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How does your garden grow?  By Eric Danell, Dokmai Garden


A Cartoon bumblebee

It looks like a cartoon bumblebee – how else can I describe the flower of Aerides odorata (Orchidaceae)? It is thick and fleshy, the petals and sepals (spare the fleshy lip) all resemble wings and they are elegantly held in one plane. The spur really accentuates the shape of a wasp, being prominent and pointing forward. The flowers are white and pink, like small scoops of strawberry ice cream. t is native from the Himalayas to most of Southeast Asia and prefers a sunny position up in a tree, which is why a deciduous tree is a good choice in a Chiang Mai garden.

The side lobes of the lip are really tall, making the lip look swollen. The beak-like column reveals it is an orchid of the Aerides genus. It is in fact the type species on which the scientific genus description was made. The ‘eyes’ are the male pollinia hidden by a hymen which will open when the pollinating insect touches the ‘beak’.

The epithet ‘odorata’ implies a fragrance, but I have never felt any fragrance from any wild Thai variety, not even at night. I could be blocked to its fragrance, but I do catch the fragrance of other Aerides. With such a huge geographical range there is plenty of room for local adaptations and varieties.

Perhaps ‘Aerides odorata’ is in fact a cluster of several closely related species, each with its different morphology, colour scheme and chemistry as an adaptation to different pollination biology? Only molecular analyses of their DNA can reveal if there is a gene flow (mating) between the many different populations or not.

From the orchid conservation aspect it is important to work with local varieties, since a Himalayan variety might have problems surviving in a Borneo rain forest. The cloned strains grown for orchid houses abroad may degenerate quickly (i.e. develop new shapes, forms and fragrances selected by gardeners, not by nature) and so they provide little information of importance to science.

If any of our readers have experience from Thai wild strains and their fragrance, or have seen the presumably large insect needed to open the stiff flowers, please let me know. [email protected]

The Malaysian Pit Viper

Snakes are a reality to a monsoon gardener, even in towns and behind walls in gated communities. Although most Thai garden snakes are small and harmless to people, in fact beneficial by controlling rodents, treesparrows and snails, some snakes are potentially dangerous.

If you are bitten by a snake, it is good to know which species to get accurate and swift treatment at the hospital. The body of the pale Malayan pit viper has distinct dark triangles. The body is thick, compared to that of the marbled cat snake. Another harmless look-alike is the banded kukri snake, but that species lacks the IR pit and has a round pupil.

In a previous blog I treated the Indochinese spitting cobra. Yesterday Khun Nived picked up an upside down bucket on a stool and noticed a strange ‘stone’. When she looked closer she realized it was a snake. I was asked to come and take a look, and sure enough this was my first encounter with the pale form of the Malayan pit viper (Calloselasma rhodostoma, Viperidae, Crotalinae).

The snake was absolutely motionless, which is good and bad. It is good because it is not actively aggressive. It is bad because it trusts its camouflage so much that it will not move away like most other snakes, so if you put a hand or foot on it, it may bite. Luckily here in Chiang Mai there are good hospitals so the effects are usually not severe for an adult human, but without treatment you may lose a limb or even your life. I know of a gardener north of town who was bitten by this snake. He went to hospital but was back again at work the following day.

The pit viper venom contains compounds which lower the blood pressure (ACE inhibitors). This mechanism has been copied by modern science to make medicines against high blood pressure. Cilazapril is one such commercial medicine often used in Thailand against high blood pressure.

This relative of the rattlesnakes is nocturnal and hunts rodents but also other reptiles and amphibians. To be an efficient night hunter of rodents, it has a pit between the eye and the nostril which is sensitive to infra red, i.e. it can ‘see’ heat at night.

Being a foreigner in a Thai garden I have to accept the Thai culture. This snake was killed by Khun Densak for safety reasons, but I took the opportunity to study it more closely. The pupil of the eye is just a slit. The pit for infra red vision is clearly seen between the eye and the nose pit. The elegant ‘eyebrow’ is another diagnostic feature.

To keep snakes away from areas where you live, it is good to keep some chickens. They hunt young snakes. A sighting of a venomous snake should encourage the house owner to keep children and pets indoors until next day. To my experience tropical snakes come and go, they rarely stay in one area for long. Most snakebite patients are men bitten in their hands when trying to kill a snake. At Dokmai Garden there are snake-hunting mongoose, guinea fowl and raptors and so we have only seen the Malayan pit viper once in five years. Nobody has ever been bitten by any snake at Dokmai Garden. Remember that Nived must have been very close to this snake when she picked up the bucket – still nothing happened. I am more worried about traffic [email protected].

The Cuddly Cat Orchid is in blossom

A common native Thai orchid which do not mind six months of drought is the ‘cuddly cat orchid’ (Trichoglottis dawsoniana syn. Staurochilus dawsonianus, Orchidaceae). English vernacular names are needed to create an interest and concern about native Thai orchids also among tourists and foreign settlers. This vernacular name is derived from the lip looking like a yellow cat’s body stretching its paws for you, and the column which may resemble an animal’s face. An alternative name I have seen is ‘Dawson’s Staurochilus’, but I agree with André Schuiteman at Kew Gardens that the genus Staurochilus is superfluous and so the orchid should remain a Trichoglottis. In any case that vernacular name is not too different from the (obsolete) scientific name.

Being a father of four I am forced to learn about Pokemon (Japanese cartoon characters) and to me the orchid’s lip and column reminds me of the animal ‘Pikachu’. The colours, morphology and scent (undetectable to the human nose) are aimed at its special pollinating insect, still unknown to science. Since the orchid produces fruits at Dokmai Garden, the insect seems to be present too, although hitherto unknown to us.

Since this orchid species was successfully established in the Dokmai Garden monsoon woodland we are now in the process of moving out almost all specimens from the Orchid Ark nursery. Being a strong survivor in nature we do not think this species is in immediate danger in the Thai forests. It is a good beginner’s choice for somebody interested in growing native orchids in his monsoon garden. Simply buy it from a CITES certified dealer, mount it in a deciduous tree and allow it to follow the monsoon cycle, i.e. leave it alone.

Who was the ‘Dawson’ the German orchidologist Heinrich Gustav Reichenbach wanted to immortalize by creating ‘dawsoniana’ in 1868? One source claims it is after Dawson Turner (1775-1858), a botanist. That seems unlikely since that Dawson is a first name. Another source claims the orchid was named after orchid grower James Dawson of Meadow Bank, Glasgow, Scotland.  I think it is after Thomas Dawson Esq., an industrialist also from Meadow Bank near Glasgow, whose gardener James Anderson was an orchidologist corresponding with Charles Darwin. In 1868, the same year as ‘dawsoniana’ was coined, James Anderson received the Bateman medal for the greatest number of marks for orchids exhibited at the Royal Horticultural Society (England). “The wonderful Meadow Bank collection was then in its prime…” (From Lewis Castle (1886) Orchids, their structure, history and culture). It is possible that the gardener James Anderson has been confused with his patron Thomas Dawson and so ‘James Dawson’ became a fusion. If anyone knows for sure, please let me know. [email protected].

Blossom in the rainy season

To me, this is a rare garden plant, because you can not buy it anywhere.

This morning I woke up surrounded by the music of rain. An early morning stroll in the garden made me think how amazingly beautiful the rainy season is. The whole landscape has changed colours in just a couple of days. There are all shades of green, from the lightest yellow-green to a deeper maroon-green. A majestic Amorphophallus paeoniifolius (Araceae) is about to bloom, and the rare Firmiana colorata (Malvaceae) has already made new leaves (always looks dead in the dry season).

Unfortunately I slept too well last night, so when I woke up the rain meter was already full (35 mm). If I add those 35 mm to the continuous rain in the morning and lunch we have so far received at least 86 mm. This is not a problem, it is a blessing. The problems appear when we get such amount of precipitation in just one hour, like last year, twice!

This amount of rain will probably trigger termite swarms, frog choirs and in a  few days masses of mushrooms. It will also wake up zillions of butterflies. Many times I have remarked that of the 1000+ plant species at Dokmai Garden the South American ‘golden dew drop’ (Duranta erecta, Verbenaceae) is the main nectar plant for butterflies.  This year, for the first time, I have a native Thai competitor. I observed it in the jungle being surrounded by a cloud of butterflies so I returned later to collect seeds. They germinated easily and one sapling is now mature enough to bloom. This rainy morning I took the opportunity of sitting down with my literature to try to identify it.

Its fringed white petals revealed its affinity with the genus Elaeocarpus (Elaeocarpaceae). This is a tropical family you hardly find in Europe or North America, so only specialized botany professors from those areas would know about them. Llamas eminent book on tropical garden plants and Wikipedia do not treat this plant genus which encompass some 350 species. The Thais know them as ornamentals (Elaeocarpus grandiflorus) or jungle fruits. The scientific name is derived from the Greek word ‘elaia’ meaning ‘olive’ and ‘karpos’ meaning ‘fruit’. However, this plant is not related to the olive trees (Olea europaea, Oleaceae), it is a superficial resemblance used by Linnaeus who described the genus.

The key of the Flora of Thailand 2:409 (1981) is technical, and the species description contains no remarks on ethnobotanical uses. That key demands the use of a dissecting microscope. Still, it is useful to consult several different keys to identify a species, and so I used this key and also that of Gardner et al. (2007). Both keys point at the same species: Elaeocarpus lanceifolius. While Gardner et al. (2007) claim it blooms in June and that it is found at mid elevation 800-1200 meters altitude, that may reflect the experience of the authors. Flora of Thailand claims it is more frequent at 300-450 meters altitude which coincides with where I found it. My plant blooms now which is also in accordance with Flora of Thailand. Its mother site was in the evergreen valley of Mae Kanin Tai south of Chiang Mai, but it may grow even in Savannahs. The worldwide range encompass India and Southeast Asia including Indonesia.

The main features for identification are small flowers (1 cm diameter, 8 mm long petals), mainly arranged in racemes in axils of fallen leaves, below the tuft of young leaves. The leaves are smooth without swollen stalks. The anthers lack a bristle at its apex (aristate).

An obnoxious but impressive garden ant

There are about 12,000 species of ants hitherto described in the world, of which 247 species reside in Thailand, but many more remain to find. One ground dwelling ant which you find commonly in the Chiang Mai gardens is the ‘marauder ant’ Pheidologeton sp. It is easily identified by its trails with zillions of black, small workers which are happy to bite you, large workers and massive gigantic ‘soldiers’. A Thai name is simply ‘mot dam’ (black ant).

Teamwork! A small foraging marauder ant hitchhikes with a massive soldier of the same ant colony.

Marauder ants tend to make huge underground nests in sandy soils from which they launch foraging campaigns. This means that a certain spot in your garden may be clear from ants in the evening, but next morning when you walk about in kimono holding a cup of lovely coffee, your bare legs might be attacked by marauders and they do make you run and brush your legs. The massive soldiers move slowly like tractors so they are of little significance to the gardener. Like in the army, these living tractors may carry many small workers. They are also good at seed cracking and for towing larger prey.

Ants in general is one reason explaining the cleanliness of the Thai people. When a dirty farang like me resides for too long in a tent or room, the marauders happily invades your territory to liberate you from bread crumbs. Frequent cleaning is important to keep them away. Many animals feed on ants so a rich biodiversity in your garden may lower the numbers.

If an ant trail goes into your house because these hunters and gatherers spotted potato chips under your sofa, then pour some whiskey on their door step to wipe out the chemicals (pheromones) the ants use to find their way. This causes immediate chaos and proceed without delay with the vacuum cleaner to remove the invaders and their targets (dead spiders, pop corn etc). After counterattacking the immediate invasion, proceed by launching an attack on their head quarters. Many litres of boiling water poured rapidly from air borne tea pots may be sufficient. The aim is to eliminate the ant queen. Without a leader the nation will shatter and her mercenaries will get lost in the jungle. If this bombing is unsuccessful due to the depth of the fortress, you may want to try an ant specific bait. Although chemicals should be avoided, there are cases when it is either you or them. Unlike a gas which kills anything, a bait is specific and is brought home by workers which will poison the ant queen.

These ants are native and ecologically they do provide (other) pest control and also disperse seeds.

In previous articles I have mentioned three other common ants in Chiang Mai gardens: the exotic pharaoh ant, the exotic fire ant and the native red weaver ant which is food and often an ally in pest control. [email protected]

HEADLINES [click on headline to view story]

A Cartoon bumblebee

The Malaysian Pit Viper

The Cuddly Cat Orchid is in blossom

Blossom in the rainy season

An obnoxious but impressive garden ant