Pneumathodes?

[wirtlo]

Hi all. I didn't realize this 'science matters' forum was on here (pretty cool!), and I think its the perfect place to ask my question:

What are the white dots on orchid roots called (I've seen them on Angraecums, Phalaenopsis, and Dendrophylax)? I was curious as to their function, but I have to know what they're called before I can find that. The only thing I could find was a 1957 Dycus and Knudson article that mentioned them as "pneumathodes," and that didn't bring up much in a search.

Is there another name they go by? Or do you know what they do?

Thanks!