Root Awakening

Mango sapling
Mango saplingPHOTO: B.T. CHEE
Chinese violet (Asystasia gangetica)
Chinese violet (Asystasia gangetica)PHOTO: TAI HUI HUANG
Orchid
OrchidPHOTO: JANICE TAN
Noni plant (Morinda citrifolia)
Noni plant (Morinda citrifolia)PHOTO: ANG YIT BENG

Damaged mango sapling may pose issues if allowed to grow

It has taken almost three years to grow this mango tree from a seed. However, a large chunk of the main trunk has been torn by a passing truck. Is it possible to salvage the tree? Will it recover if I remove the existing branch and cut it off right at the bottom end where the trunk is torn? Or do I wait for shoots to regrow from the damaged area before pruning the existing branch?

B.T. Chee

Your mango sapling is so damaged that if you allow it to grow, there will be subsequent arboricultural issues. The tear will not heal properly and can lead to disease and structural integrity issues.

You can prune the sapling below the damaged portion. New shoots will usually be produced and one of these can then be used for further growth.

It is advisable to engage the professional services of a certified arborist on proper and safe tree management.

It is also not advisable to plant a mango tree at the current site because it can grow rather large with time. The limited root space is not conducive for the growth of the tree in the long term. Roots may damage the concrete kerb and pathway, and exposed roots can become a tripping hazard.

Finally, low branches of the tree will hinder movement of vehicular traffic on the road next to it.


Chinese violet is a common ornamental groundcover plant

This plant grows best when it has a support. What is its name? Also, after consuming it, I find that it aids my bowel movement.

Tai Hui Huang

The plant is commonly known as the Chinese violet (Asystasia gangetica). The large-flower variety shown is often grown as an ornamental groundcover plant in gardens.

It grows easily from stem-cuttings and prefers a sunny location with moist, well-drained and fertile soil.

Its tender leaves and stems are documented to be eaten as a vegetable, stir-fried or boiled.

However, the plant's medicinal properties are largely anecdotal and not well-studied. It is not advisable to self-medicate without guidance from a medical practitioner.


Orchid is dehydrated

My orchid had some yellow flowers, but after those withered, the plant is not growing well now. What should I do?

Janice Tan

Your plant is likely a cultivar of the Dancing-lady orchid (the Golden Shower variety of the Oncidium Goldiana or related hybrid).

From the shrivelled pseudobulbs, it appears that your plant is severely dehydrated.

Depending on your growing conditions, you need to water at least once a day to ensure the plant gets sufficient water. It requires more frequent watering if the area it is grown in is windy or sunny.

Ensure that the size of the charcoal chips is appropriate. Overly large chunks of charcoal will dry out quickly. Very small chips will retain water and not dry out. If the roots are kept moist for too long, they will die away.

Check the health of the roots: Healthy roots should be white and firm. Dead roots will not function and water uptake will be affected.

If the roots are dead, you need to prune them and pot the plant in fresh charcoal chips of a suitable size.

Also, ensure your orchid receives sufficient sunlight for healthy growth. It should be situated in a location where it can get at least four hours of filtered sunlight.

It should not be grown under direct sunlight as intense sunlight will bleach or burn the leaves.


Noni plant grows readily from seeds dispersed by animals

This plant is growing wild outside my house. Is it a noni?

Ang Yit Beng

The plant is indeed the noni (Morinda citrifolia). The seeds of this plant are dispersed by birds, rats, bats and other animals that consumed its ripe fruit.

It is common to see this plant growing in the most unexpected places in urban areas and wastelands.

Ripe noni fruit smells like putrid cheese. It is edible and believed to have health benefits. The leaves, called Daun Mengkudu, are also eaten raw and are sold in the Geylang Serai market.

•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.

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

A version of this article appeared in the print edition of The Straits Times on December 29, 2018, with the headline 'Root Awakening'. Print Edition | Subscribe