A Mystery Orchid

This stopped me in my tracks. Flowering for the first time near the top a tree in the Tropical High Elevation House was an orchid I'd not noticed before. With its big solitary flower, it looked almost like an adolescent Pleurothallis gargantua. But the feeling that something was amiss sent me scurrying to the back up greenhouse for a ladder and then a closer look.

The handwritten label from Ecuagenera Nursery read 'Pleurothallis teaugei + gargantua.'  Odd. What did the plus sign mean? If Ecuagenera had created a hybrid, wouldn't they have labeled it with the names of the parents, separated by an 'x'? Is this plant a hybrid? Are teaguei and gargantua the parents?

Here's Pleurothallis gargantua, with its enormous solitary flower. For a quick guide to the floral parts, go here. The sepals look very much like those of our unknown orchid. But note that gargantua's rosy petals and yellow lip are very different.

And here's Pleurothallis teaguei flowering in the Tropical High Elevation House. If our unknown orchid is a hybrid, it could have inherited the rolled white petals from a teaguei. But where is it getting its rosy lip? Most likely not from gargantua or teaguei.

Flowering simultaneously was Pleurothallis marthae. With its rolled white petals and rosy lip, it appears to be a more likely contributor to the unknown orchid's genome.

But I can't be sure. The first step toward putting a name on this plant is to email a picture to Ecuagenera Nursery and ask for their data. Pleurothallid hybridization isn't exactly trending among commercial orchid growers, but I wouldn't be shocked if it were a hybrid. The larger Pleurothallids are fairly easy to pollinate. Alternatively, could this be a plant that Ecuagenera collected not in flower, and perhaps the names on the label were meant to be speculative? Could it be a species? There is nothing like it in Icones Pleurothallidinarum.

Whatever it is, our mystery Pleurothallis is a handsome plant. You can see it flowering now on the tree next to the door to the Conservation greenhouse.

The Frogs

The frogs are flowering. The "frogs" are a group of related orchid species within the vast subtribe Pleurothallidinae. (Acronia section Macrophyllae-Fasciculatae or Pleurothallis subsections Acroniae and Macrophyllae-Fasciculatae, depending on who you ask). The hooded sepals and spongy lip give the flowers the whimsical appearance of open-mouthed frogs. They are awesome.
  
What's inside those gaping mouths? Frog flowers can be baffling if you approach them with the expectation of seeing the conventional 3 + 3 arrangement of orchid petals and sepals. Here is a close up guide to a couple of the larger species, Pleurothallis gargantua and Pleurothallis marthae.

The dorsal sepal is usually erect and often concave. The lateral sepals are fused to form a synsepal. Lying opposite each other like the two halves of a clamshell, the dorsal sepal and synsepal give the flowers their mouth-like appearance. Pleurothallis gargantua (above) is a spectacular example and the largest of the frog Pleurothallids.

Pleurothallis marthae produces flowers that seem to remain half open. In the photo above, I've pulled back the dorsal sepal so you can see the interior of the flower from above. The column is short and the stigmatic surface is at its apex, not on the underside. The tiny anther has a detachable anther cap covering a minute pair of teardrop shaped pollinia.

Above, I've cut away part of the leaf of Pleurothallis marthae so you can get a closer look at the inflorescence. The inflorescence emerges near the apex of the ramicaul, a secondary stem that looks very much like a petiole. (The actual petiole is quite short and is separated from the ramicaul by an abscission layer.) The inflorescence is subtended by a sheath, called a spathe, that mostly obscures the peduncles. From the peduncles the solitary pedicels arise, each surrounded by a clear tubular bract, and emerge from the spathe. Among frog Pleurothallids, flowers are produced singly and one at a time (as in Pleurothallis gargantua), or singly and simultaneously (as in P. marthae).

The 'frogs' in the Tropical  High Elevation House are putting on an amazing show right now. Don't miss these terrific orchids!

Openings, Week of December 12

Pleurothallis gargantua in closeup. The flowers measure 1" across by 3" long.

Now is a great time to catch an amazing flush of flowers on the Pleurothallids in the Tropical High Elevation House.

Pleurothallis gargantua planted in the ground in the Tropical High Elevation House. 

Pleurothallis marthae can be grown as an epiphyte or as a terrestrial.

A yet-to-be-identified Pleurothallis growing epiphytically on a cedar tree

All of the Pleurothallids pictured above belong to my favorite section of the genus Pleurothallis, the Macrophyllae-fasciculatae, colloquially known as the clamshell Pleurothallids.

Not all Stelis are micro miniatures. This species produces flowers 1/2" diameter--huge for a Stelis.

I love it when the Pleurothallids steal the show!