At the risk of boring you, dear reader, let me briefly explain more fully. Plants give off water through their pores (or stomata) in an evaporative procedure known as transpiration. This process is necessary for a range of very different reasons: to draw up nutrients from the soil in solution; to promote photosynthesis, a process absolutely vital to our continued existence on the planet, whereby the leaves convert carbon dioxide in the air to organic compounds; and finally and simply to cool the leaf in hot conditions.
It is estimated that at a temperature of 30 degrees – normal in Thailand – leaves lose water three times faster than at 20 degrees. So all plants, except those that naturally enjoy dim light and constant humidity under the rainforest canopy, need to have adaptable leaves that can reduce water loss by closing or contracting their pores.
But extreme conditions in the tropics do not just mean high temperatures. As we all know, Phuket experiences torrential rain in the monsoon – up to 300 centimetres of the stuff. So plants have to be adaptable in other ways, namely to have the capacity to shed water rapidly from their leaves, so that the branches don’t hang heavy and break.
Thus it is that some leaves are deeply grooved and veined to allow runoff, others have oily, leathery or shiny surfaces and a few have small pointed leaves that droop. As a result, there is huge diversity in leaf shape, size and colour. Little wonder, then, that many of these plants are cultivated for their foliage alone. And why not?
Note that I am not talking about foliage that actually mimics flowers – the multi-coloured bracts of the bougainvillea for instance, or the yellow or red of the poinsettia (kistmas in Thai for obvious reasons). Nor is this the occasion to consider the many varieties of palm that are grown for their attractive fronds, though I will mention in passing the golden cane palm, the sealing wax palm, the traveller tree and the ruffled fan palm as species that are all well worth cultivating – if you have the room in your garden. No, the following recommendations are about plants possessed of foliage that looks like foliage, leaves that look like leaves, albeit in fascinating colours.
Acalypha wilkesiana (huu krataai)
One of my favourites is acalypha wilkesiana. It has a string of common names – Jacob’s coat, Fijian fire plant or painted copperleaf – all of which accurately describe its handsome appearance. It grows naturally in Vanuatu. I like it because it is a strong, erect evergreen with a closely arranged crown, will put up with shade or sunshine provided its roots have water and, most important of all, produces a dense show of large, variegated leaves that range in hue from coppery red to shades of green and yellow.
That it is often used here in sheared hedges speaks volumes for its durability. The only concern is its proneness to attacks from mealybugs. Propagate from stem cuttings.
Graptophyllum pictum (bai ngoen)
Another useful shrub is the absurdly named caricature plant (graptophyllum pictum), for which camouflage plant might be a better name on account of its colourfully blotched leaves in yellow and vivid green, sometimes suffused with reddish pink. Its livery reminds me of the combat gear one sees so many young people wearing around the place.
This erect shrub, which hails from New Guinea, grows to two metres or so, and will tolerate sun or partial shade. Both of these shrubs, mostly propagated from cuttings, are residents in my garden where they provide variety and colour when other plants are not in bloom. That is always one of the chief merits of a good foliage plant.
Codiaeum variegatum (croton)
My other top choice is the croton (codiaeum variegatum), a plant that grows everywhere in the tropics. I have seen mature specimens in Thai forecourts that are 10 feet tall, but usually they are much smaller and appear in rows, in formal arrangements or in pots.
The croton will be familiar to most Europeans as the most ubiquitous of all house plants, its showy, leathery and deeply veined leaves arranged around a central stalk. There are many cultivars and many colours; the foliage on one specimen can be anything from deep green through yellow to orange and red – hence its Latin tag of variegatum.
It is, in its natural jungle habitat, one of the understory plants, preferring moist conditions, and capable of existing beneath the forest canopy. Thus it should not be planted in unremitting sunshine. If it gets overheated or dry, it will let you know by shedding its lower leaves. But it does well in the spaces between larger shrubs.
Cordyline terminalis (mak phuu mak mia)
So too the cordylines, a large genus of single-stemmed, perennial herbs which dislike full sun even more, and which, for this reason, were once fashionable as container plants in English drawing rooms. Most commonly cultivated is the marginata variety with glossy, sword-like leaves of a distinctive deep purple or greenish violet colour. Some recent hybrids such as terminalis are a brilliant crimson; the light shining through their translucent foliage gives the leaves a luminous glow.
It grows quickly in ideal conditions – I have one in a shady border which is already two metres tall. Moreover, the vivid colouration makes it a popular contrast plant in any garden, provided you keep its roots moist and avoid getting the leaves scorched by the midday sun.
Duranta repens (tian yod)
Not remotely similar is the golden dewdrop or pigeon berry (duranta repens). This woody shrub has smallish, purple, bright yellow or green leaves that, at a distance, can be mistaken for a mass of bloom. In fact, its pale violet flowers are, as with all these plants, upstaged by the foliage, but it does produce brilliant clusters of orange-yellow berries.
It is a real toughie, fast off the mark and with the twin advantages of thriving in full sun and of withstanding clipping. Indeed, it is usually grown as a hedge, often in conjunction with orange ixoras. A very useful coverer of bare spaces, it will, if allowed to express itself, attain a height of three metres.
Schefflera actinophylla (nuai phaamuk)
Sometimes available with dark green foliage, schefflera is normally now sold with attractive variegated leaves which combine yellow and green. Nothing unusual about that except that the umbrella plant is a must for any massed plantings which require banks of greenery. Extremely resilient and with neat, shiny leaflets arranged in whorls at the end of stems that resemble the ribs of an umbrella.
Schefflera will also survive life in a container, even when conditions are on the dry side. My specimen is large – a multi-stemmed bush about two metres tall and almost as wide. Propagate from cuttings, layering or seed. Available almost everywhere.
Patrick has been writing for thirteen years about gardening in Phuket and allied topics. If you have horticultural or environmental concerns, please contact him at firstname.lastname@example.org. Many of his earlier creative and academic publications can be found at Wordpress: Green Galoshes.