I've Eurpoean friends that have collected fish and plants all over Africa, and they told me that Anubias grow in areas that are submerged at times, and rather dry other times. I have grown a couple in terrariums with dart frogs, and they did fine.
I nifty trick I learned about anubias is if you nick the rhizome with a razor blade it will grow another "branch" on the rhizome. DO NOT BURY THE RHIZOME! Tie the plant in place until it attaches its self.
Try the auctions at Aquabid.com, there is usually a pretty good variety under the "Rooted Plant" section. I can remember the first one I saw 20 some years ago, it was A. nanus a friend got a piece of from Germany.

Hi
IMO they grow better emerged than submerged those large leaves are an algae magnet lol I place them in shallow water and let them emerge on their own..
The differences between the species is so small it's difficult to tell them apart. Barteri for the small leaf and coffeefolia for the large are the best in my opinion.
Unless your a botanist it really doesn't matter.
Some far more interesting families with this type growth are Microsorium and Cryptocorynes and of course Echinodorus.
Many different types with distinct differences,not to mention hybrids.
Almost any aquarium plant supplier will have Anubias
gary

Where can you find these, lucky you.... I love them, grow both well emerged or submerged. (emerged needs high humidity)

Low light, low maitenance (still needs ferts) add to water colume. here is a great site on education. (as you will find some types DO NOT do well submerged overtime. Some do great. What I like is his education on leaf identification as to what will and won't. I put them on driftwood, and am so happy with them. Only wish I could find what I'd like. Best Sherry

(sorry was blocked from posting site... please email me at sherryazure@yahoo.com and I will send site link. He is not an ad nor works for anyone, just russian guy who did much research on this species)

aquariumplants.com usually has a very good selection of aquatic plants - many of them anubias. I really like A. nana petite in my aquarium, but they might not be the right look for a stream. :)

Anubias have a rep as slow growing plants.Growing them emersed will show you how undeserved that rep is.

I just got a few "nanas" for my 5 gal. betta tank. I got mine from Mike's wet pets on ebay. Excellent plants!

Tom