The Pleurothallids

 The Pleurothallidinae is a large subtribe of the Orchid family (Orchidaceae). In this New World group are found some 30 genera and over 4000 species, many of which are uncommon in cultivation. The largest genus by far is Pleurothallis having about half of the described species. The generic names Masdevallia, Pleurothallis and Zootrophion immediately bring a favorite image to mind but some other genera are more obscure and may be more difficult to visualize. Many of the Pleurothallidinae are miniature. Most inhabit cool, high altitude forests where they are regularly exposed to fog and mist, but there are some suited to the average even warm-growing collection and a few have adapted to seasonally dry conditions.

The plant and flower structure set the Pleurothallids apart from other orchids and is quite intriguing in its own right. Whether short or tall, tufted or vining plants, all members of this group have thin stems (ramicauls) each topped with a single leaf. Those of you who own a pleurothallid are encouraged to examine it closely for the distinctive parts. The ramicaul is essentially a slender upright stem of variable length. The juncture between the leaf stem and the ramicaul can easily be located although it may sometimes be necessary to remove the thin sometimes papery surrounding sheath. This point is the abscission layer and from whence leaves break off especially when plants are stressed. In many species including many of those of the genus Pleurothallis, the inflorescence appears to arise from the base of the leaf but in fact, the flower stem is arising from a point below the juncture of the ramicaul and the leaf stalk (petiole). The place where the inflorescence arises is termed the annulus. Once a flower fades, the entire flower including the ovary is deciduous. In Restrepia, Zootrophion, and some other genera, a plantlet may form in place of flowers and this may later be removed as a vegetative propagation or left attached where it will flower when sufficiently mature.

Pleurothallid blooms have several features in common. Sepals are typically the more obvious floral structures: petals are often reduced and difficult to see. In Octomeria, petals and sepals are more or less equal in size and appearance. The pleurothallid lip varies greatly in terms of shape and function across the genera. In Dracula, lips can resemble gilled bracket fungi. In Restrepia, the showy lip-like structure is in fact the synsepal. In the Oscillantes subsection of the genus Masdevallia, the lip is hinged loosely so that it bobbles about with the slightest breeze. The tiny dark red lip of Pleurothallis sertularioides produces droplets which could serve to attract pollinators. Perhaps it is the vast diversity of flower and plant form that attracts the orchidophile to the pleurothallids. Regrettably, both loss of habitat and over collection of unique populations have taken their toll. Pleurothallid fanciers should do everything possible to ensure that species already in cultivation are not lost.

Masdevallia (350+ species)
Masdevallia nidifica is a miniature species that reveals some of the common traits of this interesting genus. The somewhat elongate leaves are produced from short ramicauls. From within a sheathing bract which hides the leaf base, there arise one to several single-flowered inflorescences. The flowers are variably translucent ranging from pale yellowish green to pink with contrasting maroon stripes. This showy part of the flower is composed of the sepals which are tailed. The petals lie on either side and are about the same length as the column. The ovary is curiously winged. If we remove half of the flower, we can see the extended and curved column foot which supports the tiny lip.

Dryadella (40+ species)
Members of this genus resemble Masdevallia and were known by this name previously. The major differences lie with the lip structure. Where a lip of Masdevallia is tongue-like, in Dryadella, the lip is ornamented with two protrusions (calli) and two backward-facing points or claws. In Dryadella edwardii, we find a floriferous plant with heavily spotted, Masdevallia-like flowers.

Lepanthes (600+ species)
This large and variable genus is sometimes challenging to identify when plants are immature. Typically, a flat oval leaf carries one or more inflorescences from below its point of connection with the ramicaul. The ramicaul is enclosed with a series of overlapping papery tubular sheaths. But it the bizarre and often brightly colored flowers that attract the eye. They are intricate also such that it is a challenge to distinguish floral parts. The largest parts are the sepals but the most colorful are often the petals and the intricate lip. Here we see Lepanthes oaxacana, a particularly dark and showy flower. Photograph by EW Greenwood. (Please note that the Lepanthes picture is inverted. I apologize for this.) This species is Mexican. The flowers are produced singly on long branched inflorescences.

Beneath all of this is the column and the reproductive parts of the flowers. Here we see a flower of the very rare Lepanthes sousae as viewed from the side. You can see the projecting column surrounded by the lip. Photograph by EW Greenwood. L. sousae is another Mexican species and rather unusual in that the column is somewhat more exposed. The lip of Lepanthes wraps around the column. Flowers are produced successively. Lepanthes escobariana is particularly striking with long stems of large golden orange flowers.

An excellent reference and key to Mexican species is Lepanthes en Mexico by Gerardo Salazar and Miguel Soto Arenas, Orquidea (Mex) Vol. 14, 1996. I was able to key the two Mexican species by comparing the diagramatic key with what I had in hand.

Octomeria (150 species)
Plants of this genus are variable in size and form. Flowers are unremarkable, often pale green, yellow to white, and produced in clusters from close to the juncture of the ramicaul and leaf petiole. Petals and sepals are similar in size and color. There are eight pollinia, a feature reflected in the generic epithet Octomeria (from the Greek word meaning ‘eight parts’). Octomeria decumbens bears a cluster of light yellow flowers with ruffled lips. The long narrow leaves are somewhat succulent.

Platystele (50 species)
If you are searching for the most charming pleurothallid in bloom. It could be a Platystele. The biggest thing about Platystele stenostachya is its name! The numerous tiny brownish gold flowers are borne successively on a branched raceme within the tuft of short-stemmed leaves. A hand lens reveals the distinctive hinged lip which on close examination is found to be densely pubescent. A perfect landing platform for some tiny insect pollinator.

Pleurothallis (some 2000 species)
This very large and variable genus contains both miniature and tall species. Flowers are produced singly or more often in clusters or racemes. Inflorescences sometimes arise from beneath a large heart-shaped leaf. In Pleurothallis cardiostolla, the showy reddish purple flowers form attractive clusters near the apex of a large elongated heart-shaped dark green leaf. The flowers of Pleurothallis truncata are produced as chains of tiny orange beads. New inflorescences can arise from the same leaf over its lifetime. Close examination of these flowers reveals that blooms remain open only a day or two during which time the column is exposed to pollinator visits.

Physosiphon
This subgenus is considered part of the genus Pleurothallis. Typically, there are many flowers on elongate racemes. Each flower is principally three showy sepals emerging from an inflated sheathing bract. Physosiphon tubatus has bright orange showy flowers.

Porroglossum (23 species)
The flowers of this intriguing genus have lips which when touched, spring shut, potentially trapping a pollinator against the column for a short period of time. The mechanism works something like what we find with the Sensitive Plant (Mimosa pudica). The leaf surface of Porroglossum species can be rough to the touch and the inflorescence may be densely pubescent. Porrovallia teagui has concolor rose pink flowers.

Scaphosepalum (25 species)
The non-resupinate flowers of this genus are borne successively along an extended inflorescence. They are distinctive in having long tailed sepals which extend outwards horizontally. Toward the end of each sepal is a raised patch or callus. Scaphosepalum grande has relatively large, brightly colored flowers in shades of yellow red and white.

Stelis (500 species)
The flowers of this genus are distinctively shaped so it is relatively easy to distinguish the genus but it is another matter entirely to reliably identify many of the species. The flat, triangular flowers are arranged in two rows. Colors range from pale green, bronze and pink, frequently with a contrasting center composed of the minute petals and column. Stelis mucronata is a Brazilian species with wine to greyish purple pubescent flowers borne on stiff reddish inflorescences which rise well above the leaves.

Trisetella (15 species)
This genus closely resembles Masdevallia. The three sepals are arranged such that the dorsal sepal opposes the synsepal which is composed of the other two parts. Trisetella huebneri is a showy representative of the genus.

Some useful references and links.

The Pleurothallid Alliance produces a quarterly newsletter packed with information. The website is a rich source of pictures, growing requirements and related material.

Icones Pleurothallidinarum is a series of technical references written by Dr. Carlyle Luer and published by the Missouri Botanical Garden. Number I deals with the Pleurothallidinae as an overview and is recommended. Number II presents an overview of Masdevallia systematics.

MarilyninOttawa
You have seen a range of pleurothallids. many can be a challenge to grow without coolness and high humidity but there are many also that manage quite well in a mixed collection.

Susan-from-Oregon
The Scaphosepalum verruscosa that I have is a rapid growing, ever-flowering WEED

MarilyninOttawa
Isn't that Physosiphon flower gorgeous?

Lynn O'Shaughnassy
I have a yellow form. http://www.pleurothallids.com/pleurothallis_tubata.htm

MarilyninOttawa
The yellow form much like yours Lynn, was the first one I ever saw. I remember Cordelia identifying it for me at a show. Thank you for showing us your example.

Susan-from-Oregon
The Stelis: THAT, I want!

Lynn O'Shaughnessy
Here is another Stelis http://www.pleurothallids.com/stelis_species_00285-00283.htm

Zeynep
Lynn, I like that one, have you been able to get it to identified, yet?

Lynn O'Shaughnessy
Not yet. I haven't had the time to go through the Stelis Icones. Even at that, Dr. Luer has many more new stelis to add

N_Calif_Kathy
Marilyn, all these are sooo small, how does one ever hybridize with them? Or even self them? You must have to tear the flower apart in order to use a 'toothpick. If even a toothpick is too large to accomplish that feat.

MarilyninOttawa
Good question. I use a sharpened toothpick or even a needle. Sometimes dissection is needed also. I usually examine a flower first to get an idea of the architecture then choose an appropriate tool.

N_Calif_Kathy
Probably using a sewing magnifier, too! I stand in awe.

Lynn O'Shaughnessy
I use a straight pin and a jewelers magnifying headband to pollinate

MarilyninOttawa
Choice of tools really depends upon the species/hybrid being pollinated. Some Masdevallias have relatively large pollinia and stigmas, easily seen with the naked eye. With smaller species, and especially if the pollinia are almost white and the column likewise, you have to use a jeweller's loupe (screws into the eye) or head magnifier. I manage with a hand lens. It is important that the pollination is done while the stigma is still sticky, ie, while the flowers are still fresh.

I have had a housefly captured within a flower of Masd. peristeria. The fly was caught between the thorax and the column. The lip held it pressed up against the column. When I pressed down on the lip, the fly backed out with pollinia attached to the thorax! You should have heard him...or her! The noise is what attracted me in the first place.

Ms.MacDuff,_Loyalton,_CA
I have a really simple, and embarassing question. When I pollinate Masd. Do I put the new pollen in the place where I remove the original sack?

MarilyninOttawa
The pollinia (pollen). There are two pollinia in Masdevallia. These are located under the anther cap at the tip of the column. Gently remove the cap. Sometimes the pollinia remain inside so take care. I do this over a white paper. The sticky stigmatic cavity is located just behind the anther cap on the undersurface of the column.

N_Calif_Kathy
What does one use as a flasking medium? I figured I'd ask since I sidetracked us into fertilization.

MarilyninOttawa
I have used various flasking media with success. I currently use Phytomax medium with 50 ml coconut water per liter added.

Lynn O'Shaughnessy
If you are looking for a pleurothallis (a large one at that) that is easy to grow and blooms with lots of flowers, try Pleurothallis gelida. The photo on the bottom had 440 inflorescences with an estimated 11,000 flowers. http://www.pleurothallids.com/pleurothallis_gelida.htm

Jade
Lynne, that is lovely and fragrant as well. A real winner. Does it need Cool or is Intermediate ok?

Lynn O'Shaughnessy
I find that it needs a bit of a cool down in the fall to set flowers, but it tolerates the higher temps in summer just fine.

N_Calif_Kathy
Wow, I could probably grow that one... I've been trying to grow some scaphosepalums. Just because the flower is so 'weird'. Having mixed luck - only because I'm not trying too hard to grow them. (I'm growing them in Cattleya conditions)

Susan-from-Oregon
And I've got Cattleyas growing in Scaphosepalum conditions.

Lynn O'Shaughnessy
Some scaphosepalums like it cooler, but they definitely benefit from higher humidity.

Lynn O'Shaughnessy
Another easy to grow pleurothallid genus is Restrepia. I don't think Marilyn mentioned it. My favorite is Restrepia muscifera as it looks like little clowns. http://www.pleurothallids.com/restrepia_muscifera.htm

MarilyninOttawa
I find on the easy list: Masd. tovarensis, Pleurothallis grobyi (give a cool snap for flowers
in a few weeks), Restrepias (as suggested by Lynne), Masd. nidifica, and Pleurothallis truncata.

Ms.MacDuff,_Loyalton,_CA
I have always wanted to grow a truncata(?)

Lynn O'Shaughnessy
Here is what they look like. http://www.pleurothallids.com/pleurothallis_truncata.htm

MarilyninOttawa
The challenge with pleurothallids is not so much growing them as flowering them. Many have flowers that will wither in dry conditions. It is always a challenge to photograph awarded certain pleurothallids before the flowers shrivel.

The Pleurothallis truncata flowers do not last long individually but as you see from the image kindly provided by Lynne, the flowers and inflorescences keep coming like the battery bunny. My plant started as a keiki and is blooming right now.

Lynn O'Shaughnessy
Here is M. tovarensis http://www.pleurothallids.com/masdevallia_tovarensis.htm

MarilyninOttawa
One aspect of orchids that intrigues me is the variation in populations. There can be quite a wide range of growing requirements, especially for species that are widespread in distribution. I have on warmth-tolerant and one not so warm-tolerant masd. tovarensis. I selfed and back crossed to see if the progeny will be more adaptable. So far, so good. This is one showy orchid.

Ms.MacDuff,_Loyalton,_CA
I have Masd. tovarensis. I will note that the one I bought was quite different than another one for sale, in flower size and quality.

Lynn O'Shaughnessy
There are many times that growing conditions affect the blooms. For example, look at this Masdevallia coccinea page. The flower on the far right was bloomed in the summer under warmer, drier conditions. The others bloomed in the winter. The one on the right blooms just like the others in the winter. http://www.pleurothallids.com/masdevallia_coccinea.htm

Ms.MacDuff,_Loyalton,_CA
Marilyn, here is another silly question. I got home from work before the chat, and just got to speed reae the pre handout. Explain to me, what exactly defines Pleurs. Are they miniatures?

Lynn O'Shaughnessy
They are not all miniatures. The P. gelida that you saw (bottom photo) is 2 feet across. I have some that are 2 to 3 feet tall.

Ms.MacDuff,_Loyalton,_CA
So, are they just a type like Cattleyas are a type? Can you cross them, the different types with each other?

MarilyninOttawa
Another good question! With such a huge and diverse group, there are bound to be some unsurmountable barriers to intergeneric hybridization. We do, however, have examples such as Dracuvallia (Dracula x Masdevallia) and Porrovallia (Porroglossum x Masdevallia). I recently attempted an intersectional cross of two Pleurothallis which was unsuccessful. You cannot really judge from just one attempt with only one plant of each species.

N_Calif_Kathy
What induces keiki formation? High tempertures like phals?

MarilyninOttawa
Good question Kathy. First of all, not all species produce keikis or offsets. Some, like Restrepia are very prolific producers. Much lies in the architecture of the plant and how it has evolved. Inflorescences are reproductive branches. The reproductive nature can be switched off (or not switched on) and what you get a another plantlet branch instead. In Phalaenopsis, we know that exposure of inflorescence buds to high temperature during development can render them capable only of producing vegetative offsets or keikis. This may or may not be happening with Pleurothallids. Someone needs to do the experiment!

Lynn O'Shaughnessy
Only some of the genera in pleurothallids will produce keikis. For instance, Masdevallias will not, and it seems that any others with leaves like Masdevallias will not. Restrepias, Zootrophions, Pleurothallis, Lepanthes, Lepanthopsis will. The common demonator in these last ones is they have a longer ramicaul with a leaf at the end. The Masdevallias (and others like them) have very short ramicauls that one does not even see as a "stem"

janetteh
Masdevallias are a mystery to me most of the time. We have a man here who grows mostly species. I have seen some plants from his gh that are pitiful looking. But then he brings a Masd. decumbens to a show that has four beautiful flowers. I don't know how he does it.

Lynn O'Shaughnessy
I have a friend of mine whose plants look like that also, but they flower. I find that I can't stand to see dried and brown leaves and am constantly grooming my plants to remove the ugliness. That is the one great thing about pleurothallids is that they multiply so fast that it doesn't take long to grow a good crop of leaves and remove the few ugly ones.

MarilyninOttawa
For those of you envious of my winter cold, I must tell you that it can also be too cold for may kinds of pleurothallid. Too hot or too cold, the result is the same. Stress for the plant, loss of foliage (the dreaded leaf drop) and possible loss of the plant.

My first Masdevallia was the Masd. nidifica which I definitely did not want as I expected it to die. It went on to grow up to specimen despite me.

Lynn O'Shaughnessy
M. nidifica comes in several colors http://www.pleurothallids.com/masdevallia_nidifica.htm

MarilyninOttawa
Thank you Lynne. I have the pale green form 'Bill's Gift', a red-striped and long-tailed form and an intermediate cream and red larger-flowered form. They do not seem to interbreed which is interesting.

jim4eq
I like that one so much I killed two of those, LOL. One I also love is norops

Lynn O'Shaughnessy
Here is norops http://www.pleurothallids.com/masdevallia_norops.htm

MarilyninOttawa
After visiting San Francisco a few years back, and seeing how the Masdevallias and some other pleurothallid genera were being grown outdoors, I decided to expose my plants to more sunlight. All my plants move outdoors in summer (May through October). They definitely respond positively to bright diffuse light provided humidity is high and there is good air movement.

Ms.MacDuff,_Loyalton,_CA
This is my unprofessional advice. Grow Madevallia like houseplants. Lots of water and keep them cool. If you are not comfortable in the temp, neither are they. I grow mine low to the ground in my house, near a little pond. I have a fogger on them....... not lots of misty drops. And, they seem to do okay..... 95 percent of them.

Zeynep
My orchids like to go outside during the spring and summer and part of the fall months.

Lynn O'Shaughnessy
I have no shade outdoors where I live. Besides, it is too difficult to take 3,000 plus plants outside. Hee hee

MarilyninOttawa
I use Reemay cloth over a wooden frame to provide 50-75% shade. I likewise have a large collection but they are miniatures and raised in trays so up the stairs I go in spring and back down again in autumn but do the plants thrive.

Susan-from-Oregon
Masd. barleana. I can't get mine to bloom. Grows well. Looks good, but no bloom.

MarilyninOttawa
In my experience, this is one that requires cold temperatures to bloom well. Grows well intermediate to warm however.

Lynn O'Shaughnessy
These are cool growers. My greenhouse gets to 50 at night in the winter. This is when they normally bloom http://www.pleurothallids.com/masdevallia_barleana.htm

Ms.MacDuff,_Loyalton,_CA
Mine is dropping to 55.

Susan-from-Oregon
There may be hope yet. I can supply cool. Thanks. I'll keep at it. (It actually had a spike last summer, which I broke off while watering)

Zeynep
What is your average day time high in the winter?

MarilyninOttawa
At this time of year, when it is very cold outdoors, the air intake for the furnace supplies a cold draft across the floor under the trays of Masdevallias in their artificially lighted home. Night temperature reaches 14°C. I was pleased to recently bloom Masd. harlequina. Several other species are triggered to flower by this natural cold draft.

Another aspect that is worth considering re: floweting triggers is day length. Some species are strong seasonal bloomers and this seems more a response to day length (long summer days vs short winter nights) than to temperature alone.

N_Calif_Kathy
So I take it the trick is to get these things identified, eh? It seems like there are always 'Pleur. spp' for sale at shows.

Lynn O'Shaughnessy
I have a large library and have it indexed as to where to find things. I have helped several people identify things from photos.

N_Calif_Kathy
As long as we covered flowering I can't recall if feeding was in the handout. I seem to recall very weakly

Lynn O'Shaughnessy
I use the MSU RO Special "miracle" fertilizer in a weak solution. It has done wonders for my plants and I use it exclusively.

MarilyninOttawa
Well folks, it has been a pleasure as always to discuss matters orchidaceous with you. Next week, I will be at the European Orchid Conference. Perhaps I will meet some of you there. Next month, I will be presenting on orchids whose names begin with A - Aerangis and Aerides. See you then. Goodnight!

Lynn O'Shaughnessy
Don't forget Acostaea

MarilyninOttawa
A special thank you to you Lynn O'Shaughnessy for your supplementary pictures and information. The Pleurothallid Alliance produces a quarterly newsletter packed with information. Your website is a rich source of pictures, growing requirements and related material. Congratulations!