Category Archives: Herbs

All about herbs, medicinal and culinary…

The Magenta Plant

Posted on February 16, 2010 | Leave a comment

Peristrophe roxburghiana is one plant that most older generation Singaporeans would be familiar with. It is a flowering plant that belongs to the Acanthaceae family and is native to southeastern Asia, southern China, and South East Asia. It thrives in the humid lowlands and grows as a lush, herbaceous perennial shrub, up to a height of 0.6 m tall, with lanceoate- to ovoid-acute-shaped leaves.

Unlike many of its more showy ornamental relatives, the true flowers of Peristrophe roxburghiana are not magnificient and they emerge from a small, terminal flower spike. Each flower consists of only two petals which are coloured pink which may appear magenta to reddish-violet to others. There are reports that state there are plants with white flowers.

Despite of the lack of beauty in its blooms, Peristrophe roxburghiana is a plant that is valued as a source of natural food dye. An extract of its leaves imparts a magenta colouring which is used to colour various food desserts in Vietnamese cuisine. The Chinese here knows it via the name ‘红丝线’ (hong si xian) which translates into ‘red silk threads’, with reference to the magenta/reddish dye that is found in its leaves which can be extracted by boiling leaves in water. The leaves of Peristrophe roxburghiana have a sweet taste with cooling properties and are also used medicinally to treat cough, dysentery, diarrhoea and bronchitis. Pregnant women should refrain from consuming this plant.

Peristrophe roxburghiana has a place in any tropical medicinal herb garden. Grow it in a sunny to semi-shaded and well-drained spot with moist, fertile soil. Prune this plant to shape periodically to keep growth in check and ensure a neat and tidy appearance. It propagates easily from stem-cuttings and sections of internodal stem-cuttings and tip-cuttings root easily without any rooting hormone powder. It is relatively pest- and disease-free.

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Introducting the Nipplefruit Plant!

Posted on February 4, 2010 | Leave a comment

Another Solanum species that is a common Chinese New Year festive plant is Solanum mammosum. It is known via a range of common names which include titty fruit, cow’s udder and apple of Sodom and most of these stem from the interesting apperance of its fruits. The fruits of Solanum mammosum is an inverted pear shape where it is broader near the base and narrower near the tip of the fruit. There can be up to 5 protrusions growing near the base of the fruit.

This plant is native to South America and can be found growing in the naturalised state in Central America and the Caribbean. Because of its close relationship with the common eggplant and unique look of its fruit, the Chinese name of Solanum mammosum is known as ‘五角茄’ (wu jiao qie) which translates into ‘five-angled eggplant’. During Chinese New Year, nurserymen and vendors gave it a more auspicious sounding name called ‘五代同堂’ (wu dai tong tang) which translates into ‘five generations living harmoniously under one roof’, referring to togetherness of the family.

As a plant, Solanum mammosum grows as rather untidy, semi-woody, sprawling, perennial shrub which is sometimes grown as an annual. It can grow up to 1.5 m in height and features large, shallowly lobed, furry leaves that come with prominent spikes on both sides. Its branches and stems are also armed with thorns. There seems to be cultivars that are relatively thornless. Flowers are light pinkish purple flowers  and borne in clusters and these develop into fruits which are green at first and turn bright golden yellow when ripe. Fruits are toxic and contain several seeds.

Because of the toxicity of its fruits due to the presence of solanine saponins, Solanum mammosum is mainly grown for ornamental purposes.  The fruits are harvested when they are ripe and sold and displayed while still on the branches for interior decoration and floristry. The plant also has a few medicinal applications such as for the treatment of athlete’s foot, irritability and restlessness. A decoction of the leaves is employed as a remedy for diseases of the kidneys and bladder and to cleanse wounds while the seeds are used as a remedy for colds. The juice of the fruit shows some detergent activity and can be used for washing clothing.

Solanum mammosum prefers to be grown in a sunny, well drained spot. Soil should be kept moist by watering regularly and more often during hot and dry weather. Note that this plant is not too particular about soil requirements and it is most commonly propagated by seeds but  stem-cuttings can be used. Because the toxicity of its fruits as well as the prickly nature of the plant, it is best to grow it in an area that is not accessible by young children.

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The Scrambling Gynura

Posted on January 29, 2010 | 4 Comments

Gynura procumbens is a common medicinal herb that can be seen being grown by home-owners, either in pots by high-rise apartment gardeners or in planter beds by more fortunate gardeners with an outdoor private garden or community garden.

I have only seen in one occasion where there is an English name for this herb, that is, the scrambling gynura, otherwise, it is better known via its Chinese name called ‘jian feng wei’ (尖凤尾, which translates into ‘pointed phoenix tail’) and Indonesian name, daun sambung mjawa. It should not be confused with daun dewa which is another related Gynura species.

In Singapore, Gynura procumbens is believed by the Chinese here to be one that possess the ability to lower blood pressure and sugar levels. Locals here will recommend you to eat 3 – 7 leaves daily in the raw form. I have tasted the leaves before and they have a mild raw taste which makes them quite easy to consume.

To date, there had been a limited number of scientific studies done on on this herb. A Singapore study that used diabetic rat models showed that an alcoholic extract of Gynura procumbens was able to reduce elevated blood cholesterol and triglyceride levels while another by a Korean group of researchers reported that this herb possessed anti-hypertensive properties in a rat model.

Besides the above medicinal properties, according to the Plant Resources of South East Asia (PROSEA), this plant is also used in Africa, where the boiled leaves are applied externally to relieve general body pains and raw leaves for rheumatic pains. Dried and pounded leaves are mixed with oil and applied as a poultice to treat skin compliants. It also used for the treatment of kidney problems and dysentery.

Gynura procumbens is generally regarded to be a relatively harmless herb to consume. In fact, in Java, the young shoots of this plant are eaten raw as a vegetable. Singaporeans may find it more palatable if the leaves have been blanched in hot water before consumption.

This plant grows easily from stem-cuttings. Seeds are not available. It is best grown in well-draining, fertile soil that is kept moist at all times. Semi-shade is preferred by this plant although it can be slowly adapted to grow in full sun, provided the plant does not dry out at the roots. Initial planting under direct sunshine will result in burnt leaves and stunting in growth. Growth should resume once the plant has acclimatised to its new growing conditions.

Gynura procumbens grows as a scrambling perennial plant with stems that can extend to 6 m long if left to grow. The fleshy leaves are bright green that are rather smooth to touch. The shape of leaves can vary depending on the growing conditions and they can range from roundish to ovate in shape but are all shallowly toothed at the margins.

In shade, they are darker green and appear rather flat but under direct sun, the two sides of each leaf may develop a slight V shape along the mid-rib and take on a lighter green colour. The plants I have seen so far have green leaf undersides although I read before that there are plants with purple undersides.

The stems can be totally purple or have patches/specks of purple. From the above description, one can observe that Gynura procumbens can be highly variable. To date, I have not seen flowering specimens before in Singapore.

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First ‘Grow Your Own Western Cooking Herbs’ Workshop @ HortPark

Posted on January 25, 2010 | 1 Comment

A maximum of 30 participants attended the recent gardening workshop entitled ‘Success with Western Cooking Herbs’ that was conducted at HortPark on 23 Jan 2010. It was the first gardening workshop in a series that was crafted to enhance horticulture excellence among Singapore gardeners. Topics covered will be those that will be more relevant to local gardeners. For this workshop, I was surprised by the great turnout and hope that the workshop had been an enjoyable and fruitful experience for all.

I was the instructor of this first workshop and shared with my participants some tricks that will enable them to successfully grow popular Mediterranean culinary herbs in tropical Singapore. With the lack of a local supply of potted culinary herb plants, participants got to learn how they can start their first herb plants from materials bought from the local grocer. Each participant got to bring home a pot of culinary (not commonly available in local nurseries), some pre-mixed soil, herb seeds, rooting powder and a CD containing the workshop presentation slides. Even though 3h was a little long, there is still insufficient to cover such a broad topic. I will work into future workshops more hands-on session.

For those of you who missed this first workshop, do look forward to a second run that is planned to take place in the second half of this year. Gardening enthusiasts can look forward to attend other basic gardening workshops in the series which include basic plant propagation techniques, pest and disease identification and management, high-rise gardening and starting your first outdoor garden.

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A Pretty Mint to Grow – Pineapple Mint

Posted on January 1, 2010 | 1 Comment

For a long time, I wasn’t too interested in culinary herbs like mint. However, via a fellow gardening friend from Green Culture Singapore, my perspective about mint took a dramatic turn and I got hooked to the range of mint cultivars that exist. This is perhaps the first time I am ‘declaring’ my love for this group of edible and very aromatic group of plants.

One of the favourite mints is the pineapple mint. Commonly known via the botanical name Mentha suaveolens ‘Variegata’, pineapple mint features very attractive, oval leaves that are variegated. According to the wonderful book ‘The Encyclopedia of Herbs’ by Tucker and Debaggio, this pretty mint should be botanically named as Mentha suaveolens var. suaveolens.

I got this mint via raising stem-cuttings obtained from material purchased from the supermarket. Fresh stem-cuttings root easily in water. Although called the pineapple mint, the leaves of this mint, when rubbed, do not emit a smell similar in any way to the fruit it was named after. In my opinion, its scent is somewhat sweet and fruity compared to the sharp menthol odour expected from a typical mint plant and this property makes this mint more acceptable to those of us who find the usual mint too strong for the senses. 

The soft, furry and wrinkled leaves of this particular mint cultivar are edged with white or cream which makes it a great garnishing material for desserts and ice-cream. Like most variegated plants, the variegation seen on its leaves depends very much on the light conditions it is grown under. Pineapple mint must not be grown under full sunshine in the tropics as an entire day’s worth of exposure to intense sun’s rays has been observed to burn the leaves. It thrives better if given filtered sunshine for half a day. Sufficient light exposure is still essential to reduce the likelihood of etiolation of stems.

Compared to other mints, the pineapple mint is not one of the easier plants to grow. Besides the light factor, its grower has to know that it is not really suitable for growing outdoors without protection from rain. Rainfall in the tropics can be very heavy and all it takes is one very heavy downpour to flatten a colony of this rather fragile mint. Because of its variegation, the pineapple mint is considerably less vigorous compared to other all green mint cultivars.  Under good light, the stems of this mint can become quite thick and grows upright. Under dimmer conditions, it is seen to take on a sprawling growth habit.

I prune it often to keep the growth of the plant compact and neat. Grow it in well draining soil that is rich in organic matter and kept moist at all times. Remember to feed it often to promote robust growth. Lastly, never allow a mint to dry out!

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What’s Ulam Raja?

Posted on December 30, 2009 | 1 Comment

I first came across a medicinal plant that is called ‘ulam raja’ when I was doing a research project on plant antioxidants during my Food Science and Technology undergraduate days in the National University of Singapore. Thanks for my Malay friend, Hidayat, he was the one who brought me to Geylang Serai wet market on several Sunday mornings to search for vegetables and plants that are consumed by the local Malay community.  I have not seen it being put up for sale in most other markets. In the local market, bundles of fresh, young and tender tips of this plant are put on sale. They wilt quickly, however, under our hot weather here.

Botanically known as Cosmos caudatus, it is sometimes called ‘wild cosmos’ by locals here but it is mostly refered to via its Malay name, ulam raja, which translates into ‘king vegetable’. Native to tropical America, it was first introduced to Philippines via the Spaniards, according to Plant Resources of South East Asia (PROSEA). The pinnate to pinnatipartite leaves of this plant are consumed as a leafy vegetable, usually in the raw form, but sometimes also cooked and mixed with coconut sauce and chillies. It constitutes as one of the more common raw plant leaves eaten a salad-like form, called ‘ulam’ by the local Malay community as well as those in Indonesia and Malaysia.

For the uninitiated, the leaves of ulam raja tastes raw and somewhat astringent. When crushed, the leaves emit an odour that is reminiscent of mango. It is considered as a medicinal herb which is believed to possess the ability to cleanse the blood and strengthen bones due to its high calcium content. From my research, a preliminary one which was done with my then postgraduate colleague, the dried leaves of this plants contain high amounts of potent antioxidants. The results of our work was published in the following paper:

Shui G, Leong LP, Wong SP. (2005) Rapid screening and characterisation of antioxidants of Cosmos caudatus using liquid chromatography coupled with mass spectrometry. J Chromatogr B Analyt Technol Biomed Life Sci. 827(1):127-38.

The plant itself can grow quite tall, up to 3 m tall but is an annual or a short-lived perennial herb. It produces dainty, attractive pink flowers when mature. It should not be confused with the yellow- and orange-flowered Cosmos sulphureus as both species are similar vegetatively and have some vernacular names (randa midang in West Java) in common. The latter are more important as ornamental plants that are a common feature during Chinese New Year.

The ulam raja plant was once difficult to find in Singapore. It can sometimes be found naturalised in abandoned kampongs or wastelands. Occasionally, one is able to find a colony being grown by a Malay resident in a community garden. A few years ago, it was almost impossible to buy pots of this plant. Only recently, I discovered World Farm, a Singaporean wholesale nursery stocking some pots of it for sale to the public. I managed to get some young plants that were weeded out from a colleague’s park a couple of months ago.

This plant is rather easy to grow. It thrives in a sunny spot outdoors with well draining, fertile and moist soil. It is a big drinker and demands a constant supply of food. Under optimal conditions, it grows quickly, flowers and sets seeds very readily. Plants self seed easily and can quickly become a weed in a garden. Harvesting of leaves can commence once plants are 6 weeks old and subsequent ones can be done every 3 weeks. Regular harvesting will stimulate the production of useful and edible foliage and helps to delay flowering.

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The variegated Gardenia – for flowers or leaves?

Posted on November 28, 2009 | 2 Comments

Gardenia jasminoides (also known as Gardenia augusta) is a fragrant flowering  shrub with attractive shiny green leaves and produces fragrant white summer flowers. It is a widely cultivated garden and houseplant and can be grown in pots or outdoors in the ground as a fragrant hedge. Many varieties are now available – there those that are compact and low-growing, flowers are available in both single and double forms, as well as, plants with variegated and non-variegated leaves.

Commonly known as the cape jasmine or garden gardenia, Gardenia jasminoides is a temperate plant that is native to southern China, Japan, Taiwan and possibly also Sri Lanka. In the tropicals, it is reported to do better at altitudes of 400—1200 m. In Singapore’s hot and humid tropical climate, I noticed it prefers to be grown in a semi-shaded location outdoors. Direct sunshine in the tropics is a little too harsh for this shrub. Heat- and water-stressed plants can shed their leaves or their foliage can sometimes taken on an unhealthy yellow colour. 

In the tropical lowlands, this shrub flowers sporadically with a few blossoms each time. It thrives best in fertile and properly drained soil that is near neutral pH value. Do not let the soil dry out and the root zone should be kept moist at all times. Note that the flowers of this shrub are easily damaged by heavy tropical rains and hence it is better to try grow Gardenia jasminoides in a container which can be easily moved around during the rainy season. Interestingly, this shrub tend to flower during the rainy season and that is not surprising, as that is when the weather is much cooler. Bring a potted flowering specimen under shelter to appreciate the flowers so that the flowers don’t get damaged.

When not in flower, the dark leaves of this plant are glossy and makes an ideal foliage plant. This is achievable only when the plant is grown under semi-shade. There is a variegated version and one can see a colony being grown in HortPark’s Floral Walk. The attractive leaves of this cultivar are splashed with random swirls and patches of yellow. Unforunately, I faced much trouble trying to find and admire the flowers produced by the variegated version Gardenia jasminoides. The white flowers do not contrast well with the variegated folige backdrop. 

Not commonly produced here in Singapore, the fruits of the cape jasmine are used in China and Japan for colouring food yellow. Some extracts are commercially available in Japan and they are used to colour boiled beans, fish eggs, hot cakes, liquor, sweets, ices, noodles, candies and imitation crab. The colouring matter in the fruits contains a glycoside, which is identical with the compound called crocetin found in saffron (Crocus sativus L.). The colouring matter is a type of carotenoid pigment. However, more research is needed to prove the harmless character of the dye. The dye is also used to colour textiles yellow or scarlet.

Do you know that the fragrant flowers yield fragrant essential oils and are used in perfumery? In China, they are used for flavouring tea like the common jasmine (Jasminum sambac). Several parts of the plant are used medicinally. The roots are used against headache, dyspepsia, nervous disorders and fever while the leaves are applied in febrifugous poultices. Besides yielding colouring matter, fruits are also used against jaundice and diseases of kidneys and lungs. The seeds contain starch and an oil which is principally composed of palmatic, oleic and linoleic acid.

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Posted in Flowering plants, Herbs, Houseplants, Tropical ornamentals

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The ‘Tomorrow Leaf Plant’

Posted on November 20, 2009 | 19 Comments

Angelica keiskei was once a popular medicinal herb in Singapore. From afar, I think it looks like a enlarged version of the flat leaf parsley plant (Petroselinum neapolitanum). In fact, do not be surprised to know that both plants are members of the Apiaceae (Umbelliferae) family. Common vegetables such as the carrot, celery and dill are also members of this family.

This medicinal herb is often sold singly in pots. It grows as a rosetted plant with a height of about 20 to 30 cm tall. Its large, much divided leaves confers a rather lush look to the entire plant. From my observation, Angelica keiskei seems to prefer to grow in a semi-shaded and sheltered location in Singapore’s hot and humid tropical climate. It doesn’t seem to be able to take our heavy, torrential rains that come down from the skies during certain times of the year here.

Outdoors, try growing Angelica keiskei in a shaded spot that is kept moist at all times. When exposed to excessive direct sunshine, this plant will wilt and turn into a sickly shade of yellow. It needs to be kept moist at all times and hence never allow the soil to dry out. Grow it in moist, fertile soil that is also free-draining.

Angelica keiskei makes a good and attractive houseplant for highrise gardeners. It does well if placed on a bright windowsill that receives filtered or reflected sunshine for at least 4 hours daily. Try to protect it from excessive wind that can dry the plant out.

Recently, I saw some specimens that are in flower on sale in a local nursery for the first time. The much branched flower spike was about 1 m tall and held numerous clusters of small white flowers. Botanically, this particular arrangement of flowers is called an umbel. Some of the flowers have even started to turn into fruits!

Native to East Asia to Japan, Angelica keiskei is known via its Japanese name ‘Ashitaba’. Locally in Singapore, people here call it ‘明日叶’ (ming ri ye) which translates into ”Tomorrow Leaf’, which refers to the ability to regenerate a new leaf soon after one has been harvested. Don’t expect it to put forth a new leaf as soon as the day after! It is not exactly a very fast grower, at least here in Singapore! If you are a fan of this plant, you probably have to have a dozen of pots to satisfy your needs!

The leaves are consumed like a vegetable either in the raw form or cooked by lightly blanching it. When cut, the aerial parts of this plant exude a yellow sap which is found to be an abundant source of furocoumarins and a range of polyphenols. These are believed to possess health-enhancing and anti-cancer properties. However, it is reported that the consumption of Angelica keiskei can lead to skin sensitivity to sunlight and may cause dermatitis in some individuals. Like many members of the Apiaceae family, Angelica keiskei also features a tap root underground that is short and thick. It is also edible and is served either in the cooked or pickled form.

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Allium fistulosum

Posted on September 23, 2009 | 2 Comments

My first encounter with this particular Allium species was when I started my community garden in Serangoon North. One of my community gardeners brought it down from home and planted it in one of the planting beds there. She told us it was from China where she cut and used its foliage like spring onion leaves. Unlike the normal spring onion, its leaves are bluish green in colour and have a powdery bloom on them. They stand erect and continues to grow vigorously throughout the year in Singapore. It is vital to grow this plant in direct sunshine, otherwise, the leaves will tend to flop all over.

That was about three years ago and at that time, this Allium species was still not available in the market. It was only in the recent few months did I start to see pots of it appearing in our local nurseries. Most of the time, pots of the plants that are available for sale are not in bloom. There was only one occasion that I managed to purchase a pot that was in flower.

Botanically known as Allium fistulosum, this Allium species has various common names which range from Japanese bunching onion, Welsh onion, multiplier onion and scallion. It is widely grown in tropical Asia and does not develop bulbs like the common onion. It produces basal lateral buds which develop into many offshoots and hence the common name ‘bunching onion’. Flowers are produced in a spherical umbel on a hollow scape and they open from the tip of the umbel downwards.

Plants that appeared in the local nursery scene seem to be rather heat-tolerant since there are sources that report that Allium fistulosum does not thrive in lowland areas with temperatures greater that 25 deg C. This Allium species appear to be also able to tolerate the high rainfall encountered in Singapore as long as it is grown in well-draining, fertile soil that is also rich in organic matter.

I came across a source which mentioned that some Allium fistulosum cultivars flower in short daylength but in general, these conditions encourage vegetative than reproductive growth. Assuming all nursery stock on sale are at the same stage of growth, this could probably mean that there are several different (but indistinguishable) cultivars that are available for sale in Singapore, which explains why some batches of this Allium species do flower whereas others only produce leaves and never flower?

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The Elephant Vine

Posted on July 25, 2009 | 1 Comment

Argyreia nervosa, referred to via a range of common names including elephant climber, elephant creeper, elephant vine and silver morning glory, is a member of the Convolvulaceae (morning glory) family. Native to India and Burma, it was once a popular landscaping candidate in Singapore.

This perennial vine is particularly valued for its rapid growth rate and large size that it can grow into. The young shoots of this plant can extend several centimeters daily and the plant can grow up to 15 m long. Hence, Argyreia nervosa is often used to quickly cover up an area, such as a trellis or a long series of railings of a boardwalk. The visitor to the coolhouse at the National Orchid Garden in Singapore would have noticed this plant.

Argyreia nervosa is a distinctively furry plant. Its mature leaves are heart-shaped and have a light velvety feel. New growth of this vine is densely covered with fine, silver hairs that it appears as if they have been silver-plated. It is no wonder that it is a plant that is featured in HortPark’s (Singapore’s gardening hub) Silver Garden.

A friend shared with me that one can actually pick a young leaf still adorned with its silvery coat and press it between the pages of a thick book. The silver colour of the leaf will be preserved and can be laminated with a piece of cardboard to make a nice bookmark or greeting card.

Argyreia nervosa is reported to be very well adapted to a dry tropical climate such as areas near rivers and creeks but with a distinct wet and dry season. It is not naturally found in the wet, humid tropics. The silvery hairs found on the new growth is perhaps an adaptive mechanism that the plant has evolved to reduce water loss in such a climate.

This vine also produces pretty flowers at the vine tips. Hence it is advisable to not frequently cut back the growth of this plant if one desires to see its flowers. Each flower is shaped like a trumpet and resembles those produced by the common morning glory. When in flower, the blossoms add interest by punctuating the largely green background of leaves with lavender.

Besides ornamental value, Argyreia nervosa possesses medicinal properties. The roots of this flowering vine are traditionally used to treat rheumatism and arthritis whereas its leaves are applied to wounds and abscesses. Its seeds possess psychedelic effects.

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Posted in Flowering plants, Herbs, Tropical ornamentals