The Poetry of Dendrobium moniliforme (Choseiran)

Dendrobium moniliforme, called Sekkoku or Choseiran in Japan, is a small caning Dendrobium that has been cultivated for centuries in Japan. Though less well known in the west than its botanical second cousin Vanda (Neofinetia) falcata (Furan or Fuukiran), Dendrobium moniliforme also has an extensive history in Japan of appreciation and selection of botanical varieties. There are various cane heights, cane colors, leaf shapes, leaf colors and variegations, and flower colors. As with Vanda falcata, a few of them are just plain weird, but most of the varieties are lovely little plants.

I have quite a few Vanda falcata but I resisted purchasing Dendrobium moniliforme because they looked kind of ragged and leggy, as caning Dendrobiums are wont to be. A short while ago I purchased a D. moniliforme 'Kosetsu' plant, a fairly typical white flowered variety with plain green leaves and canes, probably not much different from the common wild form other than being on the small side. It was love at first sight. A simple description of my plant or even the photo below fails to convey what enchanted me, but I will try to give you a sense with a prose poetic description (please forgive my amateur attempt).

A stand of ancient trunks densely clustered on a hill, clothed in papery wrapping, shredded and worn, revealing smooth maroon skin. Most are proudly erect, but one kinks a bit as if staggering under the weight of age. In the midst of the ancient ones, two vibrant green youths stand tall, shouting with exuberance, their skin green and tight on their canes and their leaves tender and graceful, unaware that they will soon shed their leaves and join the ranks of the ancient ones. In time, the ancient ones will bear pristine white scented flowers for a few weeks, and then will return to their mute and papered form, each year becoming more shriveled and shredded until they can bear flowers no more. In a month or a year, new youthful canes will push up and exclaim in green that life endures, life persists, life prevails.

That is what my plant says to me. Though I can find very little English literature on the plant, it seems likely to me that similar sentiments are found in Japanese. This is the bonsai of orchids.

Oncidium sotoanum, Orchid of the Month, September 2017

Oncidium sotoanum (known for a long time as O. ornithorhynchum, but recently subject to one of those annoying "precedence" squabbles that seem to be so important to some) is a moderately large plant with a typical Oncidium growth habit: large flattened pseudobulbs, long thin-textured leaves, and seasonally large branching panicles of small flowers. It is reported to grow in northern Central America in humid tropical rain forests at elevations up to 1500 meters. The species is most famous for its strong sweet fragrance, variably described as vanilla, chocolate, or Fruity Pebbles cereal. I would prefer to say that Fruity Pebbles cereal (one of the many triumphs of American marketing, with the goal of making money by damaging the health and aesthetics of world youth - go marketers!) smells like Oncidium sotoanum.

Specimen Oncidium sotoanum plant grown as an ornamental.

Though the Oncidium sotoanum flower is lovely and smells divine, the species is probably better indirectly known for hybrids in which it dominates, including Oncidium Sharry Baby and Oncidium Twinkle. Both of these hybrids have flower panicles and flowers that resemble O. sotoanum except for color, and both are among the most famous hybrids in the orchid grower's world for their scent.

Presumably this famous scent is intended to attract pollinators, probably male Euglossine bees, which are scent collecting bees often associated with orchids. The scent oils in O. sotoanum are produced by specialized flower cells called elaiophores (from ancient Greek "oil bearer") which form the surface of ridges and pillars near the base of the lip, easily visible in the photo below. This part of the lip is a contrasting yellow or orange color, presumably as a cue to bees in locating the oil. The orchid's purpose, as usual, is to attract and then position these bees so that they pick up and drop off pollinia. Unlike many orchids, this one provides something that the bees want (they in turn use the oils to attract female bees, but that is another story).

Single Oncidium sotoanum (with the old species label) flower, showing the yellow-orange callus where scent oils are produced - notice its proximity to the pollinia, which are not visible but are adjacent to the white patch just above the callus. Photo from IOSPE (Jay Pfahl).

This flower along with many others raises an interesting question: why do so many flowers smell good to humans? Not all do of course, witness the famous corpse flower and many similarly scented flowers, intended to attract carrion flies. However, I think it is fair to say that a randomly chosen scented flower will smell pleasant, or at least intriguing, to most humans. Clearly this has nothing directly to do with us - these flowers have evolved to produce a huge variety of volatile compounds to attract pollinators, usually insects, bats, hummingbirds, and the like, but certainly not humans. It is hard to avoid, but also hard to prove, the conclusion that we have evolved to like the scent of flowers and not the other way around. But why? We don't eat them, we don't defend ourselves with them, indeed they seem altogether useless in every way except aesthetically. Perhaps humans evolved to like the scent so that individuals could pick them and elicit sex by presenting them to their amorous choice, much like Euglossine bees? Certainly that is one of their primary uses in current cultures, although rarely stated so baldly. I suppose this is just barely plausible, though it seems a stretch. More likely, flowers act as cues for the eventual location of fruit, a favorite food of a wide variety of monkeys and apes, including us. Hard to test, but fun to think about. Meantime, if you grow orchids, get this species or one of its hybrids - they smell divine.

Pesticides: 100% all natural

Here is a topic that generates a lot of heat and little light. The conventional view among the liberal crowd that I mostly hang out with is that natural is good and man-made is bad. This view is laughably ignorant and sometimes downright dangerous. It is perfectly sound to assess the safety of chemicals, for humans and for other animals and plants, both short term and long term. The ignorance comes with the idea that natural is safe and unnatural is not. In fact, the safety of any product has to be assessed regardless of origin.

If this raises your hackles, let me tell you a story. When I was a kid, one of the home remedy ways to treat my cacti for insects was to exhale cigarette smoke under an inverted jar with the cactus under it, and let it sit for some time (not that I actually did this, but I read about it). Now this is a perfectly sensible method - tobacco smoke contains nicotine, which is a very effective broad spectrum insecticide. Indeed, it is thought that tobaccos (and related plants) make nicotine to kill their insect pests. On a larger scale, nicotine was a major agricultural pesticide from about 1945 through 1980. Nicotine is all natural and totally "organic", but it has a problem - to mammals it is acutely poisonous. The only reason cigarette smokers don't drop dead after a few puffs is because tobacco smoke contains only small amounts of nicotine. Though it was never banned in the U.S., it is no longer in use as a pesticide because of its toxicity.

Here is a (very) partial list of other 100% all natural chemicals that are very hazardous in some way, with their broad class of toxicity and natural source in parentheses: aflatoxin (carcinogen, fungus), ergot alkaloids (neurotoxin, fungus), ricin (cytotoxin, plant), aconitine (neurotoxin, plant), arecholine (neurotoxin, plant), atropine (neurotoxin, plant), scopolamine (neurotoxin, plant), amanitin (cytotoxin, fungus), coniine (neurotoxin, plant), delsoline (neurotoxin, plant), colchicine (cytotoxin, plant), anabasine (neurotoxin, plant), ptaquiloside (carcinogen, plant), ouabain (cardiotoxin, plant), strychnine (neurotoxin, plant), morphine (neurotoxin, plant), and last but not least botulinum toxin (neurotoxin, bacterium), which is the most acutely lethal toxin known (in humans, about 100 nanograms is lethal when injected, a speck of the chemical too small to see by eye). And I am leaving entirely out of the list toxins produced by animals for hunting (snakes, cone snails, and many others) or defense (poison arrow frogs and many others), and irritants (urushiol from poison ivy being the most famous in the U.S.).

All of the above listed chemicals are most likely produced defensively, to prevent contact with or ingestion of the producing organism. They are the product of evolution, which has had notably outstanding success at producing toxins because they are so useful as defensive and offensive weapons. Most of the plant chemicals probably have insects as their main target, because they are the most damaging herbivores. However, in most cases all complex animals share with insects the target of the toxins, so they are often toxic to varying degrees to many or most animals.

This is not to say that man-made chemicals aren't dangerous - everyone is well aware that we have contributed our own ingenious toxins to the huge panoply of natural toxins, sometimes with more enthusiasm than wisdom. In short, each case has to be taken on its own merits (killing intended organisms) and demerits (killing other things). Rather than depending on the idea that natural products are safe, you should assess each chemical by using the amazing amount of information readily available on reputable sources like Wikipedia and government-sponsored toxicity pages.

For the most part, commercially available pesticides (natural or not) are relatively safe because they have been tested for their effects on fish, birds, mammals, etc., though both natural and synthetic pesticides should always be used with care, especially aerosols if they are sprayed. Pesticides allowed for home use are typically safer (it is easy to tell when they are not - if the smallest amount you can buy is huge and costs a bundle, it is NOT licensed for the home). Some are safer than others - again, look it up. You can make your own choice about what you consider acceptable risk for you, your pets, honeybees, fish, or whatever else you care about, but don't fall into the "natural is safe" trap.