January 23, 2014 | John Murgel, Horticulturist

Between now and February 24, the Orangery at Denver Botanic Gardens is hosting the annual Orchid Showcase. In addition to the blossom show being put on behind the glass walls of the collections greenhouses, the transitional space of the Orangery itself is festooned with orchids, mostly hybrids of the genus Phalaenopsis

Easily the most recognizable member of the vast orchid family for most Americans, Phalaenopsis orchids (also called moth orchids) hail from Southeast Asia, Oceana and Northern Australia. Only about 60 species populate the genus, but they have been hybridized into far more unique forms by specialty orchid growers. And why “moth orchids”? Karl Ludwig Blume, the man who “discovered” and named Phalaenopsis in 1825—almost 200 years after it was first named Angraecum album majus by a young Dutch East India Company Clerk named G. E. Rumphius—thought it looked like a moth. Phalaenops was a genus of moth (now defunct) named by Carolus Linnaeus (the father of modern taxonomy). Voila! Phalaenopsis, “thing that sort of looks like a moth,” was born!

 I think Blume must have been a squinter.  

Phalaenopsis violaceae

Nomenclature aside, the beauty and scarcity of orchids including Phalaenopsis made them a popular item for European plant collectors in the 18th and 19th centuries. Enterprising young men would sign contracts with nurseries and plant sellers to collect them in the far reaches of the globe.  The especially enterprising were able to denude entire forests of their orchids by cutting down the trees they grew on.  Relatively few of these plants made it back to Europe, though, as harsh conditions during shipping often killed them.  The discovery of the symbiotic relationship between fungi and orchid seedlings enabled growers to begin producing orchids in Europe and later on outdoor farms in the tropics.  But production of choice hybrids that would not come true from seed remained slow.

Because Phalaenopsis are monopodial (growing along only one axis and not regularly forming offshoots) they present a particular challenge to propagators.  Only if the growing tip is removed will most Phalaenopsis produce shoots from dormant buds at the base of the plant; this led bold growers to remove the top of their hybrids in hopes of producing more plants (at a rate of a few per year).  Beginning in 1949, though, experiments with hormone treatments and culturing sections of plants in vitro began to yield more profitable results.  By using micropropagation, the production of plants in special growth medium under aseptic conditions, several thousand orchids could be produced relatively quickly from a single mother plant; leading to the proliferation of inexpensive orchids available for sale at just about anywhere you can imagine, from the grocery store to roadside stands. Phalaenopsis are tolerant of a wide range of growing conditions (and generally enjoy the same temperatures as humans) so they are commonly offered for sale. 
Mounted Phalaenopsis
Usually seen growing in pots, Phalaenopsis are epiphytes in nature, clinging to trees and rocks with their wiry roots.  You may have noticed that their roots are whitish in color.  The roots are covered in velamen, a layer of dead cells that specialize in absorbing water from the air.  When misted with water, the cells become less opaque, allowing the green from the living cells below to shine through. Few homes in Colorado are humid enough to allow the casual growing of un-potted Phalaenopsis. If you have a window in a regularly used shower, though, you stand a chance of being able to keep a plant mounted on cork or another surface moist enough to thrive. A few orchids and maybe a touch of Spanish moss and each morning could begin with a tropical getaway! Learn more about keeping your orchids happy by visiting the Orchid Showcase on weekends—demonstrations by horticulturists from the “tropical team” begin at 12:30 on Saturdays and Sundays in Marnie’s Pavilion through February 23.



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