Herbs from Distant Lands: Callistemon viminalis and Callistemon citrinus - Weeping Bottlebrush and Lemon Scented Bottlebrush

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PLANT PROFILE

Callistemon is genus of plants that consist of 40 species of evergreen shrubs and trees, it belongs to family of Myrtaceae, and all of the species are endemic to Australia. Two of its species - Callistemon viminalis and Callistemon citrinus are nowadays grown worldwide. As it was distributed as a ornamental plants thanks to beauty of its deep red flowers with interesting structure.
And to many communities in different countries, with the plants came the information about how Australian Aborigine has used it in their traditional healing. But sadly majority of people that grows C. viminalis or C. citrinus in their tropical, subtropical or warm temperate gardens, or in pots in colder climate regions. Never heard about how tasty and healthy is the tea made from Callistemon leaves or flowers. Even most of Australians never knew it.
But its limited yet significant popularity as a medicinal plant among folk healers and herbalists in some countries. Attracted attention on many scientists, and lots of studies has been conducted to identify these Callistemons chemical compound. And tests its biological and pharmacological actions, to validate claims of traditional medicine, or find its new clinical applications.

Callistemon viminalis and Callistemon citrinus plants are so similar, that the two species are often mistaken even by botanists. The two, cross-pollinate easily with each other and other Callistemon species, creating many different hybrids. And also its appearance may differ due to climate differences. But generally it is considered that Callistemon viminalis can reach more than 10 m in height, and has slender, pendulous young stems, which are giving it strongly weeping outlook. While Callistemon citrinus grows usually relatively smaller, to around 4 m, and its young branches are a bit weeping, but thicker, more stiff and upright than those of C. viminalis.
The other significant difference between the two species is that if you crush its leaves, the leaves of C. citrinus will have more lemony scent than the scent of C. viminalis leaves. Both plants aroma can be described as a unique mix of eucalyptuses, citruses and pines fragrances (that vary due to ancestry, soil, climate, season, etc.), and it makes tea from it very invigorating, uplifting and relaxing.

Callistemon viminalis is most commonly called Weeping Bottlebrush. Its botanical synonyms include Melaleuca viminalis and Metrosideros viminalis.
Callistemon citrinus is commonly called Lemon Scented Bottlebrush, Crimson Bottlebrush, Red Bottle Brush or Lemon Bottle Brush. Its non-english vernacular names can sometimes also relate to Callistemon viminalis, here are some of it : Naaglingam, Shiv-lingi (Sanskrit), Cheel, Kastula (Hindi), Muthuga (Kannada), Palasu (Tamil), Seesa Brush (Telugu), Khakda, Khakra (Gujarathi), Sumbul, Simal (Urdu), Kalki Phool (Nepali), Kuflik (Polish), Tram Bong Do (Vietnamese).
Callistemon citrinus is also known as Callistemon lanceolatus, this name can be contemporarily found in many scientific sources from India, Bangladesh and Pakistan, other botanical synonyms of this plant include Melaleuca citrina, Callistemon laevis and Metrosideros citrine.

CULTIVATION AND HARVESTING

Callistemon viminalis and Callistemon citrinus are evergreen trees that originate from eastern parts of Australia, including coastal areas. But has been introduced and naturalized in many subtropical, tropical and warm temperate regions around the globe (some says that older plants of C. citrinus can survive frosts even up to - 10°C, but C. viminalis is said to be less frost resistant ). And in some parts of USA and Africa it even become invasive species.
Both species can grow on many kind of soils, including heavy clay and sands, but prefers sandy loam and dislikes highly alkaline soils. Callistemons are strongly wind resistant, and therefore often planted as a wind brakes. It is also used for prevention of soil erosion, and often planted on roadsides due to fact of its smog tolerance.
It likes humid climate, and most of sources says that C. citrinus prefer moist but well drained soils, while C. viminalis likes to grow close to water bodies, although in Australia C. citrinus is recorded growing in swampy areas, so both species are not afraid of waterlogged soil. But both species are also strongly drought resistant when established, and immune to dry air and scorching sun. It can grows best under full sun or in half shade, in strong shade it can grow well, but it will not flower as abundantly as in sunny places. The main intensive flowering generally takes time during dry months, which means different time of year in different regions, and in some might occur twice a year. But in Australia C. viminalis is also recorded to produce small amount of flowers all year round.
The fruit-capsules that contain seeds can remain on C. citrinus stems even for seven years, keeping its seeds enclosed until stimulated by the plant's death or fire exposure. While C. viminalis drops its own seeds after around a year. The plants can be propagated threw seeds or woody cuttings. But only cuttings as a clones guarantee that the new plants will have look and chemotype of mother plant, which is especially important in cases of its many different cultivars, like dwarf C. viminalis 'Captain Cook'. Offspring from the seeds might be cross of mother plant with other Callistemon species as all Callistemons species easily pollinate other, or it might differ from its parents due to mutation.
Callistemon flowers are rich in nectar and favored by different types of honey bees, therefore the plants can be source of honey even on commercial scale. Freshly opened, clean flowers are picked and dipped in water to release its nectar. But to make sweet drink you can also use old method of Aborigines, and slowly pour water over the flowers that hangs on stems, holding receptive bowl under. The leaves can be harvested at any time of year, but the one picked during rainy months and shortly after will contain less essential oils. Therefore it will make less aromatic and less medicinally potent tea. The leaves have to be fully matured, tough and greyish green. Young, still soft and bright green leaves are not good.
Callistemons are low maintenance plants, you don't have to prune it at all, it will always look good without it. But if you want to shape it a bit or curb its size (those plants are great for bonsai), then you should do it after flowering period or at least two months before flowering season. Otherwise you might cut off the stems that was about to flower. The young growth is not creating flowers. Also hard pruning of Callistemons might force them to put more energy into growth of new stems instead of generation of flowers, for long months. But if there is a need, you can cut even big old Callistemon trees down to the roots. As it posses remarkable ability to regenerate and quickly regrow from the scratch.

All Callistemons can suffer from attacks of scale insects, but its extracts has show insecticidal activity against some plants pests insects species like Aphis, and moluscicidal against some species of snails like Biomphalaria.
Leaf and twigs essential oil of C. viminalis demonstrated strong acaricidal and repellent activities on two-spotted spider mites.

The essential oil of C. viminalis showed moderate or strong activity in killing of the stored-grain insects : Sitophilus oryzae, Tribolium castaneum, Rhyzopertha dominica, Ephestia kuehniella, Acanthoscelides obtectus and Callosobruchus maculatus. And C. lanceolatus is claimed effective for control of rice moth Corcyra cephalonica.
C. viminalis leaf extracts observed a strong larvicide activity against larvae of mosquito Aedes albopictus.

Leptospermone, natural compound obtained from roots of C. citrinus, was found to be phytotoxic and caused bleaching of grass and broadleaved weeds, while maize was found to be resistant to it. Mesotrione, synthetically derived from leptospermone is used as a herbicide to control broadleaved weeds in maize crop. Also essential oil extracted from C. viminalis exhibited selective phytotoxic effects, and due to its biodegradable nature may be used for development of ecologic herbicides.
Eucalyptol also known as 1,8 - cineole is well known as an allelopathic agent (it negatively affect germination and growth of weeds). Essential oils of both C. viminalis and C. citrinus are rich in eucalyptol, which mostly make up more than 50% of the oils.

Callistemon citrinus flower extract can be used as a natural alternative to synthetic pH indicators (and probably Callistemon flowers from all red flowered species are just as good for it). It gives precise results same as Phenolphthalein indicator and hence can replace its application in volumetric titrations. Callistemon flowers are cleaned with tap water and then with distilled water. Dried in shade and crushed in mortar. Then extract is prepared using distilled water, filtered with filter paper and stored in air-tight container at 4ºC.

Callistemon wood is very hard and is used to make tools handles, etc. It is also used as a fuel.

CULINARY USES

Both Callistemon viminalis and Callistemon citrinus leaves and flowers are used to make a very pleasant teas (probably all Callistemon species can be used for this purpose, with more or less similar if not identical flavor, but I don't have enough information to make that claim). The leaves can be dried and crushed or used fresh straight from the tree, but then need to be chopped well straight before pouring hot water on it. It need to steep under tight cover to avoid evaporation of leaves essential oils, which gives Callistemon leaf tea its whole charm. As this tea is all about the aroma. It tastes just mild, slightly bitter, but its aroma is unique and rich, with significant notes of eucalyptus, citruses and pines. Callistemon citrinus tea aroma is usually more citrusy as its name indicate, than the one from leaves of C. viminalis. Both teas are equally pleasurable warm or cold, and combine well with sweet and sour fruit juices. It is very revitalizing, uplifting, mildly stimulating and relaxing in the same time.
The fresh Callistemon flowers infusions are much less aromatic but much sweeter. The flowers itself can be put into any kind of drink to act as a sweetener. Australian Aborigenes often just sucked the nectar from Callistemon flowers, or slowly and continuously pour water over branches with lots of flowers, so that it was dripping together with nectar into bowl under.

Dr. Mark "Merriwether" Vorderbruggen on his blog Foraging Texas is suggesting that : '' You can also use the leaves and flowers of the bottlebrush tree similar in manner to bay or rosemary leaves. Add several to a sauce, stew, or roasting meat to add an exotic flavor.'' I never tried yet to use Callistemon as a spice, but I certainly will and write here my experience.

Scientists recommend C. citrinus essential oil and methanolic or hydromethanolic extracts as botanical preservative. That protect food products from fast spoiling, while being healthy in consumption unlike synthetic preservatives that has adverse effects on our wellbeing.

Callistemon leaves are rich in Eucalyptol, essential oils constituent characteristic to Eucalyptus plants and Bay Laurel Leaf. Although it is used for flavoring in food production as well as in medicines, and posses a lots of medicinal properties. Eucalyptol is also known for long list of side effects of it's excessive consumption. Therefore moderation in any form of consumption of Callistemons is a must.

COSMETIC USES

In South Korea, study has been made to evaluate potential of Callistemon citrinus as skin anti-ageing cosmetics ingredient. Authors of the study has concluded that due to fact that extracts of C. citrinus exhibited strong anti-elastase and strong antioxidant activity, this plant could be potential candidate for the development of novel cosmetic additives.
Mashed Callistemon leaves are traditionally rubbed on the skin to drive away insects, the leaves are also kept between clothes and beddings to keep it bugs free (The essential oil obtained from C.
viminalis exhibited insecticidal activities).
Considered both skin aging protection combined with insects repellent properties, the fact it kills all kinds of skin infecting microbes, and of course it's wonderful fragrance, Callistemons indeed seems to be a great ingredients for skin creams and other cosmetics.

MEDICINAL USES

Callistemons has been used in healing practices of Australian Aborigines since times immemorial. Callistemon viminalis and Callistemon citrinus are the most popular species of the genus, as it has been brought from Australia to many countries worldwide, to some more than 200 years ago. And therefore the both species are best known for its use in traditional medicine by folk healers and herbalists, not only in Australia but in other countries too. And are best researched from all of Callistemon species. As many scientific phytochemical and pharmacological tests on those two species (some of which resulted in development of new pharmaceutical drugs) was conducted in India, Pakistan and Bangladesh, some also in countries like Iraq, Iran, Egypt, Korea, Japan, Vietnam, and even few in Australia.
Yes, it seems funny and sad in the same time that not many Australian scientists seems to be interested in medicinal potential of their native plants. And according to my knowledge Callistemon healing properties are much less known to Australian users of herbs, than those of most of the herbs brought to their continent from Europe. And although in many local communities around the world C. viminalis or C. citrinus are seen as an important herbal cure. Majority of the owners of those plants keep it only for ornamental uses, totally unaware of its health benefits or at least the fact that tea made from it tastes great. Which makes it one of the most underutilized medicinal plants, among those that has been well researched and poses many scientifically identified properties, verified traditional claims and have been proved safe.

Ethnobotanical records and results of phytochemical and pharmacological tests are proving that Callistemon viminalis and Callistemon citrinus are close to identical not only by its outlook, but also by its medicinal actions, which is : antioxidant, antibacterial (to both Gram-positive and Gram-negative), antifungal, antiviral, anticough, anti-inflammatory, astringent, diuretic, antidiabetic, anthelmintic, relaxant, neuroprotective, analgesic, anticancer, antidiarrhoeal, vulnerary, hepatoprotective, cardioprotective, antispasmodic, hypolipidemic, it also inhibits cholinesterase and elastase enzymes.
Flavonoid compounds isolated from Callistemon viminalis have the ability to inhibit the platelets aggregation (Anti thrombotic effect) and encourages the dilation of blood vessels.
Although in Traditional Chinese Medicine terms Callistemons are considered to be of neutral temperature qualities, I would say that they have rather cooling properties.

Callistemon viminalis and Callistemon citrinus are commonly used as mutual substitutes. Infusions of its leaves alone or leaves with flowers are traditionally used to treat :

- Respiratory tract problems. It is commonly used to treat many kinds of breathing difficulties, caused by infections, inflammations or allergies, like cough, bronchitis and tuberculosis.

- Digestive tract ailments. Callistemons are commonly used for infections or inflammations of stomach and intestines, that cause abdominal pain or diarrhea.

- Bacterial infections. C. viminalis and C. citrinus are traditionally used to treat many kind of bacterial infections, whether in mouth, lungs, stomach, intestines, urinary tract or skin.
Extracts from leaves of those plants has shown antibacterial activity against : Staphyllococcus aureus, Streptococcus pyogenes, Bacillus cereus, Bacillus subtilis, Baccilus anthracis, Shigella sonnei, Salmonella enteritidis, Escherichia coli, Pseudomonas aeruginosa, Enterobacter cloacae, Streptococcus faecalis, Serratia marcescena, Chromobacterium violaceum, Micrococcus luteus, Salmonella typhi, Proteus vulgaris, Streptococcus pneumoniae, Staphylococcus epidermidis, Klebsilla pneumonia, Klebsiella oxytaci, and many other species of both Gram-positive and Gram-negative bacteria. Those Callistemons are generally compared in its antibacterial effectiveness to standard antibiotics, some studies indicate its esspecially high potential against Gram-positive bacterium.

- Fungal infections. Callistemon viminalis and C. citrinus posses strong antifungal activity, caused mainly by its esssential oil compounds. Many researches in different countries has proved Callistemon activity against wide range of fungi types, from those that are humans or animals pathogens, those that are pathogens of plants, to those that are causing decaying of books. Detailed information on subject of antifungal properties of Callistemons you can read here : - https://shodhganga.inflibnet.ac.in/bitstream/10603/119605/12/12_chapter%204.pdf

- Viral infections. Callistemon tea is traditionally taken as a remedy for flu in Vietnam. C. viminalis essential oil has shown high antiviral activity against Herpes simplex virus 1 (HSV-1) by direct interaction with free virus particles.
The main constituent of essential oils of C. viminalis and C. citrinus - Eucalyptol (on average around 50% of EO), acts on molecular level as inhibitor of COVID-19 virus infection pathway.

- Parasitic worms. Callistemons are traditionally used to treat human worms infections. Essential oil from C. viminalis exhibited anthelmintic activity against tapeworm and hookworm. Aqueous extract of C. citrinus has shown promising results in vivo against Schistosoma mansoni, flatworm that cause schistosomiasis.

- Inflammations. Those two herbs are traditionally used as very effective remedy for many kinds of inflammations, from mentioned here earlier inflammations of lungs, stomach and intestines to arthritis and gout. The methanolic extract from leaves of C. citrinus showed significant anti-inflammatory activity on Carrageenan induced paw edema in rats, comparable with Diclofenac Sodium.

- Urinary track ailments. It is used to treat different kinds of infections and inflammations of urinary system, but also to alleviate children urinary incontinence and bed wetting, and in adult men to reduce a benign enlargement or inflammation of the prostate. Due to its astringent and diuretic properties, it is helpful in relieving water retention and general problems of the urinary tract.
Beside for its oral intake, Callistemon infusion is often used by women as a douche to cleanse the genito-urinary tract from excessive menstruation or a mucosal discharge known as leukorrhea.

- Bleedings. C. viminalis is traditionally used to treat hemorrhoids and bleeding ulcers. Containing a large concentration of silica, it can help to both reduce hemorrhaging and heal the related wound. In addiction it has a hemostatic property related to its astringent function in that it can halt the flow of internal bleeding, such as from ulcers, by constricting blood vessels.

- Pains. Callistemons are traditionally used for pain relieve. Analgesic effect of methanolic extract of C. citrinus leaves was confirmed in tests on mice as significant.

Some researches results also suggests that C. viminalis and C. citrinus can be effective in treatment of : diabetes (both type 1 and 2), high blood pressure, blood clots, liver damage, melanoma, ovarian cancer, or used as a cardioprotective or spasmolytic agent.

Externally smashed Callistemon leaves can be applied as poultice on skin infections, and infusions can be used to wash infected areas.

From many phytochemical researches that have been carried out on Callistemon viminalis and Callistemon citrinus plant material from many different regions of the world. We can clearly see that the both plants chemical profile is almost identical, with differences between chemical composition of both species, not more significant than differences in composition between plants of one of the species taken from different environment. Which validate the claim that both species can be used as its substitutes for health treatments.
The only pattern that can be seen from those data, that distinguish the both species. Is that C. citrinus essential oils generally contain more limonene than essential oils extracted from C. viminalis.

Essential oil is the most important active substance responsible for medicinal properties of Callistemon viminalis and C. citrinus leaves (yield based on fresh weight of mature leaves is 0.1-0.6%). The plants essential oils consists mainly on oxygenated monoterpenes and monoterpenes (61.38% - 94.42%) with less abundant quantity of sesquiterpenes, and are rich in : eucalyptol syn. 1,8-cineole (9%–83%), alpha-pinene, beta-pinene, limonene, alpha-phellandrene and alpha-terpineol (here are some full lists of compounds viminalis and citrinus Egypt , viminalis Punjab India , citrinus Northern India, citrinus Nepal ).
Both Callistemon species leaves also contain : polyphenols (flavonoids - quercetin and kaempferol, tannins, phenolic acids, neolignans - callislignan A and B), triterpenoids (alphitolic acid, lupenol, erythrodiol, taraxerol, betulinic acid, ursolic acid, betulinic acid 3-O-caffeate, morolic acid 3-O-caffeate and ursolic acid 3-O-caffeate), saponins, steroids, phytosterols, alkaloids and flavonol glycosides.

The drug nitisinone that was derived from leptorpermone - originally isolated from Callistemon citrinus and used as herbicide, is nowadays used to treat hereditary tyrosinemia type I.

I didn't found any reports about side effects or contraindications of medicinal use of Callistemons. But due to its high content of eucalyptol, oraly Callistemons leaves infusions or other extracts, should not be taken continuously for long time or in huge doses.

FLOWER REMEDIES

Aborigines in Australia are continuously pouring water for 5 to 10 min. over Callistemon flowers, that drips into container below. As a result they get water sweet from flowers nectar, with unique Callistemon aroma. They have been doing it for centuries. Which means long, long before Edward Bach started to create his Flower Remedies, and his technique of producing the most subtle herbal preparations gained popularity. The Aborigines way of pouring water over flowers hanging on plant stems without picking the flowers, gives way to Stepanovs Method of making Flower Remedies. The so-called Love Remedies differs in this way from classic Bach Flower Remedies, which are made by dipping flowers picked from plants, into bowl of spring water and leaving it in sunny spot.
In their book '' Love Remedies '', Juta Stepanovs with Harald Tietze and Ingfried Hoberd MD write that Callistemon Flower Remedy is suitable for following emotional imbalances : '' stubborn but strong personality; fear of letting go and cleansing; caught in set patterns with a resistance to change (including puberty, parenthood, menopause, midlife crisis old age and death). ''

AROMATHERAPY

I didn't found any information about use of essential oil of any Callistemon species. And instead I found an opinion that C. viminalis EO yield based on fresh weight is 0.1-0.5% (others source is mentioning 0.6%), which makes the yield to be too low for economic use. But in my opinion, even if extraction from material of such a low yield essential oil would cause its high market price, it would be still worth.
Both Callistemon viminalis and Callistemon citrinus fragrances are unique, with main notes of eucalyptuses, citruses and pines, and rich background. These both essential oils are uplifting, invigorating, stimulating but relaxing. It has strong antiseptic and antiinflammatory properties and many other medicinal values (see Medicinal Uses section for details). Therefore it is great for rooms air purification, especially for people with breathing difficulties caused by lungs inflammations, etc. For people which skin is not sensitive for eucalyptol and or other constituents of Callistemons oils, I would also suggest use of it (in dilution) for massage or just topical skin application.
Massage of abdomen can potentially alleviate abdominal pains and maybe even stop diarrhoea. While massages of chest should be helpful for inflammations of respiratory system, and lower abdomen in genito-urinaly systems inflammations.
Topical application can help with many kinds of skin infections, whether bacterial, fungal or viral, and it will also leave the skin smelling nice. It keeps insects away, and there is even possibility that it can repel ticks. As scientific study has showed that C. viminalis essential oil posses strong repellent activity on spider mites, which belongs to the same Acari subclass of Arachnida animals as ticks (Consider all the serious health risks that ticks bites cause, including Lyme disease. I think it is a matter of a great importance to investigate Callistemons essential oils for possible thick repellent properties. And I highly recommend for scientists with means do do such tests).

Since Callistemons essential oils are currently not available commercially. I would suggest for all those that has no apparatus to make their own distillation, simply to make Callistemon leaves infused oil for external use (infused oil for internal, medicinal or culinary use is probably also good idea).
You can also add fresh chopped or dried and crushed Callistemon leaves to your warm bath, or use it to make steam inhalation.

Sources

'' Medicinal Plants in Australia Volume 2: Gums, Resins, Tannin and Essential Oils '' - Cheryll Williams, Rosenberg Publishing 2011

'' Love Remedies '' - Harald W. Tietze, Juta Stepanovs, Ingfried Hoberd MD, Harald Tietze Publishing 2001

PHARMACOGNOSTIC STUDY OF CALLISTEMON CITRINUS L. BARK - SILVIA NETALA, REETHIKA PENMETSA, SNEHITHA NAKKA, BHAGYA LAKSHMI POLISETTY

Triterpenoids and Steroid from the Leaves of Callistemon citrinus (Curtis.) - Farhana Ahmed, Mohammad Sharifur Rahman, Muhammad Abdullah Al-Mansur and Mohammad A. Rashid

FLAVONOIDS AND TRITERPENOIDS FROM CALLISTEMON CITRINUS AND THEIR INHIBITORY EFFECT ON NO PRODUCTION IN LPS-STIMULATED RAW264.7 MACROPHAGES - Nguyen Manh Cuong, Pham Ngoc Khanh, Ho Viet Duc, Tran Thu Huong,

Youn-Chul Kim, Pham Quoc Long, Young Ho Kim

CALLISTEMON CITRINUS (CURTIS.) LEAF SHOWS ANALGESIC AND ANTIDIARRHEAL ACTIVITIES IN SWISS-ALBINO MICE MODEL - Farhana Ahmed, Mohammad Firoz Khan, Sharmin Reza Chowdhury, Mohammad Sharifur Rahman, Md. Al-Faruk and Mohammad A. Rashid

Herbs from Distant Lands

Wednesday, June 24, 2020

Callistemon viminalis and Callistemon citrinus - Weeping Bottlebrush and Lemon Scented Bottlebrush

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