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Orchid Anatomy and Terminology

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orchid terminology anatomy

orchid anatomy and terminology

While learning about orchids are you coming across strange words like monopodial and sympodial? Then this article is for you. I don’t want there to be any confusion when it comes to orchid care and hope you find this glossary of orchid anatomy and terminology helpful.

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Orchid Anatomy

basic orchid flower anatomy

The orchid has three sepals, one dorsal sepal at the top and two lateral sepals one on each side. Three petals, one on each side and the lower lip, also called the labellum. The column and anther cap are the reproductive area of the flower.

Orchid Terminology

Aerial Roots

Aerial roots are roots that do not grow down into potting media, but rather, grow out into the air. These roots are specifically designed to grow in air and should not be potted or worse, cut off. 

Aerial roots - orchid anatomy

Aerial roots grow in the air, as opposed to down in the potting mix. Resist the temptation to trim away aerial roots as they absorb water and assist the orchid in photosynthesis.

 

Bilateral Symmetry

Have you ever felt like your orchid was looking at you? Perhaps it’s because they look like our faces–well, sort of. Our faces and orchid flowers are both bilaterally symmetrical. This means that if you divide our face, and orchid’s face, in half, from top to bottom, one side would mirror the other. Most other flowers have radial symmetry, the faces of these flowers can be sliced in any direction and still mirror each other.

bilateral symmetry - orchid anatomy

Doesn’t it almost seem like this orchid can see you?

 

Bud Blast

If you’ve had seemingly healthy bud wither up and die for no apparent reason you have first-hand experience with bud blast. Though deeply disappointing, bud blast can be avoided once you know its causes. Bud blast is the result of drastic environmental changes. Changes in temperature and watering fluctuations common causes of bud blast. Pollution also causes bud blast.

To decrease the chances that your orchid experiences bud blast, keep your orchid away from heating and cooling vents, drafts from a frequently used exterior door and riding in the trunk of the car. If you grow your orchids in one room of your house and then bring them out to the main living space when they are in bloom, it is a good idea to let all the flowers open before moving the orchid.

Bud Blast - orchids

When seemingly healthy buds wither and die without blooming it’s called bud blast. It’s caused by environmental changes like temperature and water fluctuation. The good news is that it’s preventable.

 

Inflorescence

The inflorescence of the orchid includes more than just the flower. Inflorescence includes the full flower stalk and all the flowers and buds growing on the stalk. 

Cattleya - orchid anatomy

The inflorescence includes the whole flower spike or stems where the flowers emerge. After flowering, the flower stalk is cut to help prepare the orchid to bloom again.

 

Keiki

Keiki means baby in Hawaiian and refers to a plantlet growing off the mother orchid. A keiki is an exact clone of the mother plant. If the keiki grows its own roots, the keiki may be removed when the roots are several inches long and potted up. 

If the keiki does not have its own roots it is called a basal keiki. Basal keikis grow at the base of the orchid. As a basal keiki does not have its own root system it is dependent on the mother plant for its nutrients and should not be separated from the mother plant. 

keiki - orchid terminology

Keiki means baby in Hawaiian and refers to a new orchid growing from the mother orchid. When the roots and leaves are a few inches long, they can be separated from the mother plant.

 

Kokedama

Kokedama means moss ball in Japanese and is a Japanese form of growing plants. Wrap the roots in sphagnum moss to grow your own orchids kokedama style. I have had a lot of success and fun growing Phalaenopsis orchids this way.

kokedama orchid in bloom

For a tutorial that will walk you through potting your own orchid kokedama style, click here.

 

Monopodial

Phalaenopsis and vanda orchids are both examples of monopodial orchids. Monopodial orchids grow from a single stem and not along a rhizome. These orchids do not have water storage in the form of pseudobulbs. 

monopodial orchid - orchid anatomy

Monopodial orchids such as a Phalaenopsis or a Vanda have a single vertical stem. Leaves grow out of the stem and roots emerge from the base of lower leaves. Flower stalks grow from the base of new leaves.

 

Orchid Seed Capsule

Orchids seeds are a fascinating subject and were a puzzle for many years as scientists struggled to discover how to grow orchids by seeds. Eventually, scientists learned that orchid seeds need certain types of fungi to infect the seeds. The orchid seeds are then able to draw nutrients from the fungi and the seed will begin to swell and grow.

Orchid seeds are so extremely small that one seed capsule can contain tens of thousands of minuscule seeds. If a seed lands in a hospitable growing area, complete with the right fungus, the seed may mature and grow. 

In nature, it can take several years for the seed to grow a root system substantial enough to become a seedling and poke up through its protective covering (moss, etc). 

Orchid seed pod - submitted by Karina

Thank you, Karina for submitting this photo of your orchid seed capsule.

 

Sheath

Sheaths are a papery layer that covers pseudobulbs. Sometimes pests, such as scale, like to hide in sheaths. To dress up your orchid for display, or to check for bugs, carefully remove the sheaths. 

Sheath papery tissue

A sheath is a papery tissue that covers a pseudobulb as on this Cattleya.

 

Stomata

Stomata are pores on the orchids’ leaves that allow them to absorb carbon dioxide and expel oxygen. When stomata open water escapes out through the pores. To keep the orchid from dehydrating, water in the air, humidity makes up the difference. When there is not enough humidity, the stomata close and the orchid does not absorb the carbon dioxide it needs. 

 

Sympodial

Most orchids are sympodial, meaning that they grow along a rhizome and have pseudobulbs. You can learn a lot about an orchid by its pseudobulbs. The newest pseudobulb is called the lead bulb and should be plump, stiff and larger than older pseudobulbs. When the orchid reaches maturity, the pseudobulb will be the same size as the previous year’s bulbs. Older bulbs are called back bulbs.

Sympodial orchids are a good investment if you want to grow your orchid collection. Sympodial orchids can be divided when potting. Just be sure that each division has about 4-5 pseudobulbs.

sympodial orchid - orchid anatomy

Sympodial orchids grow from a horizontal rhizome off of which grow pseudobulbs. Backbulbs refer to older pseudobulbs, while lead bulbs are new pseudobulbs from which new growth appears. New growth is where new pseudobulbs and flower stalks will form. Although backbulbs may not produce flowers, they still perform an important function for the orchid: water storage.

 

Transpiration 

Transpiration is the rate of water loss when leaves open their stomata (pores) to absorb carbon dioxide and expel oxygen. If transpiration rates are too low the orchid stops breathing.

orchid terminology - transpiration

Adequate humidity is essential for a well-hydrated orchid. Transpiration is the rate of water loss when leaves open their stomata (pores) to absorb carbon dioxide and expel oxygen.

To successfully grow orchids indoors, there’s nothing like a humidifier to grow healthy orchids.  To prevent damage to your home, keep humidity around 40-50%. To prevent damage to your home, I recommend using a humidistat. Within this 40-50% maximum humidity range there are many orchids that will do very well.

For growing orchids indoors, look for orchids such as:

Unless you can provide a high humid environment, avoid growing indoors high humidity orchids such as:

  • Draculas
  • Masdevallias
 

Velamen

Velamen is a sponge-like tissue that absorbs water and nutrients and covers orchid roots. Velamen only absorbs water – it doesn’t release it – that’s why it’s important not to overwater your orchids. 

Velamen is stiff and firm when healthy, but turns limp if it gets too much water. If the orchid is underwatered the velamen turns brown and brittle. 

orchid anatomy - orchid roots

Velamen acts as a sponge, absorbing water and nutrients. It covers orchid roots just behind the green tips and absorbs water and nutrients. The green tips of this Cattleya orchid indicate a healthy, actively growing orchid.

 

I’m Here to Help

If you ever come across an unfamiliar word or phrase when learning more about caring for orchids, don’t hesitate to leave a comment below. This archive of orchid anatomy and terminology is a work in progress.

8 Comments
  1. Judy says:

    I came across a beautiful orchid plant, never seen it bloom. But seems to have a healthy root system. The velium ( I think) are about 5 inches long and there’s 4 of them. How can I persuade this plant to bloom?

    1. Anna says:

      Judy,
      This is exciting! The first thing to do is to find out what kind of orchid you have. Light and temperature are the two main factors that contribute to blooming. Some orchids, like cattleyas, need a lot of light to bloom, while others like phalaenopsis don’t require as much light. Many orchids need cooler temperatures to trigger blooming – but again, how low and for how long depends on the orchid. Also, keep in mind that a young orchid will need to mature before blooming. Will you send me a picture of your orchid and I’ll see if I can identify the orchid? Email me at [email protected].

  2. Katy says:

    Dear Anna I love your site and also uour helpful hints that I adapt for my North Queensland Australia weather- humidity city lol. I currently have 64 orchids all varieties- Vanda, Cattleyas, Oncidiums, Phalaenopsis they all keep me busy. Really like your orchids and terminology 101. I had a problem like everyone else accessing this so glad it was fixed. I often have a hard time accessing your care cards as well. Hit and miss unfortunately.
    Thanks
    Katy

    1. Anna says:

      Katy,
      Thanks for reaching out to me. I really appreciate your feedback. If you have a minute will you email me, [email protected], and let me know what the problems have been accessing the orchid care cards? Hopefully, this way I can fix whatever the problem is.

      You are living in the perfect city to grow lots of beautiful orchids!!
      Thanks again,
      Anna

  3. Liz says:

    I have a lovely orchid plant at work (private home) that have kept alive since January hoping it would rebloom. Turns out what I thought were buds are actually new plants. HELP!!! I have no clue what I am doing 🤣

    1. Anna says:

      Liz,
      These little plantlets are called keikis and are exact clones of the mother plant. When the roots and leaves are about 3-inches long you can remove them from the mother plant by making a cut (with sterilized scissors) on either side the keiki where it is connected to the mother plant – leave a couple of inches of flower stalk on both sides of the keiki. You can then pot up the keiki. Another option is to do nothing and just let the keiki grow as-is – connected to the mother plant. If you do decide to remove the keiki, know that the longer you keep it attached to the mother plant, the better its chance of survival.

  4. Myrline says:

    Dear Anna
    I have a phaleanopsis which is blooming but the leaves are decaying at the same time.. Don’t know what to do.. Can you give me some tips.

    1. Anna says:

      Myrline,
      While the flowers are awesome, the decaying leaves are a bummer!

      Here is an article that will help you identify and treat orchid pests and disease:

      ORCHID PESTS AND DISEASE

      If you don’t can’t figure out what is going on with your orchid’s leaves, email me at [email protected]. Be sure to include photos.
      Wishing you all the best,
      Anna

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START HERE to Learn How Grow Healthy Orchids!

Care for your orchids with confidence.

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