Handirifle,
Sorry so long. I am just about to post another doe I just got this am and noticed your question on this thread.
ERC is Eastern Red Cedar. It's shorthand that is pretty common on here, rather than typing out the whole name. Laziness on our part.
Anyway, it's really pretty, good quality bow wood, if kind of tempermental. Actually a juniper, it's pretty light and elastic, and makes a really fine and attractive bow.