Root awakening: Gunpowder plant suitable for miniature gardens

Candle Bush a popular medicinal plant.
Candle Bush a popular medicinal plant.PHOTO: YEOW CHENG GEOK
Gunpowderplant suitable for miniature gardens.
Gunpowderplant suitable for miniature gardens.PHOTO: LAURA AU
Mealybugs cause of white substance.
Mealybugs cause of white substance.PHOTO: FLORENCE WEE
Sterilise soil before reuse.
Sterilise soil before reuse.PHOTO: SEE SOO ENG
Dragon’s Tongue.
Dragon’s Tongue.PHOTO: WILSON WONG

Gunpowder plant suitable for miniature gardens

I found this plant growing in one of my pots in the balcony and decided to keep it. What is it and is it safe to grow it?

Laura Au

It is botanically known as Pilea microphylla.

Its common names include artillery plant and gunpowder plant and it is a member of the Nettle family (Urticaceae).

This plant, which is not a true fern, often occurs as a weed in planted areas. It is usual to find it sprouting from a pot of soil left from an earlier potted plant.

Under ideal conditions, the plant will self-seed and can become a nuisance if it grows in areas where it is not wanted.

Due to its small leaves and stature, it can be used creatively for planting miniature gardens.


Candle Bush a popular medicinal plant

At the Botanic Gardens, I took a photograph of this plant, which was beside a pond. What is it?

Yeow Cheng Geok

It is the Senna alata and is a member of the bean family (Fabaceae). Its common names include Seven Golden Candlesticks and Candle Bush, which refer to the upright inflorescences with numerous yellow flowers that the plant produces.

It grows best in sunny areas and tolerates wet feet. The leaves are also food for caterpillars of the Mottled Emigrant butterfly.

It is a popular medicinal plant. The ground leaves of the plant are used to treat fungal infections such as ringworm.

Use its botanical and common names to search for information on it on the Internet. There is also published literature on its medicinal use.

At the Botanic Gardens, you can find out about a plant's botanical and common names on the label, which is often located in front of the plant.


Mealy bugs cause of white substance

What is this sticky white substance on my plant? How do I get rid of it?

Florence Wee

The plant is a Gardenia. The most common Gardenia sold in nurseries here is Gardenia jasminoides, which is commonly known simply as Gardenia or the Cape Jasmine.

Your plant appears to be infected by mealy bugs - insects that suck sap from it.

If it is a minor infestation, take the plant to the bathroom and use a strong jet of water to wash the pests off. This is the most environmentally safe method.

If the infestation is severe, try organic pesticides such as neem oil or summer oil. For persistent infestations, you may want to use chemical pesticides such as cypermethrin.

When applying pesticides, cover the plant thoroughly, including the growing tips of the plant, undersides of leaves and tight areas between the leaf stalks and stems.

It is necessary to repeat applications at least weekly to bring the infestation to a manageable level. You may also need to switch your pesticides to avoid the development of pesticide resistance in pests.

Wear appropriate protective gear during application and keep young children and pets away.

Plants are often affected by pests when they are stressed. In many apartment gardens, the most common stresses are caused by insufficient sunlight and overly dry air from constant wind.

Having a good understanding of your growing environment and putting in the right plants can help reduce many common pest and disease problems.


Sterilise soil before reuse

I am removing this plant and reusing the pot for new plants. The previous plant had white, cotton-like powder under its leaves and a black film all over it. Is it safe to reuse the soil?

See Soo Eng

Your plant is likely to be infected by mealy bugs, which are insects that appear as white cottony masses where they suck sap from the plant.

You can use a strong jet of water to wash the pests off; organic pesticides, such as neem oil or summer oil; or chemical pesticides such as cypermethrin to treat the problem.

The black film is likely to be sooty mould. It is a fungus that does not really harm the plant, but is an eyesore. In very severe cases, it can reduce plant vigour by preventing photosynthesis.

More importantly, the appearance of sooty mould often points to an existing sucking insect infestation, most likely due to the presence of mealy bugs.

Sucking insects often excrete a sugary substance which is deposited on leaves and leads to sooty mould. You need to manage the population of mealy bugs to reduce the further spread of sooty mould.

You can gently wipe off sooty mould with lukewarm water. Avoid using strong soaps or detergents as these can damage the foliage of the plant.

Soil can be reused, as long as it is sterilised to get rid of critters. This can be done by pouring hot water over the soil and allowing the soil to cool and dry before using it again.


Tip: Dragon's Tongue is a silver star

Commonly known as the Dragon's Tongue ("long li ye" in Chinese), this plant is better known locally as a medicinal herb and is used to treat respiratory tract ailments such as coughs. Its botanical name is Sauropus spatulifolius and it is a relative of the common leafy vegetable, cekur manis.

You can grow it in an ornamental garden as its elongated green leaves have a beautiful silver pattern that spreads out from the leaf veins, making it an ideal candidate for a silver-themed garden.

The leaves are best shown when the plant is grown under bright indirect sunlight. Intense sunlight will bleach the pattern.

It is a valuable landscaping candidate as most silver-leafed plants are full sun plants. Create visual texture with the plant's broad leaves by introducing something with finer leaves, such as the Aluminium Plant (Pilea glaucophylla), as shown.

In the landscape, you can use it as a ground cover for a moist and shaded area. Young plants are small in stature and as this plant's growth rate is slow, it does not require frequent pruning.

•Answers by Dr Wilson Wong, a certified practising horticulturist and founder of Green Culture Singapore (www. greenculturesg.com). He is also an NParks-certified park manager.

•Got a gardening query? E-mail it with clear, high-resolution pictures, if any, of at least 1MB and your full name to stlife@sph.com.sg.

A version of this article appeared in the print edition of The Straits Times on November 14, 2015, with the headline 'Root awakening: Gunpowder plant suitable for miniature gardens'. Print Edition | Subscribe