I was asked recently the difference between Exhibition and Non-Exhibition Paphiopedilums, two classes in our monthly plant competition. I regularly get asked this question, so I will attempt to clarify the difference.
Firstly, what is a Paphiopedilum. This genus of about 60 species occurs from Southern India and southern China through south east Asia, New Guinea and Solomon Islands. Most Paphiopedilums are terrestrial, most growing in moist compost on the forest floor at moderate altitudes, but some are lithophytes growing in leaf litter on rocks or occasionally epiphytic. Paphiopedilums are easily identified from their common name Slipper Orchid as the pouch on the flower resembles the toe of a ladies slipper.
Now, back to the question at hand. Unfortunately, there is no strict definition of an Exhibition or Non-Exhibition Paphiopedilum. However, an Exhibition Paphiopedilum is distinguished by it large size and round shape from the smaller and more species like Non-Exhibition. Exhibition Paphiopedilum parentage generally contains a large number of crossings of a large number of Paphiopedilums species, whereas Non-Exhibition generally have a small number of crosses in their parentage. Therefore, Non-Exhibition Paphiopedilums are similar to species Paphiopedilums, whereas Exhibition Paphiopedilums contain a large number of parents to produce a very large round flower, unlike anything found in nature.
In practice, distinguishing Exhibition from Non-Exhibition is usually simple. Typical orchids in each class is shown below.
As you can see, the Exhibition Paphiopedilum is large (114mm across with this example which was TAPS orchid of the year in 1998) with very wide dorsal sepals and petals forming a virtually round flower. Paph. Global Harmony has 11 generations of breeding from 12 different species, whereas Paph. Hidden Surprise has 4 generations from four different species. Paph. Hidden Surprise is a much smaller species like Paphiopedilum, typical of a Non-Exhibition Paphiopedilum with much narrower dorsal sepal and petals than Exhibition Paphiopedilums, much closer to species Paphiopedilums. Armed with this information, there is now no excuse for not being able to separate Exhibition from non-Exhibition Paphiopedilums.
While we are discussing Paphiopedilums, did you ever wonder why such a small genus of orchids has such a dedicated following of growers? They even have their own club in Brisbane, TAPS, The Australian Paphiopedilum Society. No, it is not that they are particularly beautiful or easy or difficult to grow. It is because they cannot be mericloned. Most other orchid genus can be tissue cultured to produce thousands of identical copies of a prize winning plant in just a few years, but Paphiopedilums have defied all attempts to mericlone. Thus, all Paphiopedilums must be grown from seed or division keeping these orchids relatively expensive and slow to produce and making it possible for backyard growers to have every chance of producing valuable hybrids unlike other genuses with their proliferation of mericlones. Back yard breeding is what keeps the interest high in Paphiopedilums.