[orhunterfisher]

I never remove them, they pretty much go away on their own. After a few months, the main stem is about all that's left.

+1 Rock.
If they are from a good trustworthy source, they can be immed. dropped in and left until they degrade completely. You can have as many as 4-6 per 20 gallon tank depending on their size. Some are huge and others are smaller.