Firm Brown Roots

[dianecty]

Hi! I have a question regarding roots.

When I trim the rotten roots off of an orchid, very often I see roots that are cream or brown. If I cut off the tip of this root, I see the thread inside. However, it is firm.

My question is, is this root rotten or not?

The reason I am asking is because I thought that rotten roots had to be soft and mushy. The one I am asking about is firm and yet it is brown or cream colored.

Thanks everyone!

[Dorothy]

Cream, brown and firm, I would consider, not rotten.
Black and mushy is rotten.

[Ross]

The fat part you are calling brown (or cream) is not the root. That is a coating the root uses to quickly absorb moisture and hold it till the root gets what it needs. The reason it is brown (or cream) has to do more with the age of the velamin (the coating) not the root. Normally for most orchids, the "roots" turn white when they are dry and green or brownish when they are flush with water. They are not rotten. And broken velamin is OK also. It still functions.

[dianecty]

Thanks! I didn't cut them off just to be sure.

[ipv6ready]

Hi I wonder if you clarify a little more.

What if the velamin is dark chocolate colour and wet but firm not mushy.

Are these roots one step away from rot?

[bodaciousbonsai]

If the roots are still quite firm and mot mushy they are still functioning properly.

[Ray]

Keep in mind that some of the organic materials used in potting media can release pigmented chemicals. Bark for example, can realease tannins, which are brown and water soluble. If the velamen absorbs the tinted liquid, it will appear brown.

I think it's also important to understand that an orchid root is not two-layered - velamen and central core - but is actually typically 6-layered.

Starting at the interior, we have the stele, which is the wiry core remaining in a dead root. Outside of that are the thin endodermis, cortex, exodermis and then velamen, which is simply dead exodermal cells that act as a sponge to store water.. The 6th "layer" is the root cap, which protects the root meristem at the tip.

This microscopic cross-section of an orchid aerial root shows the 5 distinct layers quite clearly. You'll note the velamen only accounts for about the outermost 20%:

[Gin]

I learned something new, Thank you for the info .
Gin

[kimstwin]

Thanks for posting that. I have never seen a diagram of a root like this. Interesting stuff.

[Cruetsonly]

My paphs are in shredded coconut fibers or bark. Their roots are chocolate brown and firm. They are growing quite nicely. The water, when it drains out the bottom, is also brownish. I agree that the media may be the source of the color of the roots. A firm root is a good root. When a root is dead, it is mushy.