Monthly Archives: July 2009

Root Awakening (11 July 09)

Posted on July 11, 2009 | Leave a comment

The second instalment of the Root Awakening column for month of July 09 provided answers to three gardening questions. The first question was about the growing of petunias. Petunias are herbaceous members of the Solanaceae family. They are usually treated as annuals where they are usually discarded after flowering because plants tend to become straggly and lose their vigour after some time. They are direct sun-lovers and need to be watered and fertilised regularly during the active growing and flowering period.

The question enquired on the successful growing of bougainvilleas. These woody shrubs are very popular flowering plants for a long time. Plants can be grown inside large containers of soil indefinitely as long as they are well-fertilised and the gardener has to ensure that the soil is well aerated after some time as soil tends to compact over time. Compacted soil devoids the plant of root growth space and air, and makes penetration of water difficult. Bougainvilleas are also sun-lovers and need to be grown under direct sunshine.

The last question asked how one can grow his/her own hydroculture plant. There are ready kits that can be bought from the local nursery. The most famous is perhaps the Luwasa hydroculture system. To grow plants using this system, it is best to start new plants from cuttings in hydroculture or buy plants already established and adapted to the hydroculture growing environment. Transplanting a soil-grown plant and washing its roots can be a traumatic experience for some plants and not all will take such an operation well.

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The Beautiful Persian Shield

Posted on July 9, 2009 | Leave a comment

The Persian shield is a magnificent foliage shrub that appears to be a relatively new introduction to the landscapes of Singapore. Still not widely planted, this plant is only available for sale in a few nurseries in Singapore and remains a plant collector’s item . I remember having seen this plant featured on some houseplant books published overseas eons ago.

A native of Myanmar, the Persian shield is an evergreen plant with non-woody stems that can grow up to 1.2 m tall with a slightly smaller spread. Its stems are square in cross-section which are characteristic of plants belonging to the Acanthaceae family. The leaves of the Persian shield are oval in shape with a sharp tip and occur on opposite sides of a stem. They have an interesting texture and admired mostly for their beautiful variegation.

Depending on the prevailing light conditions, its leaves usually have two broad, silvery-metallic purplish-pink bands that run along the length on opposites of the mid-rib, which shimmer with iridescence. The undersides of the leaves are purple in colour.  Although I  have not seen it in flower, the blossoms of the Persian shield are said to be funnel-shaped, pale violet that are produced on short, erect spikes.

Persian shield is one of the few foliage shrubs that do well under semi-shade. It can be grown as a colony as a focal plant or as a border plant around a planted bed. With such light requirements, I foresee that the Persian shield can also be grown in an apartment where one can place it at a bright location such as a balcony or corridor where it can receive filtered sunshine for at least half a day.  

Because it is a semi-herbaceous plant, the Persian shield, in general, is not drought-tolerant and should be watered to keep the soil moist at all times. It should not be allowed to dry out. Feed with a balanced fertiliser and prune back the plant periodically to ensure a compact and bushy growth habit. Plants can becoming unkempt-looking and straggly if allowed to grow unchecked. It is easily propagated via stem-cuttings.

Botanically known as Strobilanthes dyerianus, it is a member of the Acanthaceae family. The genus name of this plant, Strobilanthes, is derived from two Latin words, ‘strobilos’ and ‘anthos’, which have the meanings of ‘cone’ and ‘flower’ or ‘shoot’, respectively. Its specific epithet dyerianus  is given in honour of Sir William Turner Thieselton-Dyer, a professor of botany at the Royal Colleage of Science and director of the Kew Gardens.

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The Zingiberaceae Talk @ Singapore Botanic Gardens

Posted on July 7, 2009 | Leave a comment

Last Saturday at the Botany Centre’s Function Hall, I gave a talk on the family of true gingers – Zingiberaceae – as part of the Community in Bloom gardening talk series. It was a sequel to an earlier one that covered on the Zingiberales order, which was delivered on 14 Mar 09. The latter was a bold attempt to introduce to the public a huge order of plants consisting of 8 families of flowering plants which are monocotyledons. 

The Zingiberaceae is a family that consists of numerous herbaceous plants that have important economical, ornamental, medicinal and culinary uses. Many Singaporeans grow members of the true ginger family in their gardens, be it private or a community garden.

True gingers which are distinct from spiral gingers which are classified in a family of their own, Costaceae. Spiral gingers are popular ornamental tropical plants that are used quite prevalently in landscapes here in Singapore. There are two rather obvious differences between the plants from these two families.

True gingers emit an aromatic smell when a part of a plant is bruised whereas spiral gingers do not emit any smell. Spiral gingers, as their common name suggests, adopt an interesting growth habit where their leaves on a stem are arranged in a spiral manner. The leaves on a true ginger are produced distichously with respect to the leafy shoot (pseudostem).

I started my talk with gingers that most people are familiar with. Starting from the culinary gingers that are used in everyday cooking such as, Zingiber officinale (common ginger) and Alpinia galanga (greater galangal), my audience were brought on a discovery journey that gradually transit into the realm of ornamental gingers. In the talk, I took the opportunity to highlight some of the prettier and interesting ones such as Hedychium coronarium, also known as butterfly ginger that produces fragrant butterfly-shaped white flowers. The stunning Etlingera elatior or Torch Ginger, a towering and majestic plant with immense ornamental value, which also produces edible flower buds, was not forgotten.

After an introduction to a selection of various true ginger species that are worth growing, I shared with those present on how to grow them and solutions to problems that are commonly encountered during cultivation. A rather lively and interactive question-and-answer session then took place which lasted for about 45 mins. It was hoped that everyone benefited from the talk and sharing session.

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Root Awakening (4 Jul 09)

Posted on July 5, 2009 | Leave a comment

 The first instalment of the Root Awakening column for the month of July 09 was published yesterday. As usual, answers were provided for three gardening questions sent in by the readers of Straits Times Life! 

One of the first questions revolves around the growing of fruit trees. This time, its about the rambutan. A reader asked why his/her rambutan tree fruits tend to fall off prematurely. Rambutans need a prolonged dry season to trigger flowering but they need to be well-irrigated to reduce the likelihood of water stress that will lead to premature abortion of young fruits.When a tree has started to produce fruit, remember to provide water to the tree. A ring of well-rotted compost can be added and bone meal supplementation can help to boost fruiting. 

The second question asked why the leaves of the pomegranate dried up. The symptom  described can be due to a number of causes. The plant may be grown in an overly windy condition. Young leaves can dry up as a result of strong, perpetual winds. Leaves could also dry up due to mite infestation. Mites can cause leaves to roll up and become distorted which eventually dry up. Cut away affected parts and spray with white summer oil to control mite population. It could also be due to insufficient light as pomegranate is a shrub that requires at least 6 hours of direct sunshine to grow. Overwatering may be a reason as well. Soil for growing pomegranate needs to be kept moist and not wet. Let soil dry out a little before watering again.

The last question enquired whether can subtropical fruits like avocados and lemons be grown in tropical Singapore. These trees can be grown in Singapore as they thrive and attain best quality in summers where there are longer daylight. It is best to buy ready plants that are known to produce in lowland tropical climates from local or overseas nurseries. Lemon can be grown in pots but fruits may not turn yellow when grown here.

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Home Concepts Magazine (Jul 09 issue)

Posted on July 3, 2009 | Leave a comment

In the July 09 issue of the Home Concepts magazine, I penned an article entitled ‘Spice of Life’ for the regular Garden Treats column. In it, I introduced five common trees that are sources of culinary spices. Spices is a term that is used to refer to dried plant parts that are used in small quantities to flavour the food we enjoy. Some of them also possess medicinal uses. On the other hand, the word ‘herbs’ is used to call entire plants or parts of a plant used in the fresh form for flavouring food. Both terms are used interchangably and have caused much confusion.

Depending on what are the spices, they can be derived from bark, leaves, flower buds, fruits, aril and rhizomes of plants. In my article, I introduced five common culinary spices and the reader can expect to see excellent pictures depicting the five spices, together with their leaves and fruits (where applicable)!

One of the first spices that was mentioned is the candlenut (Aleurites moluccanus, Euphorbiaceae). The part of plant used for flavouring purposes is the seed kernel of the candlenut fruit.

Another common spice, cinnamon, which is available in quills are derived from the bark of trees belonging to the genus Cinnamomum. Cinnamomum verum yields the true cinnamon whereas C. aromaticum is the source of Chinese cassia, which is often used to make the five spice powder. Both trees are members of the Lauraceae.

Clove is derived from the unopened flower buds of the tree, Szygnium aromaticum, a member of the Myrtaceae family. Common tropical fruits such as the jambu and guava are classified in the same family.

Mace & nutmeg come from the same tree, Myristica fragrans (Myristicaceae) and tamarind is derived from the fruits of Tamarindus indica, which is a member of the bean family, Fabaceae.

These five spices are derived from various tropical tree species which are well at home in the tropics. In Singapore, some of them are grown in our public parks or planted along our roads. To see some them all at once, pay a visit to the herb and spice gardens at Fort Canning Park and Singapore Botanic Gardens. Both green spaces have numerous mature trees and if one is there at the right time, he/she can see the trees in flower or producing fruit.

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Geophytes Showcase @ HortPark

Posted on July 1, 2009 | Leave a comment

Last Saturday, I was involved in giving a guided tour at the Lifestyle Corner at HortPark. The tour and showcase were aimed at educating the public what geophytes are and various common vegetables and medicinal plants that belong to this category of plants. The showcase is now on until 27 Aug 09. It will run through GardenTech 2009 (14 to 18 Aug 09 @ HortPark) and visitors to this garden fair will also get a glimpse into how one can use geophytic plant parts for home decoration!

In brief, a geophyte is a herbaceous plant with an underground storage organ. Storage organs are reservoirs of carbohydrates, nutrients and water and play an important role in the plant’s survival during adverse climatic conditions and we, humans farm them for food and medicine.

Do you know how to differentiate a taproot, tuber, rhizome, bulb or corm? These are terms that are used to describe underground vegetables such as carrots, potatoes, gingers, cocoyams and onions, respectively.

A root tuber is a modified lateral root that stores food for the plant. Either the tip, part of or the whole lateral root swells up to become a storage organ. Root tubers have the internal and external cell and tissue structures of a typical root. Unlike stem tubers, root tubers do not have nodes. Common root tubers are cassava (Manihot esculenta) and sweet potato (Ipomoea batatas).

A stem tuber is a swollen, modified underground stem that stores food for the plant. Internally, a stem tuber has the typical cell structures of a stem, including a pith, vascular zones and a cortex. Common stem tubers include the potato (Solanum tuberosum) and Chinese yam (Dioscorea opposita).

A bulb is a vertical, underground stem consisting of a compressed stem (basal plate) and modified scale-like leaves. These modified leaves serve as the primary storage tissue. Bulbs are divided into tunicate and imbricate bulbs. A tunicate bulb such as onion (Allium cepa) and garlic (A. sativum) have a paper-like covering, or tunic, that protects the scales from drying and mechanical injury. A common imbricate bulb is the edible lily bulb (Lilium sp.) which is often an additive in Chinese herbal desserts.

A corm is a vertical, underground stem that serves as a storage organ with one or more internodes. It is encased in dry, papery, dead petiole sheaths which act as a covering that protects the corm from insect attack and water loss. Corms have internal solid tissues. This distinguishes them from bulbs, which are made up mostly of layered fleshy modified leaf scales. Common corms include the cocoyam (Colocasia esculenta) and water chestnut (Eleocharis dulcis).

A taproot is a swollen, tapering root that grows vertically downwards. Lateral, fibrous roots grow out from this main taproot. Many taproots are also modified to become storage organs. Taproots can be divided into 3 main cateogries: conical root – carrot (Daucus carota), fusiform root – radish (Raphanus sativa) and napiform root – yam bean (Pacchyrhizus erosus).

A rhizome is a swollen horizontal stem of a plant. It is usually found underground, often sending out roots and leafy shoots from its nodes. A rhizome is a modified stem, and the stem tissue itself serves as the primary storage tissue. A common rhizome is the cooking ginger (Zingiber officinale).

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