Orchid Anatomy Basics

Understanding orchids' basic anatomy and growth patterns will help you become a better grower. You'd be shocked how many questions we get asked and see online that can be helped by getting to know your plant. You don't need to be a taxonomist just to understand how your orchids grow, just a basic understanding will help you.

Let's start at the bottom.

Roots

I love sayings and there's a classic that is completely true; The amateur looks at the flower, the master looks at the roots.

The health of your plant starts with its roots. A poor root system does not allow for nutrient and water absorption (often caused by overwatering).

Healthy roots on most orchids should be white when dry, firm to the touch, and turn green when watered. When in active growth you should see green or reddish root tips. Unhealthy roots will be papery and soft or compress when touched. 

The white section after the tip is called velamen. This is a spongy epidermis that is in charge of water and nutrient absorption. It will turn green when it's healthy and freshly watered.  

Orchid roots do whatever they want to. They will grow out of their pots and attach to anything they can and overall have a mind of their own. Many orchid hobbyists are obsessed with roots and I'm one of them, often you'll see me post RPM or Root Porn Monday on my social media channels.

Rhizome

Not all orchids have rhizomes. Whether they do or do not depends on their growth pattern.

Some orchids have monopodial growth. Common ones are Phalaenopsis or Vandaceous orchids. These orchids grow upwards from a main stem or axis. The do produce keikis, a Hawaiian word for babies, asexually that can be propagated.

Orchids like Cattleyas and Oncidums have a sympodial growth habit. They create new plants in succession typically from the base of the first plant. They spread and grow outwardly with this habit. 

Rhizomes are a part of the stem at the base of the orchid that shoot out the new growth for sympodial orchids.

Sympodial orchids have our next term, pseudobulb.

Here's a great example from the AOS

 

Pseudobulbs

Sympodial growing orchids like; Cattleyas, Dendrobiums, Oncidiums, Bulbophyllums, and many more have pseudobulbs. 

They are storage devices for your orchid. Think of them like a camel's hump, storing water and nutrients for your orchids. Not all orchids have these, Vandaceous orchids are a great example of orchids without pseudobulbs. 

When pseudobulbs are present they should be full and not heavily wrinkled. When wrinkled they are being underwatered or they have a poor root system that can not intake enough moisture for your plant. When you get shipments of orchids in the mail they will most likely be wrinkled due to being dried out prior to shipping to avoid fungal issues but will plump again after one or two waterings. 

Think about the function of this part of your plant. If they have pseudobulbs that are storing water and nutrients would they need to be watered as often as an orchid that does not have them? The obvious answer is no. When to rewater is based on lots of additional factors; culture requirements, potting media, local environment, etc. Some orchids like Cattleyas want to dry out completely in between watering while Oncidium type orchids want to remain ever so slightly moist. Orchids without pseudobulbs typically like to be watered daily.

Leaves

As with the previous segments we're staying high level here. Why? Because there are way too many orchid types with variations. Some orchids are deciduous and lose their leaves seasonally. Some should never lose their leaves and only do so when stressed or unhealthy. Some orchids are leafless. A plethora of differences.

So what are some simple rules with orchid leaves we can all benefit by knowing?

First, while a deep green leaf is beautiful to look at it typically means that your plant is not getting enough sun. Yellow or white bleached spots means way too much sun, bleach spots are sunburned. Generally you want a nice light green color.

Second, leaf shape and type. Orchid leaves can be big, broad and flat, all the way to pencil shaped terete style. The variations are almost as endless as orchids themselves. With that said, usually the thinner the leaf the more sun it can tolerate. Most terete leaf orchids can be acclimated to full sun, move them slowly or they can still burn. While more broad flat leaves will want a slightly more shady location. Still be sure to check your specific plants culture requirements to be sure. 

Last, leaves should generally be smooth and somewhat firm. Leaves that are very soft/mushy, wrinkled, or with soft brown/black spots are signs of problems.

Conclusion

Thanks for reading! As we dive down this rabbit hole of orchids know that these are very general ideas and all orchids and the environments we grow in are different. Check with the vendor of any orchid you are purchasing for specific culture requirements.