burm.f.) H.S.Irwin & Barneby (= S. speciosa Roxb.)

Senna sylvestris (Vell.) H.S.Irwin & Barneby

Senna sylvestris var. bifaria H.S.Irwin & Barneby

Senna timoriensis (DC.) H.S.Irwin & Barneby

Senna tora L. – Sickle Wild Sensitive-plant

Senna trolliiflora

Senna undulata (Vahl) H.S.Irwin & Barneby

Senna venusta (F.Muell.) Randell

Senna wislizeni – Wislizenus' Senna, Shrubby Senna

Footnotes

Further Information

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