Hibiscus is a genus of flowering plants in the mallow family, Malvaceae. The genus is quite large, comprising several hundred species that are native to warm temperate, subtropical and tropical regions throughout the world. Member species are renowned for their large, showy flowers and those species are commonly known simply as "hibiscus", or less widely known as rose mallow. Other names include hardy hibiscus, rose of sharon, and tropical hibiscus.
The genus includes both annual and perennial herbaceous plants, as well as woody shrubs and small trees. The generic name is derived from the Greek name ἰβίσκος (ibískos) which Pedanius Dioscorides gave to Althaea officinalis (c. 40–90 AD).
A tea made from hibiscus flowers is known by many names around the world and is served both hot and cold. The beverage is known for its red colour, tart flavour, and vitamin C content.
The leaves are alternate, ovate to lanceolate, often with a toothed or lobed margin (dentate). The flowers are large, conspicuous, trumpet-shaped, with five or more petals, colour from white to pink, red, blue, orange, peach, yellow or purple, and from 4–18 cm broad.
Flower colour in certain species, such as H. mutabilis and H. tiliaceus, changes with age. The fruit is a dry five-lobed capsule, containing several seeds in each lobe, which are released when the capsule dehisces (splits open) at maturity. It is of red and white colours. It is an example of complete flowers.
Nyctinasty in Hibiscus
Nyctinasty is the circadian rhythmic nastic movement of plants in response to the onset of darkness, or a plant "sleeping". Hibiscus, a nyctinastic plant, has a circadian cycle in which they open their leaflets during the day, and close them at night. The movement of the hibiscus flower is accomplished through changes in electrolyte concentrations that cause water movement and changes in turgor pressure throughout the plant.
An initial stimulus such as lack of light on photoreceptors triggers an electrical signal to be propagated along neighboring cells in the plant. This causes a change in turgor pressure of specific cells at the pulvinus to allow for bending of the petals upward. Upon the stimulus calcium-permeable anion channels open to allow a flux of calcium ions into the cytoplasm of the cell causing it to depolarize. This electrical signal is propagated down the phloem to neighboring cells as sequential voltage calcium channels open. In response to the change in membrane potential voltage, gated potassium and chlorine channels open causing an efflux of ions. The increased concentration of ions outside of the cell creates an electrochemical gradient that pulls water out of the cell through osmosis. Aquaporins and hydrogen ion ATPase also help with the movement of water molecules. This causes a change in turgor pressure as water flows out of the flexor cells on the pulvinus and into the extensor cells to allow for bending of petals up to close the flower. The mechanism for hibiscus nyctinasty is an example of plant movement to improve fitness.
Not all plant species exhibit nyctinasty, some only observed in leaf movement while others in flowers. Nyctinasty in flowers alone can be split into a few subcategories: day blooming vs. night blooming, singular vs. repeated blooming cycle, or different combinations in between. In Genus Hibiscus we mostly observe singular day blooming flowers with some hybrids that can achieve repeating cycles. It is believed that the specific blooming cycle of flowers is a self-protective and reproductive mechanism, many species in the colder region close their flowers at night to prevent frosting while some desert species have night blooming flowers to prevent extensive water loss. Predators and Pollinators are also major factors contributing to blooming cycles; some flowers will close at night to prevent nocturnal predators in contrast with night blooming flowers that rely on nocturnal pollinators.
An experiment conducted by Darwin explored foliar nyctinasty to show it is an evolutionary mechanism to improve fitness. His experiments suggest FN can affect leaves' ability to balance their radiative heat by reducing exposure of the leaf to the cold night sky and increasing the exposure to other lateral plants that radiate more heat in order to avoid frost damage and stay warm. He performed experiments where he pinned the leaves of Oxalis and Trifolium down horizontally versus pinning the leaves down vertically to show that the horizontal, more exposed leaves displayed greater frost damage than the warmer, vertical counterparts.
Nyctinasty in hibiscus plants is a mechanism to protect against adverse conditions such as cool temperatures that can be damaging. Through a lack of light stimulus and circadian rhythms the plant is able to trigger the molecular movement of ions to allow for the closing of the flower.
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In temperate zones, probably the most commonly grown ornamental species is Hibiscus syriacus, the common garden hibiscus, also known in some areas as the "rose of Althea" or "rose of Sharon" (but not to be confused with the unrelated Hypericum calycinum, also called "rose of Sharon"). In tropical and subtropical areas, the Chinese hibiscus (H. rosa-sinensis), with its many showy hybrids, is the most popular hibiscus.
Several hundred species are known, including:
- Hibiscus abelmoschus L. synonym of Abelmoschus moschatus Medik.
- Hibiscus abelmoschus var. betulifolius Mast. synonym of Abelmoschus moschatus Medik.
- Hibiscus abelmoschus var. genuinus Hochr. synonym of Abelmoschus moschatus Medik.
- Hibiscus laevis abutiloides Willd. synonym of Talipariti tiliaceum var. pernambucense (Arruda) Fryxell
- Hibiscus abyssinicus Steud. (unresolved)
- Hibiscus acapulcensis Fryxell
- Hibiscus acerifolius Salisb. (unresolved)
- Hibiscus acerifolius DC. (unresolved)
- Hibiscus acetosaefolius DC. (unresolved)
- Hibiscus acetosella Welw. ex Hiern. false roselle
- Hibiscus acicularis
- Hibiscus aculeatus—comfortroot
- Hibiscus altissimus
- Hibiscus andongensis
- Hibiscus angolensis
- Hibiscus aponeurus
- Hibiscus archeri—Archer's hibiscus
- Hibiscus aridicola
- Hibiscus arnottianus A.Gray—kokiʻo ʻula (Hawaii)
- Hibiscus asper—bush roselle
- Hibiscus austroyunnanensis
- Hibiscus barbosae
- Hibiscus benguellensis
- Hibiscus berberidifolius
- Hibiscus bernieri
- Hibiscus bifurcatus—fork-bracted rosemallow
- Hibiscus biseptus—Arizona rosemallow
- Hibiscus bojerianus
- Hibiscus boryanus—foulsapate marron
- Hibiscus brackenridgei A.Gray—Hawaiian hibiscus maʻo hau hele
- Hibiscus burtt-davyi
- Hibiscus caerulescens
- Hibiscus caesius—dark-eyed hibiscus (South Africa)
- Hibiscus calyphyllus—lemonyellow rosemallow (tropical Africa)
- Hibiscus cameronii—Cameron's hibiscus, pink hibiscus
- Hibiscus cannabinus L.—Kenaf
- Hibiscus castroi
- Hibiscus cisplatinus—rosa del rio
- Hibiscus citrinus
- Hibiscus clayi O.Deg. & I.Deg.— Hawaiian red hibiscus (Hawaii)
- Hibiscus clypeatus—Congo mahoe
- Hibiscus coccineus (Medik.) Walter—scarlet rosemallow
- Hibiscus colimensis
- Hibiscus columnaris—mahot rempart
- Hibiscus comoensis
- Hibiscus congestiflorus
- Hibiscus costatus
- Hibiscus coulteri—desert rosemallow
- Hibiscus cuanzensis
- Hibiscus dasycalyx—Neches River rosemallow
- Hibiscus denudatus Benth.—pale face (Southwestern United States, Northwestern Mexico)
- Hibiscus dimidiatus
- Hibiscus dioscorides A.G.Mill. (Yemen)
- Hibiscus diplocrater
- Hibiscus diriffan A.G.Mill. (Yemen)
- Hibiscus diversifolius—swamp hibiscus
- Hibiscus dongolensis
- Hibiscus donianus
- Hibiscus elatus—mahoe
- Hibiscus elegans
- Hibiscus engleri—wild hibiscus
- Hibiscus escobariae
- Hibiscus excellii
- Hibiscus ferrugineus
- Hibiscus ficalhoanus
- Hibiscus flavoroseus
- Hibiscus fragilis DC.—mandrinette (Mascarene Islands)
- Hibiscus fragrans
- Hibiscus fritzscheae
- Hibiscus fugosioides
- Hibiscus furcellatus Desr.—lindenleaf rosemallow (Caribbean, Florida, Central America, South America, Hawaii)
- Hibiscus fuscus
- Hibiscus genevii Bojer (Mauritius)
- Hibiscus gilletii
- Hibiscus gossweileri
- Hibiscus grandidieri
- Hibiscus grandiflorus Michx.—swamp rosemallow (Southeastern United States)
- Hibiscus grandistipulatus
- Hibiscus grewiifolius
- Hibiscus hamabo
- Hibiscus hastatus
- Hibiscus heterophyllus—native rosella
- Hibiscus hirtus—lesser mallow
- Hibiscus hispidissimus
- Hibiscus huellensis
- Hibiscus hybridus
- Hibiscus indicus
- Hibiscus insularis Endl.—Phillip Island hibiscus (Phillip Island)
- Hibiscus integrifolius
- Hibiscus jaliscensis
- Hibiscus kochii
- Hibiscus kokio—red rosemallow
- Hibiscus labordei
- Hibiscus laevis All. (=H. militaris)—halberd-leaved rosemallow (central and eastern North America)
- Hibiscus lasiocarpos—woolly rosemallow
- Hibiscus lasiococcus
- Hibiscus lavaterioides
- Hibiscus laxiflorus
- Hibiscus leptocladus ([Northwest Australia])
- Hibiscus leviseminus
- Hibiscus lilacinus—lilac hibiscus
- Hibiscus liliiflorus—Rodrigues tree hibiscus
- Hibiscus longifolius
- Hibiscus longisepalus
- Hibiscus ludwigii
- Hibiscus lunariifolius
- Hibiscus macilwraithensis - Australia
- Hibiscus macrogonus
- Hibiscus macrophyllus—largeleaf rosemallow
- Hibiscus macropodus
- Hibiscus makinoi—Okinawan hibiscus
- Hibiscus malacophyllus Balf.f. (Yemen)
- Hibiscus malacospermus
- Hibiscus martianus— heartleaf rosemallow
- Hibiscus mesnyi Pierre ex Laness. (Vietnam endemic)
- Hibiscus moscheutos L.—crimsoneyed rosemallow (Central and Eastern North America)
- Hibiscus mutabilis L.—cotton rosemallow, Confederate rose (East Asia)
- Hibiscus paramutabilis
- Hibiscus pedunculatus
- Hibiscus pernambucensis—seaside mahoe
- Hibiscus phoeniceus—Brazilian rosemallow
- Hibiscus platanifolius
- Hibiscus quattenensis
- Hibiscus poeppigii—Poeppig's rosemallow
- Hibiscus radiatus—monarch rosemallow
- Hibiscus rosa-sinensis L.—Chinese hibiscus (East Asia)
- Hibiscus sabdariffa L.—roselle, omutete, or sorrel
- Hibiscus schizopetalus—fringed rosemallow
- Hibiscus scottii
- Hibiscus socotranus
- Hibiscus sinosyriacus
- Hibiscus splendens
- Hibiscus stenanthus Balf.f. (Yemen)
- Hibiscus striatus—striped rosemallow
- Hibiscus sturtii Australia
- Hibiscus syriacus L. (type species)—rose of Sharon (Asia)
- Hibiscus taiwanensis S.Y. Hu[circular reference]
- Hibiscus tiliaceus L.—sea hibiscus (Australia, Southeast Asia, Oceania)
- Hibiscus tozerensis - Australia
- Hibiscus trilobus—threelobe rosemallow
- Hibiscus trionum L.—flower-of-an-hour
- Hibiscus vitifolius—tropical rose mallow
- Hibiscus waimeae A.Heller—kokiʻo keʻokeʻo (Hawaii)
Formerly placed in the genus
- Abelmoschus esculentus (L.) Moench (as H. esculentus L.)
- Abelmoschus ficulneus (L.) Wight & Arn. (as H. ficulneus L.)
- Abelmoschus manihot subsp. manihot (as H. manihot L.)
- Abelmoschus manihot var. pungens (Roxb.) Hochr. (as H. pungens Roxb.)
- Abelmoschus manihot var. tetraphyllus (Roxb. ex Hornem.) Borss. Waalk. (as H. tetraphyllus Roxb. ex Hornem.)
- Abelmoschus moschatus subsp. moschatus (as H. abelmoschus L.)
- Abelmoschus moschatus subsp. tuberosus (Span.) Borss. Waalk. (as H. sagittifolius Kurz)
- Alyogyne cuneiformis (DC.) Lewton (as H. cuneiformis DC.)
- Alyogyne hakeifolia (Giord.) Alef. (as H. hakeifolius Giord.)
- Alyogyne huegelii (Endl.) Fryxell (as H. wrayae Lindl.)
- Alyogyne pinoniana (Gaudich.) Fryxell (as H. pinonianus Gaudich.)
- Firmiana simplex (L.) W.Wight (as H. simplex L.)
- Lagunaria patersonia subsp. patersonia (as H. patersonius Andrews)
- Kosteletzkya adoensis (Hochst. ex A. Rich.) Mast. (as H. adoensis Hochst. ex A.Rich.)
- Kosteletzkya pentacarpos (L.) Ledeb. (as H. pentacarpos L.)
- Kosteletzkya tubiflora (DC.) Blanch. & McVaugh (as H. tubiflorus DC.)
- Kosteletzkya virginica (L.) C.Presl ex A.Gray (as H. virginicus L.)
- Pavonia arabica Hochst. & Steud. ex Boiss. (as H. flavus Forssk.)
- Pavonia spinifex (L.) Cav. (as H. spinifex L.)
- Radyera farragei (F.Muell.) Fryxell & S.H.Hashmi (as H. farragei F.Muell.)
- Thespesia lampas (Cav.) Dalzell (as H. lampas Cav.)
- Thespesia populnea (L.) Sol. ex Corrêa (as H. populneoides Roxb. or H. populneus L.)
Hibiscus is a very hardy, versatile plant and in tropical conditions it can enhance the beauty of any garden. Being versatile it adapts itself easily to balcony gardens in crammed urban spaces and can be easily grown in pots as a creeper or even in hanging pots. It is a perennial and flowers through the year. As it comes in a variety of colors, it's a plant which can add vibrancy to any garden.
The only infestation that gardeners need to be vigilant about is mealybugs. Mealybug infestations are easy to spot as they are clearly visible as a distinct white cottony infestation on buds, leaves or even stems. To protect the plant you need to trim away the infected part, spray with water, and apply an appropriate pesticide.
Rope and construction
The inner bark of the sea hibiscus (Hibiscus tiliaceus), also called 'hau', is used in Polynesia for making rope, and the wood for making canoe floats. The ropes on the missionary ship Messenger of Peace were made of fibres from hibiscus trees.
The tea made of the calyces of Hibiscus sabdariffa is known by many names in many countries around the world and is served both hot and cold. The beverage is well known for its red colour, tartness and unique flavour. Additionally, it is highly nutritious because of its vitamin C content.
It is known as bissap in West Africa, "Gul e Khatmi" in Urdu & Persian, agua de jamaica in Mexico and Central America (the flower being flor de jamaica) and Orhul in India. Some refer to it as roselle, a common name for the hibiscus flower. In Jamaica, Trinidad and many other islands in the Caribbean, the drink is known as sorrel (Hibiscus sabdariffa; not to be confused with Rumex acetosa, a species sharing the common name sorrel). In Ghana, the drink is known as soobolo in one of the local languages.
In Cambodia, a cold beverage can be prepared by first steeping the petals in hot water until the colors are leached from the petals, then adding lime juice (which turns the beverage from dark brown/red to a bright red), sweeteners (sugar/honey) and finally cold water/ice cubes.
In Egypt, hibiscus tea is known as karkadé (كركديه), and is served as both a hot and a cold drink.
Hibiscus (also known in Sri Lanka as shoe flower, සපත්තු මල, වද මල in Sinhalese) is an ingredient with a rich heritage of refreshing Lankans. Fresh juices, ice teas and syrups made of the Hibiscus flower are famous refreshments among Sri Lankans.
Dried hibiscus is edible, and it is often a delicacy in Mexico. It can also be candied and used as a garnish, usually for desserts.
The roselle (Hibiscus sabdariffa) is used as a vegetable. The species Hibiscus suratensis Linn synonymous with Hibiscus aculeatus G. Don is noted in Visayas in the Philippines as being a souring ingredient for almost all local vegetables and menus. Known as labog in the Visayan area, (or labuag/sapinit in Tagalog), the species is an ingredient in cooking native chicken soup.
Claimed effects on blood pressure
Precautions and contraindications
Pregnancy and lactation
While the mechanism is not well understood, previous animal studies have demonstrated both an inhibitory effect of H. sabdariffa on muscle tone and the anti-fertility effects of Hibiscus rosa-sinensis, respectively. The extract of H. sabdariffa has been shown to stimulate contraction of the rat bladder and uterus; the H. rosa-sinensis extract has exhibited contraceptive effects in the form of estrogen activity in rats. These findings have not been observed in humans. The Hibiscus rosa-sinensis is also thought to have emmenagogue effects which can stimulate menstruation and, in some women, cause an abortion. Due to the documented adverse effects in animal studies and the reported pharmacological properties, the H. sabdariffa and H. rosa-sinensis are not recommended for use during pregnancy.
It is postulated that H. sabdariffa interacts with diclofenac, chloroquine and acetaminophen by altering the pharmacokinetics. In healthy human volunteers, the H. sabdariffa extract was found to reduce the excretion of diclofenac upon co-administration. Additionally, co-administration of Karkade (H. sabdariffa), a common Sudanese beverage, was found to reduce chloroquine bioavailability. However, no statistically significant changes were observed in the pharmacokinetics of acetaminophen when administered with the Zobo (H. sabdariffa) drink. Further studies are needed to demonstrate clinical significance.
Symbolism and culture
The red hibiscus is the flower of the Hindu goddess Kali, and appears frequently in depictions of her in the art of Bengal, India, often with the goddess and the flower merging in form. The hibiscus is used as an offering to the goddess Kali and the god Ganesha in Hindu worship.
In the Philippines, the gumamela (the local name for hibiscus) is used by children as part of a bubble-making pastime. The flowers and leaves are crushed until the sticky juices come out. Hollow papaya stalks are then dipped into this and used as straws for blowing bubbles. Together with soap, hibiscus juices produce more bubbles. Also called "Tarukanga" in Waray particularly in Eastern Samar province.
The hibiscus flower is traditionally worn by Tahitian and Hawaiian girls. If the flower is worn behind the left ear, the woman is married or has a boyfriend. If the flower is worn on the right, she is single or openly available for a relationship. The yellow hibiscus is Hawaii's state flower.
The bark of the hibiscus contains strong bast fibres that can be obtained by letting the stripped bark set in the sea to let the organic material rot away.
As a national and state symbol
The hibiscus is a national symbol of Haiti, and the national flower of nations including the Solomon Islands and Niue. Hibiscus syriacus is the national flower of South Korea, and Hibiscus rosa-sinensis is the national flower of Malaysia. Hibiscus brackenridgei is the state flower of Hawaii.
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|Wikispecies has information related to Hibiscus.|
|Wikimedia Commons has media related to Hibiscus.|
- American Hibiscus Society (AHS)
- Australian Hibiscus Society
- International Hibiscus Society
- Vicki J. Coldwell Plant and care Hibiscus
- Foundation for Revitalisation of Local Health Traditions
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