Zygopetalum Jumpin Jack

These are flowers from my plant of Zygopetalum Jumpin Jack, a hybrid registered by R. Murray in 1996. Like Zygopetalum species, this hybrid has jungly brown and green sepals and petals and a purple and white lip; this hybrid was probably chosen in part for its darker brown and purple colors. If you look closely, you will notice that it sometimes gets confused about which way is down (flowers in the background). Photos of two of the species likely to be part of the genetic background are posted at the bottom. 

This is a fairly large plant - mine currently has 8 cm egg-shaped pseudobulbs each with several long slightly plicate medium green leaves up to 45 cm long and 4 cm wide. Each flower is about 8 cm wide and they last about 5 weeks for me. The plant is vigorous and handsome even when not in flower and it flowers readily. Most Zygopetalum species are native to low and mid-elevation rainforest in Brazil, growing as terrestrials, lithophytes, and epiphytes, and their hybrids are popular houseplants, presumably because they are easy to grow and have spectacular flowers. Many also have a strong scent, variably described as similar to freesia or hyacinth. Mine has a rather weak scent, but it is also very distinctive - it smells to me just like freshly baked acorn squash with perhaps a touch of allspice. Weird. My daughter Zoé named him (and her) Jungle Jim, so that is our (unregistered) hybrid clone name: Zygopetallum Jumpin Jack 'Jungle Jim'. Jeepers!

I grow mine on the windowsill in bark mix in a plastic pot, with medium bright light, fairly wet, intermediate temperature, and no special care. Zygopetalum species and hybrids are reported generally as quite tolerant of growing conditions. If you are an orchid novice, I can heartily recommend them as starter plants - though I would suggest getting one that you have smelled in bloom as their scent varies a lot. I have smelled some that are strong enough to fill a large room and others with no scent at all.

My plant was acquired from Seattle Orchid and is an unnamed clone of this complex hybrid, with both parents also registered as hybrids. Many Zygopetalum species are quite similar in appearance and I did not try to track the parentage of this one all the way back to species. Here are two of the species that are likely part of the parentage:

Zygopetalum maxillare

Zygopetalum mackaii

Orchid Genome Sequences

In 2015 the first complete orchid genome sequence was published (doi:10.1038/ng.3149) and several others are on the way. The genome was for Phalaenopsis equestris but the main findings probably apply to most or all orchids. I won't talk about the results of this paper, which frankly, like most genome sequence papers these days, are a bit dull (although that is my professional area of work so they seem routine to me and would probably be highly technical and unreadable to you). What I will talk about instead is the astounding and ongoing drop in the cost of sequencing DNA and what it will mean for the future of ... drum roll please ... orchids. Not people! Who cares about people! Plus the promise of "personalized medicine" (roughly meaning medicine that takes into account your very own unique genome sequence) has been extensively written about and wildly over hyped in mainstream media. Here's what you can actually expect from personalized medicine: not much, or at least not for a very long time. Incremental improvements in a few cancer treatments and in judging appropriate drug dosages. That's it. Not even close to vaccines or antibiotics or good old segregation of sewage from drinking water.

Okay, now that I have offended most of the biomedical community, big pharma, little pharma, and half my readership, let's get down to things that matter: orchids. To do that I need to talk a bit about sequencing costs. Since DNA sequencing went large scale in the mid 1990s, the cost of determining the sequence of a segment of DNA has dropped by 4 or 5 orders of magnitude (factors of 10). This is a much faster gain than the famous Moore's Law for semiconductors on a chip. And the cost drop for now (2017) is continuing at about the same pace. It is likely that the cost of sequencing your (human) genome will be on the order of the cost of a postage stamp in a few years. (This is only the cost of running and amortizing the sequencing machine itself - at some point sample preparation, analysis of the output, and other ancillary activities will become more expensive than the sequencing itself.) Orchid genomes are substantially smaller than human genomes, so their cost will be proportionally smaller as well.

What does this mean for the hobby orchid grower? Well, mostly two things that I can think of at the moment. 1) All of that squabbling about taxonomic classification will be laid to rest (well, almost all of it). 2) No more need for misidentified plants, elaborate hybrid naming systems (and errors), and all of the aggravations that come with them. When you purchase a Dendrobium guerreroi 'CC9607' there will be no excuse for it being anything else. The frequency of these errors is high from what I can tell by reading responsible blogs from serious orchid growers. And the name Dendrobium guerreroi will stay Dendrobium guerreroi permanently. In theory, we can get rid of all these imprecise names altogether: you will simply say I have a "GCCTAGAATCGATC... [1 billion more letters]". Hmm, maybe that won't work.

If you are an orchid hybridizer, cheap DNA sequence could mean a lot more - being able to follow all the traits you care about through crosses without have to wait 10 years for a plant to mature. This won't be easy in the near term, but eventually the technology will assist in all kinds of directed breeding efforts, including make a hybrid Cattleya that is compact, grows fast, makes myriads of brilliantly colored flowers, tastes delicious, and whatever else you can track.

Though the cost of sequencing a genome will be very small, the machines and computers needed to get the sequence are still quite large and specialized, so for the time being you will generate sequence by sending samples to a center. A sample can be as small as snippet of leaf or root. There are handheld DNA sequencing machines available and/or on the near horizon but they are much more expensive per DNA sequence than the cheapest center-based technology. Nevertheless, we can probably expect a DNA sequencer in every, oh ... let's say library or corner store or something of that sort, in the near future. (Notice how I have cleverly used the vague term "near future" so that I can claim to be correct no matter what happens.) When will this all appear on your cell phone? Who knows, maybe never because it is too specialized, although it is possible I am not being imaginative enough. Not many people walk around thinking "I wonder whether the genome sequence of that dandelion is special in some way?". I do, but you probably don't. Unless you are odd and have a hobby like growing orchids.

Orchid Stomata, or how and why a plant can hold its breath all day

Q. What do orchids have in common with cacti and other arid climate plants? 
A. Their stomata and a special pattern of photosynthesis. (Well yes, they also are both grown by eccentric people, but that is the wrong answer and I am grading this exam.)

Most plants open their breathing pores (stomata, singular stoma) in the day and close them at night, but cacti and most orchids and a few other groups of plants open them at night and close them during the day. This night-open pattern is coupled with a biochemical pathway that allows these plants to use carbon dioxide in a special way. Most plants open their stomata during the day to enhance delivery of carbon dioxide to the photosynthetic chloroplasts. The "fixation" of carbon dioxide from the air using light is one of the defining adaptations of plants - the carbon in their stems, roots, leaves, and flowers all comes from carbon dioxide in the air. Our carbon does too, indirectly via plants. Okay, that makes sense - plants can only perform photosynthesis when there is light, so they open stomata to let carbon dioxide into the leaf when there is light and they close them up to conserve water at night, when they can't use the carbon dioxide anyway.

So how can orchids and cacti fix carbon dioxide? They hold their breath all day! Or more precisely, they only open their stomata when it is dark! First clearly demonstrated by Aubert in 1892 with many details worked out later by others, the key is that these plants open their stomata at night and store the carbon dioxide as the small molecule malate, then convert it back to carbon dioxide during the day. (Malate, by the way, is tart tasting and is abundant in many fruits including apples - genus Malus, from Latin for apple. The compound is named for apples.) Photosynthesis then uses the released carbon dioxide in the same way as nearly all plants do (via a cycle called C3 photosynthesis). The nighttime storage consumes energy, but the daytime photosynthesis captures more energy (from light) so the energetic balance is positive. For reasons that are more confusing than enlightening, this is called crassulacean acid metabolism or CAM. Short version: orchids take a great big breath at night and hold their breath all day.

Cacti and many other dry adapted plants use CAM because it allows them to keep their stomata closed during the hot daytime. This conserves water, which is inadvertently lost through the open stomata, much as we lose large amounts of water breathing. Cool night air lets them acquire carbon dioxide but lose little water.

Water vapor condensing from exhaled breath.

And why do orchids do the same, including ones that grow in wet cloud forests? Well, it is probably for the same reason - to conserve water. You should be crying foul about now: but my Masdevallia plant grows naturally in 90% humidity with daily rainfall! Despite this, epiphytes are often water challenged (though not as much as cacti) because they lack the large underground root systems that provide abundant water to most plants. Indeed, not only orchids but most other epiphytes, such as Bromeliads, use CAM. This water challenge also contributes to the fact that so many orchids have waxy thickened leaves or pseudobulbs. You may have noticed that a lot of orchids look like succulents, despite growing in wet areas.

And there you have it - cacti and orchids, sisters under the skin. And a blog post about orchids with human breath as the only picture. I am very proud of that.

Corallorhiza maculata - Orchid of the Month, June 2017

Corallorhiza maculata, Walter Siegmund, GNU licensed at Wikipedia

Corallorhiza maculata (Spotted Coralroot) is a very unusual orchid that grows on the ground in mountain woodlands throughout North America. In my native Pacific Northwest, it is locally abundant - the visible parts of the plants are erect coppery pannicles of small flowers. Close up, the flowers are brightly colored and showy but they are small and when hiking you notice at first the flower spike as a whole. The plant flowers in the spring but when the spikes dry up they stand like dead sentinels for months, so it is easy to see where coralroots grow even when not in flower, despite the fact that the rest of the plant is under ground. The genus Corallorhiza gets its name from the roots, which form dense clusters of stumpy projections, looking more like certain marine corals than our usual idea of roots.

Corallorhiza maculata, by Ron at nativeorchidsofthepacificnorthwest.blogspot

Dried flower spikes, Gerry Carr, Florida Flora Image Project

The flowers are lovely but what makes this orchid unusual is that it is mycoheterotrophic - it parasitizes fungi. Under the ground. Secretly. All over the forest. It is a conspiracy theorist's dream plant. It has no leaves, no chlorophyll, not even a hint of green anywhere. Except for the flower spikes it is invisible. Where I grew up in the Northeast U.S. a more common mycoheterotroph is the Indian Pipe (Monotropa uniflora, not an orchid), but in the Northwest coralroots are much more common.

As you may know, forest soil is packed with fungal mycelia (not the mushroom fruiting body, but the wispy white threads that form most of the fungus). Those fungi are mostly either saprophytic (living on decaying plant material) or mycorhizal (living as a mutualist with live plant roots). Corallorhiza maculata is reported to parasitize Russulaceae fungi, which themselves are mycorhizal with trees and shrubs (and produce Russula mushroom fruiting bodies above ground). The orchid somehow extracts a living from Russula mycelia as a parasite (not a mutualist).

Here is a fungus, which we usually think of as degrading things, being used as food by a plant, which we usually think of as the ultimate biological producers. And an orchid no less!

Sepals and Petals and Lips Oh My!

All orchids have 3 sepals and 3 petals, with one petal modified to form the "lip" or labellum. The ancestral condition (the flower structure of the last shared common ancestor of all orchids) likely had 3 identical sepals, forming an outer whorl which encases the flower during bud growth, and 3 identical petals, forming an inner whorl only revealed when the sepals open or are cut away. You can see this simple structure in the iris family Iridaceae, which is a close relative of the orchid family Orchidaceae. Though irises have their own complicated elaborations, they retain the 3 identical sepals (apparently called "falls" in horticulture) and 3 identical petals (called "standards"). In what was probably a key event in evolution of orchids, one the three petals was drastically modified and became the labellum.

The special structure of the lip is nearly impossible to ignore if you look at most orchid flowers, or read even the briefest article on orchid flowers. In many orchids, the other two petals are nearly identical to each other, as are the three sepals (to each other). But some orchids have a dramatically altered one of the sepals as well. Look at the Scaphosepalum flower below and try to figure out what parts you are looking at (yeah, yeah, most people just gasp and say "beautiful!" or "weird!" or "phallic!", but c'mon lets dig beneath the skin, plumb the depths of nature, and generally get all geeky).

Even if you are familiar with a lot of orchid flowers, you will probably have trouble telling what is what, and if you guess you will probably be wrong. This is one weird flower. The first confusing thing is that it is non-resupinate (the flower is not twisted around, so its lip is at the top, not the bottom as usual). The second really confusing thing is that the "dorsal" sepal (bottom sepal in this flower) is barely even recognizable - it is the purple projection sticking out like... well ya know. I thought at first that this was the lip, but in fact the lip is tiny and buried in the middle of the flower and is barely visible here. The two other sepals end in those yellow spikes, which look to me like the glorious waxed moustache of a vain blond Victorian gentleman. They also include a fused base that is sheet-like and spotted and forms the entire back of the flower from this view. Except for being long and narrow, the two types of sepals look almost nothing alike. By the way, the understated petals are the two small tan-gold flanges near the base of the modified sepal.

This genus of orchids has TWO totally different lips (yes, that is wrong term to use) - one of the three petals and one of the three sepals. Asymmetry of this sort is quite difficult to evolve, as molecular genetic studies show - it requires additional genes whose expression breaks the usual radially symmetric pattern of flowers. 

By the way, I am not aware of any information on why Scaphosepalum flowers look like this - some of them are even more exaggerated than this one (for example Scaphosepalum gibberosum and Scaphosepalum swertiifolium). Surely not to induce Victorian ladies swoon at the glorious moustache. Scaphosepalum are reported to be pollinated by small flies of some sort but really, what about this looks like it is meant to attract flies? It doesn't look (or smell) like a fruit (fruit flies), or a fungus (fungus gnats), or dung (dung flies), or rotting meat (corpse flies). A fly that admires abstract sculptures? That must be it.

Supine, Resupine, and Reresupine

One of the many lines of evidence supporting the ancient origin of life and its evolution by modification and natural selection is the pervasiveness of workaround solutions in biology. For examples: land vertebrates breath and swallow using the same tube (the 3,000 US citizens who die each year from choking on food unanimously agree with me that this is a terrible design); the blood supply and connective tissue in the vertebrate retina is in front of the light detecting cells; wisdom teeth; the panda's thumb; and a zillion less familiar examples.

Orchids also provide examples, perhaps the best of which is the twisting of flowers during bud development to situate the lip of the flower either above or (more commonly) below the rest of the flower. The lip is a highly modified petal that ancestrally was in the dorsal position (at the "top" of the flower). A great deal of the diversity of orchid pollination depends on elaborations of the amazing lip structure, but that is another story. Some orchids position their lip at the top of the flower (e.g. Prosthechea cochleata, below), but most position their lip at the bottom of the flower to act as a gravity-assisted landing pad for their pollinators. 

Prosthechea cochleata, from Wikimedia Commons

This "lip at the bottom" form is called resupinate (meaning literally: again brought to lie on the back with face up). If you look closely at the stem holding your favorite orchid flower you may be able to make out how this happens: the lip starts out dorsally (when the bud has just begun to form) and the flower stem twists around 180° before opening. Many orchid flower stems have ridges that make this apparent in the mature flower, obvious in the flower facing left in the photo below. The twist is usually most obvious near the base of the stem so you may have trim away the bract covering the stem base to see the twist. (Unfortunately the common Phalaenopsis that I have inspected have nearly perfectly cylindrical flower stems so the twist is very hard to see.) This is The Exorcist head-twisting approach to lip positioning.

Anacamptis picta var. alba from wildnaturespain.blogspot

Okay, so far this is fairly strange - the lip forms on the top of the flower and then the flower twists around to get the lip on the bottom where it has to be to facilitate pollination. But here is the kicker: some orchid flowers (e.g. Angraecum superbum, also called A. eburneum) that are non-resupinate (lip at the top) start with the lip at the top, then twist it around 360° as the flower grows! Let me restate this bizarre fact: the lip starts where it should be, then twists around to where it shouldn't be, then keeps right on twisting around until it is back exactly where it started. How did this happen? Nobody is sure, but most likely these species have ancestors that are resupinate (lip at the bottom) but something changed that made it advantageous for the lip to be at the top. There are two ways to adapt to this change: eliminate the twist altogether, or continue the twist for twice as far. Apparently the second possibility is what actually happened, at least in some cases - what Steven Jay Gould called contingency or historical contingency. Charles Darwin noted the 360° twist in Angraecum superbum and used it as an argument for evolution (not natural selection necessarily, but an historical process evident in current life).

It would be interesting to find a study of what fraction of non-resupinate flowers have no twist vs. the double twist. Anybody known of cases? I have not heard of a flower that is resupinate with a 1.5 twist (540°) - it would presumably have evolved from an ancestor that had 1 twist, which had an ancestor with 0.5 twists, which had an ancestor with no twists. Vizzini of The Princess Bride would have loved that one if he had survived the poison duel.

Orchids from Seed and Symbiotic Fungi

Orchid seeds are tiny and have no stockpiled nutrients to help them start growing. This condition is probably an adaptation to allow production of huge numbers of seeds at low cost, and for allowing them be spread easily by wind. (In case you never noticed, avocados go to the other extreme, much to the consternation of epicures.) The vast majority of seeds end up in an inhospitable place and never germinate - this is true for many plants but it is probably more extreme for orchids. Even when an orchid seed lands in a prime spot, for example lodged in a crevice in damp bark with the right sun exposure and at the right altitude, its trials are not over. There the seed needs to encounter a symbiotic fungus that will provide sugar to get growth started (later the orchid will reciprocate but as far as I have read this street starts off one-way). The seeds need various other nutrients just like all plants, but it is mostly sugar that is provided by the fungus (or other small organic molecules in some cases) - sufficient minerals leach into the rainwater after it falls. The seeds do not carry the fungus with them - perhaps the fungi are widespread enough to make it unnecessary or perhaps it is hard to evolve a fungus-carrying seed. Once the tiny orchid plant starts photosynthesis it can fix carbon from the air, but it can't get to that point on its own.

In the early days of orchid horticulture, before all this was known, attempts to grow orchid seeds were miserable failures. The seeds just sat there or grew mold, quietly mocking the botanists and Victorian millionaires. For a few orchids, it was noticed that seed would sprout if it was just next to the parent plant, which provided an early tip that something else was necessary - something associated with the parent plant. In 1909, Bernard discovered that germinating orchid seeds depend on a mycorhizal fungus (more abundant near the parent plant), but this discovery did little to improve the practical problem for horticulturists. Finally, in 1922 Knudson showed that many orchid seeds would germinate on a defined medium containing nothing but a few salts and sugar. The orchids don't need the fungus - they only need the sugar the fungus provides! This was the breakthrough for humans trying to raise orchids from seed, though precise definition of the optimal salts and organic compounds for different types of orchids is still being worked out.

Since Knudson, orchid seed is grown aseptically with only appropriate salts and sugars (and light and air) provided, typically with agar to provide a gel base. The method is common enough that you can find many how-to guides for the process and you can even buy prepared commercial agar medium to get started. The process is still a bit involved because bacteria and (bad) fungi also love this medium and will kill the slow-growing orchid embryo, so you have get rid of the bad guys. With care though, apparently you can do this in your kitchen with only a pressure cooker for sterilizing media and minimal laboratory equipment such as glass flasks.

Development from seed to adult flowering plant is still agonizingly slow, but at least it is routine. As you know if you grow orchids yourself, pretty much everything about orchids happens in slow motion. Some orchids take 10 years to go from seed to flowering plant, about the same as small trees. Some grow one new leaf per year. No bean or basil or avocado seedlings in the orchid world! Nearly all orchids are highly adapted to very low nutrient conditions, so only slow growth works. Even most terrestrial orchids occur in low nutrient environments and follow the same rule. Some types of orchids make impressively rapid growth at the start of their wet season (e.g. Catasetum and relatives), but this is deceptive - they are converting nutrients from their fat pseudobulbs from the previous year, painstakingly acquired over the growing season. Their averaged growth rate is much less impressive. I suspect this slow growth is part of the magic of orchids - how can a plant that hardly seems to do anything at all from week to week produce these amazing flowers!? That will be another post - there is an answer.

As ye sow, so shall ye reap. But be sure to add sugar.

Dendrophylax lindenii - Orchid of the Month, May 2017

Dendrophylax lindenii by Mick Fournier,
Pompano Beach, Florida

Here is an orchid that has it all - strangeness, rarity, fragrance, and a drop-dead gorgeous flower. Dendrophylax lindenii, the Ghost Orchid, is a leafless orchid that grows epiphytically on the trunks of trees in swampy lowland forests in south Florida and some Caribbean islands. The entire genus Dendrophylax is leafless and they perform photosynthesis with their roots, as do a number of related genera from Africa and Madagascar. The roots are flattened and grow uncovered and plastered against tree bark; in their natural condition they look a lot like a Phalaenopsis with most of the stem and all the leaves torn off (in fact, some Phalaenopsis species are nearly leafless). The loss of leaves in these orchids is probably an adaptation to a seasonally dry climate.

Many Dendrophylax species have lovely flowers, but those of D. lindenii are especially large, graceful, and unusual in form. They have a long curved flower spur and are said to be pollinated by the long-proboscised (long-tongued? long-proboscis owning? well-proboscis-endowed?) sphinx moth Cocytius antaeus, which is seeking the nectar hidden away at the end of the spur [note - I have not yet been able to track this claim to a primary source]. This coadaptation is reminiscent of Angraecum sesquipedale from Madagascar, which was famously predicted by Charles Darwin to be pollinated by a moth with a very long proboscis, because its flower is white, nocturnally fragrant, and has a very long nectar-bearing spur. Unlike D. lindenii though, A. sesquipedale is endowed with abundant dark green leaves.

A few commonly cultivated orchids appear to be leafless when in flower because they are deciduous and flower in their leafless phase (some Lycaste, Mormodes, Clowesia, and Dendrobium species). These plants are remarkable looking when in bloom - a few half-dead looking pseudobulbs mysteriously shooting out a plethora of flowers.

Mormodes paraensis, photo by QT Luong

Dendrophylax lindenii is endangered and should never be collected from the wild. They are also notoriously difficult to grow in culture and you should not acquire one unless you are well informed and committed to its care and you know the plant was raised from seed in captivity. If you want to grow a leafless orchid, choose one that is more easily grown, such as a Chiloschista species.

Unlike most orchid species, there is a good Wikipedia article on Dendrophylax lindenii, which provides some additional technical information but lacks the wit, grace, and brilliant insight (meandering hodgepodgieness) of my blog posts.

Orchidarium 3

The new intermediate orchidarium continues to come together slowly. Below is a photo of the current state. The grapewood burls have been fastened together and put in their permanent location and a few additional plants added. Gradually I will be mounting plants directly on the grapewood and hanging others from it, with pots sitting on the tray at the bottom. The purpose is to have something that looks reasonably natural but with some of the plants easily removable for display and photography. I plan to be cautious mounting directly on the grapewood because it will be harder to reverse and I want to be sure they have the right light exposure. Grapewood is reputed to be very rot resistant, but of course eventually the whole thing will have to be replaced, which will be a big pain in the neck.

Currently in the case are:

Amesiella monticola
Bulbophyllum pecten-veneris var. tingabarinum
Dendrobium laevifolium
Dracula lotax
Haraella retrocalla
Macodes petola 
Masdevalia rolfeana
Masdevalia sernae
Mediocalcar decoratum 
Restrepia brachypus
Restrepia elegans
Scaphosepalum brevi
Specklinia grobyi
Specklinia picta (possibly misidentified)
plus three species of minute epiphytic ferns

Plants I plan to add include:
Diodonopsis erinacea 
Lepanthes calodictyon 
Masdevallia hirtzii (a showy one!)
Stelis pilosa
Tristella hojieri 

[It won't surprise me if some of the plants were misidentified by the retailers as this seems to be a common problem, but the foliage for all but one of them looks right and the three that have bloomed so far appear correct. The Specklinia picta is confusing - the flower looks exactly right but the leaves are narrowly linear, which I can't find reported anywhere.]

All have been chosen to be small to very small, and tolerant of intermediate temperatures and modest light exposure. I have also avoided anything reputed to be really hard to grow, or at least I think I have. Most are not particularly "showy" because for this Wardian case I am more focused on diversity and peculiarity than beauty (by most human standards). I have lots of other orchids on windowsills that have big bright flowers, so I get my fill of showy stuff. Despite my mediocre photo postings thus far, I have good camera equipment and reasonable skills and I will post macro shots of plants and flowers as things come along. In the meantime get your fill of gorgeous photos of gorgeous flowers at the blogs "Orchids in Bloom" and "OrchidKarma".

Orchidarium 6/3/2017

Throwing Spears and Snapping Lips

Plants wave in the breeze, bend toward light, and gradually furl and unfurl their parts, though Usain Bolt doesn't spend his time worrying about competition from plants. But at least two groups of orchids have evolved fairly speedy movements, at least by plant standards (admittedly not that high). Both occur in flowers and both involve manipulating pollinators.

Male Catasetum genus flowers fire their sticky pollinia when a trigger hair is disturbed. The motion is so fast it is hard to see in real time (move over Usain!). Under natural conditions the flower hopes they stick to the male euglossine bee that was investigating the flower, and that the bee will later visit a female flower and complete their rather tenuous copulation. If you use a well-positioned toothpick to activate the trigger, the pollinia will shoot halfway across the room. Catasetum, by the way, is one of the few orchid groups that have separate male and female flowers, usually found on separate plants. Most orchids are bisexual (also called perfect), with both pollen and ovary carried on the same flower, though they usually don't self-fertilize. Like birds of paradise, it is the male flowers that are showy - the female flowers are typically smaller and green and look a bit like a Little Green Riding Hood. 

Porroglossum genus flowers are slower, but their plan is similar - attach sticky pollinia to a pollinating fly. The entire lip of a Porroglossum flower is hinged and when sufficiently disturbed it snaps up against the column, trapping the fly in place for pollen transfer either onto or off of the fly. Okay, "snaps" is a bit strong - we are not talking great white shark or chameleon tongue here. How about "closes up against the column". It typically takes several seconds, but apparently it is enough to trap a fly (move over Mr. Miyagi!). I am speculating now, but maybe if it moved faster it would scare the fly into flight. In any case, the lip opens again after several minutes, releasing the insect. The hapless fly presumably suffers briefly with post-traumatic stress syndrome, but eventually recovers enough to deliver its precious pay load to another snapping flower. And right back into psychotherapy for our doubly duped Dipteran.

You can find videos of both of these actions if you poke around on the web. I have a Porroglossum plant and will make a video when it flowers and post it on this blog!

Water Culture for Phalaenopsis

[ In case you don't read the whole post - I ended this experiment after 5 weeks when all the roots on one of the plants rotted. And I mean ALL, see photo at the end. The other two plants weren't quite as bad, but they appeared to be heading the same way, so I stopped the experiment with all of them. As several others have found with their experiments (which I knew about and ignored), do NOT USE water culture, or use at your own risk! Despite my elaborate rationale, which I have left intact below, clearly this is not a good plan, or at least not the way I did it. Yes, Phalaenopsis are not aquatic. I should add that this experiment does not rule out the possibility that new roots would be better adapted for growth in water, but I elected to save my plants. ]

Photo from http://www.phals.net/honghenensis/honghenensis-in-situ 

I have had three Phalaenopsis hybrids for many years, and they have done fine in the usual mixed bark planting medium, but I recently decided to try them in water culture. I will report on how the plants do over time. I don't know how generally pure water culture will work for orchids - probably not well for most. Growing in inert media such as sponge rock, expanded clay, or charcoal seems to work fine for a wide range of epiphytic orchids, but the water/air/root dynamic under those conditions is much more like traditional media.

I got started with the idea of water culture due to one Phalaenopsis hybrid in my work office, where humidity is very low. I was growing it cased in a sealed pot sitting in a shallow bowl of water, hoping to keep local humidity up a bit, and as it grew aerial roots I started tucking their ends into the water hoping to keep it happy. The roots clearly loved being in the water - they grew fast and they looked fat and sassy and they were bright green. The plant thrived. Yes, it is a grocery store hybrid Phalaenopsis (i.e. only my friend Theresa is capable of killing it) and most of the plant is still in bark medium in a pot, but the idea germinated of tossing the pot and growing in a bowl of water.
Look at the roots in the in situ photo, photographed in situ in mountains in Burma growing low on the trunk of a tree (the roots are the silvery green ribbons plastered all over the bark). This species of Phalaenopsis has very few leaves and apparently does much of its photosynthesis with its roots. Most Phalaenopsis species have more leaves but they all have light-exposed greenish roots, and a few species are leafless or seasonally leafless. Their roots provide most or all of the photosynthesis. Growing Phalaenopsis mounted directly on tree bark is most natural, but it isn't convenient unless you happen to live in the right place or have a greenhouse and are willing to wet them every day.


Back at home with my test plants: the containers I am using for my full water culture trial are glass bowls that are approximately spherical with a slice off the top of the sphere. This sort of vase is relatively easy to find on-line - a search at [a certain large retailer named for a South American river] for "glass bowl vase" finds them readily. The idea is that the narrow mouth will support the plant and keep the humidity inside the container high and the clear sides will allow the roots to green up and become photosynthetic, which is the natural condition of Phalaenopsis plants in the wild. The broad leaves of the plant rest on top of the vase and the entire plant body and most of the roots are not immersed. The roots would never naturally grow under water, but keeping the water very shallow will hopefully keep them well aerated. The base of the plant stem is at least 5 cm from the water and it is dry. The root core presumably transports water up the leaves but the root velamen is dry to the touch above the water line. I will be surprised if I have a problem with stem rot as others have reported for their tests. The setup I am using would be harder to arrange for plants with different shapes, but for Phalaenopsis in the right sized bowl they just sit that way naturally.

Phalaenopsis unknown hybrid day 1 (5/11/2017)

I am using a rather small amount of deionized water in the bowl (about 2 cm deep) with a bit of complete fertilizer added (the kind designed for pure water - it has calcium and magnesium and all the trace elements in addition to all the usual stuff. Don't you just love that plants require molybdenum? What!?). Tap water is probably fine too as long as it doesn't have a lot of dissolved minerals. I dump the water out for a day or two once a week, as various sources on the web suggest - the idea is to inhibit too much bacterial and fungal growth and to mimic occasional dryness in nature.

The photo above is one of my plants, for which I am keeping a photographic record. This plant just came out of bark medium and you can see that most of the roots are bone white, with only a few green bits - the parts that were aerial when potted. Two weeks later, as I write this post, the roots are already getting a pale green blush - I will update or make a new post when the difference is more obvious. So far no roots have died.

As a side note, it is interesting that the natural plant (above) is growing "sideways" - from pictures and comments I have found on the web, this is usual for Phalaenopsis, and quite often they grow slanting downward or even completely upside down (how the seeds stick and germinate on the bottom of a branch I don't know). This explains why culture guides warn that you risk rot if you wet the growing crown of Phalaenopsis, yet natural rain doesn't present a problem. They don't grow right side up! Um well, we don't grow them right side up.

And ... experiment over because here are the roots after 5 weeks (I cut them off as they rotted one by one, but I stuck with it to the bitter end). You can't see the plant leaves above, but this is the same plant - I just moved it temporarily to rescue spaghnum moss and my experience is that it will recover without much trouble because it is a Phalaenopsis hybrid and they are tanks. If you look closely you can see one new root tip, which started while still in water culture.

Same plant on 6/17/2017

Cheating Orchids (Flower Mimics)

In an intelligently designed world (which ours is not), every flower would offer a reward to its pollinators - you scratch my back and I'll scratch yours (technically called mutualism). Why else would a pollinator be willing to visit flower after flower, inadvertently transferring pollen?

Many orchid flowers violate this sort of reciprocity using a variety of tricks, famously including forming insect mimics to induce insects to attempt to mate with the flowers. I recently read about one trick I hadn't heard of before, at least among orchids (reference below). Two different orchids, Cymbidium insigne and Dendrobium infundibulum, appear to mimic a Rhododendron flower, allowing them to get away without offering the usual nectar reward. The Rhododendron (Rhododendron lyi) and the two orchids have the same range in mountains of northern Thailand. They bloom at the same season and all three are visited by the same bee species (Bombus eximius). The flowers of all three appear quite similar (photos below - they aren't hard for us to tell apart but remember they only have to fool the bee). But only the rhododendron flower produces nectar! No direct proof has been published, but it is likely that both orchids have evolved flowers that are similar to the Rhododendron and have been able to forego the metabolic cost of producing nectar. As long as the Rhododendron flowers are more common than the orchids, this sort of mimicry is thought to be feasible.

The orchids are cheaters and, as long as the Rhododendron and the bees are around and the bees don't catch on, they will no doubt continue their cheating ways. There is risk for the orchids - if the bee or the Rhododendron go extinct the orchids may be doomed as well. These sorts of interdependencies are common in nature, especially in stable warm climates. Evolution does not plan ahead.

It would be interesting to know if a minority of the orchid flowers still make a little nectar (even rare orchids making a very small amount), or if the ability to make nectar has been lost completely (as humans completely lost the ability to make Vitamin C during a period when our ancestors ate mostly fruit). If nectar production is still possible, then the orchids could probably survive loss of the Rhododendron flowers - natural selection to reward pollinators would kick in again and orchids that make more nectar would gradually increase. For we humans, the genes that encode Vitamin C synthesizing enzymes are completely dead (technically called pseudogenes) and without technological intervention we will never make Vitamin C again.

Rhododendron lyi (photo by Marc Colombel)

Dendrobium infundibulum (photo by Marble Branch Farms)

Cymbidium insigne (photo by Simon Pugh-Jones)

Gosta Kjellsson, Finn N. Rasmussen and David Dupuy Journal of Tropical Ecology Vol. 1, No. 4 (Nov., 1985), pp. 289-302