Root Awakening

Plant is not limau purut, but possibly Common Lime
Plant is not limau purut, but possibly Common Lime.PHOTO: LI REN HSU
Burnt leaf edges could be caused by excessive fertilisers or a disease
Burnt leaf edges could be caused by excessive fertilisers or a disease.PHOTO: CATHERINE GOH
Distorted young chilli leaves may be due to a broad mite infestation.
Distorted young chilli leaves may be due to a broad mite infestation.PHOTO: PAIGE LOH
Creeping Charlie.
Creeping Charlie.PHOTO: CHU JIN JY
Weeping Willow.
Weeping Willow.PHOTO: SERINE GOH

Plant is not limau purut, but possibly Common Lime

This plant grows well in my balcony garden. Is it another version of limau purut? Can the leaves be cooked in curry and eaten?

Li Ren Hsu

The plant is not the limau purut (botanical name: Citrus hystrix). The limau purut plant, also known as the Kaffir Lime, has rather distinctive leaves. Each leaf consists of two roughly similar-sized lobes connected together, forming a figure "8".

Your plant could be another citrus species, possibly the Common Lime (botanical name: Citrus aurantifolia). To ascertain its identity, the shrub has to be allowed to flower and fruit. The plant is better known for its fruit whose juice is extracted and used to flavour dishes.

Burnt leaf edges could be caused by excessive fertilisers or a disease

Why are the leaves of my plants browning at the edges?

Catherine Goh

The plants appear to be the hydrangea (botanical name: Hydrangea macrophylla). Two reasons could have caused the edges of the leaves to turn brown.

Do you fertilise your plants frequently? Any fertiliser that is not taken up by the plants can accumulate in the soil over time and excessive salt concentrations from unabsorbed nutrients can show up as burnt leaf edges.

The only way to resolve this is to stop fertilising the plants for a period of time and to flush the soil with water to wash out excess fertiliser salts.

Another possibility is an infection by pathogenic fungus or bacteria. Ensure your plants are given ample space to grow. Avoid crowding them too much as this will reduce air circulation, which may then lead to disease.

If this is the cause, it is recommended you space the plants out to improve the movement of air and allow the leaves to be exposed to some sunlight.

Ensuring that there are better growing conditions for the plants should improve the situation.

Distorted young chilli leaves may be due to a broad mite infestation

My chilli plant seems to look healthy and is growing well. However, I noticed that some leaves have curled up. The plant was previously infested with mealy bugs, but I managed to get rid of them and pruned the affected leaves. Is it infected by other pests?

Paige Loh

Your chilli plant (botanical name: Capsicum species) may be infested with a pest called broad mites.

Broad mites are not visible to the naked eye and need to be viewed under a microscope to be seen. They suck sap from young, developing leaves and cause them to become distorted or deformed. In serious cases, the growing tips of plants die and plants become stunted.

Broad mites can be treated using micronised sulphur-containing substances such as lime sulphur solution or sulphur soap. The application of either substance needs to be focused on the young, developing foliage and growing tips of plants. Regular treatment can help to suppress the population of broad mites.

Attractive groundcover plant is known as the Creeping Charlie

What is the name of this plant? Does it have any medicinal purpose?

Chu Jin Jy

The plant is commonly called the Creeping Charlie and its botanical name is Pilea nummulariifolia.

It is commonly mistaken to be the edible mint, due to its growth habit and appearance of its leaves. However, the two plants are not related.

This plant is grown more as an ornamental plant - its sprawling growth habit makes it an ideal candidate for groundcover or as a draping plant, where its long stems are allowed to cascade over hanging baskets and planter boxes. It can be grown in semi-shaded areas and its soil should be kept moist at all times.

Weeping Willow lookalike is Weeping Tea-Tree

What tree is this? Is it a willow tree?

Serine Goh

The tree is botanically known as Leptospermum madidum ssp. sativum and its common name is Weeping Tea-Tree.

Although its appearance resembles the Weeping Willow Tree (botanical name: Salix babylonica), the two are not related.

The narrow leaves of this tree emit an aromatic scent when crushed, due to the presence of an essential oil. The tree has a unique feature where its bark peels away in thin strips, exposing a brownish-pink inner bark that ages to creamy white upon exposure to air.

The Weeping Tea-Tree is often preferred for growing in Singapore as it is not susceptible to attack by the caterpillars of the Leopard butterfly.

• Answers by Dr Wilson Wong, an NParks-certified practising horticulturist and park manager. He is the founder of Green Culture Singapore and an adjunct assistant professor (Food Science & Technology) at the National University of Singapore.

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A version of this article appeared in the print edition of The Straits Times on June 15, 2019, with the headline 'Root Awakening'. Print Edition | Subscribe