I posted a photo of a plant on Facebook and was pleased with the interest that it aroused among some friends. "What is it?" several asked. "Is it aloe vera? Is it malunggay [maroom in Thai]?"
"It's a kind of cactus," ventured others. "I have this one but the colour is not that variegated and the leaves/stems are thinner -- the old variety."
"It's so beautiful! I've never seen this kind before," two of those who "liked" the plant enthused.
The plant in question is Sansevieria cylindrica 'Patula', a variegated, dwarf variety of the spear sansevieria, a kind of succulent. Cacti are succulents, but not all succulents are cacti. Succulents are plants that are able to store moisture and nutrients in their leaves or stems, which allow them to survive long periods of drought. There are many families of plants that are succulents, among them the cacti family Cactaceae and the agave family Agavaceae, which includes the various species of plants known by their generic name sansevieria.
There are about 70 species of sansevieria, the most common of which is Sansevieria trifasciata, whose long and stiff, sword-like leaves earned it the unkindly name "mother-in-law's tongue". The leaves have variegations which resemble those of a snake, hence it is also known as snake plant. I have known it since I was in grade school as it was planted along our school fence. When I arrived in Bangkok as a young bride in 1969, it was the only plant that thrived under the line of casuarina trees that stood guard in front of my in-laws' compound.
At the time, Sansevieria trifasciata was often taken for granted because it was very common. This changed in the 1990s when a National Aeronautics and Space Administration (Nasa) study discovered that houseplants could purify and revitalise air in sealed test chambers. Sansevieria trifasciata was found to be capable of purifying the air by removing toxins like formaldehyde, xylene and toluene.
Get the point: 'Sansevieria cylindrica' var Patula, a dwarf variety of the spear sansevieria.
According to the book How to Grow Fresh Air by Dr BC Wolverton, formaldehyde is more common in the buildings that we inhabit than we think. It is used to treat many consumer products, including garbage bags, paper towels, facial tissues, fabrics, floor coverings and adhesives.
It is released by gas stoves and found in tobacco smoke. It is also used in building materials such as plywood, particle board and panelling, all commonly used in the manufacturing of home and office furniture and fittings.
Xylene and toluene, meanwhile, are found in adhesives, computer VDU screens, electrophotographic printers, paints, photocopiers, stains and varnishes, and floor and wall coverings.
Following the release of the Nasa findings, Sansevieria trifasciata and its cultivars -- like the S trifasciata 'Laurentii', with leaves edged yellow, and the S trifasciata 'Hahnii', a dwarf, rosette forming variety -- became very popular among the Japanese. Thai nursery owners could not propagate the plants fast enough for export to Japan.
It has been over 20 years since the Nasa findings were released, but sansevierias remain popular -- not just in Japan but also in Korea. Two weeks ago, a Korean plant dealer sent me an email asking for the address of a grower in Ratchaburi from whom he wanted to buy Sansevieria stuckyi. Known in Thai as wan nga chang, Sansevieria stuckyi is grown on farms in Ratchaburi expressly to be exported to Japan and Korea.
Most plants absorb carbon dioxide and release oxygen during the day. Sansevierias do just the opposite: they purify and freshen the air at night while we are asleep. This makes them invaluable as houseplants.
Be it Sansevieria cylindrica, Sansevieria trifasciata or Sansevieria stuckyi and their many cultivars, sansevierias are among the easiest of plants to grow. Rarely attacked by insect pests, they are killed more by tender loving care (overwatering) than neglect. They can be grown in any kind of soil but thrive best in loamy soil with compost in full sun, partial shade or shade. Let the soil dry between waterings.
Sansevierias can be propagated by division or you can take leaf cuttings and root in moist sand and rice husk. The plants multiply so fast that you may have to repot or divide them every year or two.
Email nthongtham@gmail.com.
Long tongue of the mother-in-law: Whether planted in the ground or in a pot, the various cultivars of 'Sansevieria trifasciata' are among the easiest of plants to grow. Photos: Normita Thongtham
