What are orchids and what is so special about them?

Orchids are – currently with about 28.000 accepted species – the second biggest group of flowering plants worldwide.

This diversity and the wide distribution beg the question – how can you identify an orchid? The structure of the orchid flower is a key characteristic in identifying them. Orchid flowers are monosymmetrical. This means that both halves of the flower mirror each other. One special attribute of the orchid flower is that the female parts are fused to the so called column and the male parts are fused together to a pollinarium that sits protected under the anther cap. Three Sepals (outer circle of flower petals) and three Petals (inner circle of flower petals) form the flower. One of the petals differs greatly from the other two and forms the “lip” of the flower where pollinators can “land” on the flower.

Phalaenopsis violacea – Picture from C. Panhölzl

Orchids “steal, lie, cheat” and look impudently good while doing so.

Most flowering plants offer nectar to attract pollinators and reward them for their visit. Orchids on the other hand usually trick their pollinators into pollinating them and stick the pollinarium onto the animal without rewarding it for the visit. Some orchids evolved to look very similar as other flowers nearby so the pollinators can’t tell the difference. Others even look like female insects and even smell like them to trick the male insects into copulation and sticking the pollinarium onto the insects before they even realize that they got tricked.
Orchids also differ in their reproduction strategy and count on quantity before quality. Instead of producing few seeds with enough nutrient tissue to support the germinating seedlings orchids produce thousands and sometimes even millions of seeds per seed pod that are easily distributed by wind over a wide area. The downside is that very few of the seeds ever germinate.

Without the nutrients from the mother plant orchid seeds need help from the environment in form of special fungi in order to germinate. Some orchids have a symbiosis with these fungi and as soon as the orchid fully developed leaves it gives back nutrients to the fungus rewarding it for it’s initial help. Other orchids take advantage of the fungus for all of their life and force it to supply them with nutrients. Some orchid species even lost their ability to develop chlorophyll in their leaves and live as constant parasites of fungi or other plants.

This characteristic makes it peculiarly difficult to propagate rare orchids! Without the environmental fungi the seeds have to be grown on special nutrient media under sterile conditions in a laboratory. You can learn more about the propagation of orchids on the page orchidpropagation by seeds

Orchids conquered every environment on earth with the exception of the dry desserts and Antarctica and can be found all over the world. Also in Austria there are many terrestrial orchid species you can find in flower from spring to autumn on special places.

Orchis militaris in the national park Donau Auen in Vienna. Picture from C. Panhölzl

The most striking orchid species can be found in the tropical regions of the planet. Especially the discovery of the american continent lead to a proper orchid mania in the 19th century England. Wealthy orchid collectors financed elaborate and often dangerous expeditions deep into the unknown south american jungle in order to get their hands on new and exciting orchids never before seen by any human being. By far the most sought after orchids of the time were the big flowering species of the genus Cattleya. They were well regarded for their big flowers with often a very pleasing fragrance and collectors sold them for very high prices on regular orchid auctions at the time.

Cattleya mossiae in it’s natural habitat in Venezuela – Picture from M. Speckmaier

As you can see in the picture above, tropical orchids often grow directly on the trunk of big trees. Their roots do not grow into the tree to steal it’s water and nutrients but rather just use them to hold themselves on the bark. There exist other adaptations and you can find orchids growing in soil as well as directly on stones. However compared to the orchids found in Europe (all of them are terrestrial = growing in soil) most of the tropical orchids are so called epiphytes (= growing on trees) similar to the Cattleya mossiae in the picture.

It did not take long after the beginning of orchid growing in England that people also tried to cross different species of orchid with each other to create new and never seen hybrids with superior flowers or easier care. The close to endless possibilities for combinations lead to more than 100.000 registered hybrids of orchids whose popularity never ceases.

Picture from C. Panhölzl
Picture from C. Panhölzl
Picture from C. Panhölzl