Epiphytic orchids, those that grow upon a support, have modified aerial roots that can sometimes be a few meters long. In the older parts of the roots, a modified spongy epidermis, called a velamen, has the function of absorbing humidity. It is made of dead cells and can have a silvery-grey, white or brown appearance. In some orchids, the velamen includes spongy and fibrous bodies near the passage cells, called tilosomes.
Sympodial: Sympodial orchids have a front (the newest growth) and a back (the oldest growth).[5] The plant produces a series of adjacent shoots, which grow to a certain size, bloom and then stop growing and are replaced. Sympodial orchids grow laterally rather than vertically, following the surface of their support. The growth continues by development of new leads, with their own leaves and roots, sprouting from or next to those of the previous year, as in Cattleya. While a new lead is developing, the rhizome may start its growth again from a so-called 'eye', an undeveloped bud, thereby branching. Sympodial orchids may have visible pseudobulbs joined by a rhizome, which creeps along the top or just beneath the soil.
The orchid family is an incredibly large and diverse plant family, with more than 25,000 different species and more than 150,000 registered hybrids. The variation within a single species can be significant, let alone across the entire family. But with a little practice, knowledge, and observation, almost anyone can identify the most common types of orchids. Identifying one orchid from the next will be helpful in understanding what conditions they prefer and how to grow and flower them well. Happy growing!

Masdevallia is one of my favorite types of orchids! They have triangular flowers (the petals are tiny, so you just see the three sepals.) They need cool temperatures to do well, and like a lot of humidity, but are otherwise quite easy to grow. (But they have a reputation as being hard to grow from people who've ignored their temperature and humidity requirements.)
The term "botanical orchid" loosely denotes those small-flowered, tropical orchids belonging to several genera that do not fit into the "florist" orchid category. A few of these genera contain enormous numbers of species. Some, such as Pleurothallis and Bulbophyllum, contain approximately 1700 and 2000 species, respectively, and are often extremely vegetatively diverse. The primary use of the term is among orchid hobbyists wishing to describe unusual species they grow, though it is also used to distinguish naturally occurring orchid species from horticulturally created hybrids.
Brassia, Comparettia, Odontoglossum, Polystachya, Cochleanthes, Tolumnia, Trichocentrum, Brassavola, Psychilis CC Image courtesy of Arne and Bent Larsen on Wikimedia Commons  |  Catasetum, Cymbidium CC Image courtesy of http://www.larsen-twins.dk on Wikimedia Commons  |  Cephalanthera CC Image courtesy of Sramey on Wikimedia Commons  |  Dichaea, Eulophia, Galeandra, Trichoglottis, Lycaste, Stanhopea, Caularthron, Domingoa, Prosthechea, Dendrobium, Goodyera, Stenorrhynchos, Pogonia, Gymnadenia CC Image courtesy of Orchi on Wikimedia Commons  |  Dipodium CC Image courtesy of David Lochlin on Flickr  |  Ionopsis, Campylocentrum CC Image courtesy of Maarten Sepp on Flickr  |  Macradenia CC Image courtesy of Maarten Sepp on Flickr  |  Koellensteinia CC Image courtesy of Alex Popovkin on Flickr  |  Leochilus CC Image courtesy of Marcos Antonio Campacci on Wikimedia Commons  |  Oeceoclades, Bletia, Chiloschista, Renanthera, Miltonia, Brachionidium, Cattleya, Lepanthopsis, Nidema, Scaphyglottis, Trichosalpinx, Eria, Coelogyne, Cyclopogon, Eltroplectris, Eurystyles, Platythelys, Prescottia, Psilochilus, Triphora, Paphiopedilum CC Image courtesy of Dalton Holland Baptista on Wikimedia Commons  |  Oncidium CC Image courtesy of Calyponte on Wikimedia Commons  |  Arethusa CC Image courtesy of Chris Meloche on Wikimedia Commons  |  Arundina CC Image courtesy of Kevin Gepford on Wikimedia Commons  |  Calopogon CC Image courtesy of Bob Peterson on Flickr  |  Cleisostoma CC Image courtesy of Earth100 on Wikimedia Commons  |  Dendrophylax CC Image courtesy of Mick Fournier on Wikimedia Commons and CC Image courtesy of Big Cypress National Preserve on Flickr  |  Micropera, Crepidium CC Image courtesy of Raabbustamante on Wikimedia Commons  |  Taeniophyllum CC Image courtesy of Airborne Pilot on Flickr  |  Corallorhiza CC Image courtesy of Wsiegmund on Wikimedia Commons  |  Maxillaria CC Image courtesy of Walter on Flickr  |  Govenia CC Image courtesy of Sanfelipe on Wikimedia Commons  |  Isochilus CC Image courtesy of Patricia Harding on Wikimedia Commons  |  Lepanthes CC Image courtesy of Quimbaya on Flickr  |  Elleanthus CC Image courtesy of Philipp Weigell on Wikimedia Commons  |  Pleurothallis CC Image courtesy of KENPEI on Wikimedia Commons  |  Restrepiella CC Image courtesy of Moises Béhar on Wikimedia Commons  |  Bulbophyllum CC Image courtesy of Montrealais on Wikimedia Commons Calanthe CC Image courtesy of Qwert1234 on Wikimedia Commons  |  Phaius CC Image courtesy of Hectonichus on Wikimedia Commons  |  Spathoglottis CC Image courtesy of Vaikoovery on Wikimedia Commons  |  Calypso CC Image courtesy of Walter Siegmund on Wikimedia Commons  |  Tipularia CC Image courtesy of TheAlphaWolf on Wikimedia Commons  |  Malaxis CC Image courtesy of Bernd Haynold on Wikimedia Commons  |  Oberonia CC Image courtesy of Ramesh Meda on Flickr  |  Anoectochilus CC Image courtesy of Badlydrawnboy22 on Wikimedia Commons  |  Cranichis CC Image courtesy of Americo Docha Neto on Wikimedia Commons  |  Mesadenus, Pteroglossaspis CC Image courtesy of NC Orchid on Flickr  |  Pelexia CC Image courtesy of Elena Gaillard on Wikimedia Commons Ponthieva CC Image courtesy of Jose Lacruz on Wikimedia Commons  |  Spiranthes CC Image courtesy of Eric in SF on Wikimedia Commons  |  Zeuxine CC Image courtesy of Panoso on Wikimedia Commons Dactylorhiza CC Image courtesy of Uoaei1 on Wikimedia Commons  |  Habenaria CC Image courtesy of J.M.Garg on Wikimedia Commons  |  Ophrys, Pseudorchis CC Image courtesy of Hans Hillewaert on Wikimedia Commons  |  Orchis CC Image courtesy of Algirdas on Wikimedia Commons  |  Platanthera CC Image courtesy of Enrico Blasutto on Wikimedia Commons  |  Epipactis CC Image courtesy of Dcrjsr on Wikimedia Commons  |  Listera CC Image courtesy of Superior National Forest on Flickr  |  Sobralia CC Image courtesy of João Medeiros on Flickr  |  Broughtonia CC Image courtesy of Walter on Flickr Masdevallia CC Image courtesy of trixty on Flickr  |  Isotria CC Image courtesy of Jason Hollinger on Flickr  |  Flickingeria CC Image courtesy of Averater on Wikimedia Commons  |  Cleistesiopsis CC Image courtesy of Charly Lewisw on Wikimedia Commons  |  Cypripedium montanum CC Image courtesy of Bill Bouton on Flickr  |  Cypripedium reginae CC Image courtesy of Orchi on Wikimedia Commons  |  Disperis, Encyclia, Epidendrum, Vanilla planifolia, Vanilla barbellata CC Image courtesy of Malcolm Manners on Flickr  |  Govenia CC Image courtesy of Bosque Village on Flickr  |  Psychopsis CC Image courtesy of LadyDragonflyCC – >;< on Flickr  |  Aplectrum CC Image courtesy of Fritz Flohr Reynolds on Flickr
The main characteristic of this type of orchid is its very pleasant aroma, which means you will likely smell it even before you see it. The pure white flowers release their scent at night, are frequent bloomers, and can bloom all year long in many places. They are a small but showy type of orchid, and their leaves are long, reed-like in shape, and light green in color. They are also easy to grow and are low-maintenance flowers.
The Cypripedioideae subfamily is known for its lady slipper orchids, which are named after their slipper-shaped pouches that trap insects and help the flowers get pollinated. There are 5 genera in this subfamily: Cypripedium, Mexipedium, Paphiopedilum, Phragmipedium, and Selenipedium. Cypripedioideae orchids have two lateral, fertile anthers, which is unusual in most other orchids.
Phalaenopsis, the Moth Orchid, is one of the most commonly available and easiest to grow orchid genera. It is an especially good choice for beginners to orchid growing. They have large, showy flowers that come in a wide variety of colors. Most species have several flowers per stem, but some have more, and others have as few as one or two. There are a great many hybrid varieties on the market.
There are over 60 varieties of the Vanilla orchid, and unfortunately, it only blooms for one day, opening in the morning and closing at night. They grow in clusters of 12-20 buds, and they are yellow-green in color and reach approximately six inches in length. Just like their name suggests, you can actually get vanilla from these flowers, and the blooms have a nice vanilla scent as well. They have to be mature in order to flower, which can take two to three years, and they grow up to ten feet in height. They do best in a garden or a greenhouse, but never as an indoor plant, and they need vertical support to grow and thrive.
Orchids have many associations with symbolic values. For example, the orchid is the City Flower of Shaoxing, China. Cattleya mossiae is the national Venezuelan flower, while Cattleya trianae is the national flower of Colombia. Vanda 'Miss Joaquim' is the national flower of Singapore, Guarianthe skinneri is the national flower of Costa Rica and Rhyncholaelia digbyana is the national flower of Honduras.[29] Prosthechea cochleata is the national flower of Belize, where it is known as the black orchid.[30] Lycaste skinneri has a white variety (alba) that is the national flower of Guatemala, commonly known as Monja Blanca (White Nun). Panama's national flower is the Holy Ghost orchid (Peristeria elata), or 'the flor del Espiritu Santo'. Rhynchostylis retusa is the state flower of the Indian state of Assam where it is known as Kopou Phul.[31]
The vast majority of orchids grown in the home are epiphytes, meaning they live in nature by clinging to trees or even stones. The roots of these plants are highly specialized organs that differ dramatically from normal plant roots. Of course, it's hard to generalize about anything when it comes to orchids. This is the single largest group of plants in the world, so for every rule, there are 100 exceptions.

Another type of orchid you can grow at home is what I call the “Thai restaurant orchids.” These types of orchids are Dendrobium hybrids and can be found at Thai restaurants that decorate their tables with freshly-cut flowers. They come in many colors (white, green, purple, pink, yellow and more) and require a fairly warm environment. In fact, they could loose their leaves in the winter when the ambient temperature drops below 60°F (15°C) or so. But the “Thai restaurant orchid” is really just one small group of hybrids within the Dendrobium genus. Dendrobium is actually one of the largest orchid genera.
The Bulbophyllum orchid genus is the largest in the Orchidaceae family, with over 1800 species, making it the third largest genus of plants. (Taxonomists will probably eventually split it into several smaller genera, but with so many types of orchids it's a massive undertaking!) They differ widely in appearance, but all have a single leaf emerging from the top of the pseudobulb, flower stems coming from the bottom of the pseudobulb, and a hinged lip designed to tip insects against the column. Many are pollinated by flies, and stink like dung or rotting carcasses, which is a great conversation starter and gives you bragging rights for putting up with it! (They don't all stink, fortunately.) The rhizomes wander all over the place and often branch freely, so it's easy to grow an impressive specimen.
Also called Cockleshell orchids, they have no fragrance, but they do bloom for several consecutive months, making them appealing for people who want color in their garden for long periods of time. The Encyclia orchid has dangling petals and sepals, which is why some people say it resembles an octopus. It thrives when planted on an orchid mount because this simulates the epiphytic growing conditions found in the wild, and it comes in colors such as yellow-white with purple throats at the top.
The Lycaste orchid genus, similarly to its relative Anguloa, likes intermediate-to-bright light, intermediate-to-cool temperatures, and high humidity. The flowers look rather different, though; they are more-or-less triangular in shape because the sepals point outward while the petals point forward. These orchids are very fun to grow, and will thrive if you get their care right.
The orchid plant is also unique in its morphology (form or structure). We can begin with the leaves and work our way down to the roots. The leaves of many orchids in cultivation are unique in that they are specifically designed for water conservation (as is true for almost every orchid structure). They have a heavy waxy leaf coating and specialized stomata (openings through which the leaf “breathes”) that help to prevent water loss during transpiration (the act of the plant “breathing”). Many orchids utilize CAM photosynthesis as well, which in essence means that the plants collect materials during the day and then process them at night.
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