Sha Yuan (Astragalus chinensis)

Can you help me find the answers to a question I have regarding plant hardiness and identification?
I purchased seed of Sha Yuan (Astragalus chinensis) from Richters in '99. The catalog lists this as an annual. I grew it, but it didn't bloom that year, so I thought it would be gone in the spring (I live in zone 5). However, it returned in '00, obviously a perennial. It then bloomed, and set seed. For appearances sake, it looked just like Astragalus membranaceus (which I have grown previously, and am familiar with).
Is it possible that the seed I received was actually Astragalus membranaceus instead of the Astragalus chinenses that Sha Yuan is? Or is Sha Yuan a perennial, and not an annual?
Since I am an herb grower, and sell spring starts, I need to know which variety of astragalus I have!

According Lisa Xiaohong Li, our resident Chinese herbs specialist, reliable Chinese sources say that A. chinensis is perennial, not annual. The Richters catalogue description in the 2001 catalogue is wrong. It was based on erroneous data that were available to us when we first researched the plant. We will update our catalogue to reflect the change.
Chinese sources indicate that A. chinensis is very similar to A. membranaceus, with minor differences. A. chinensis has 6-10 flowers in each of raceme while A. membranaceus has 10-22 flowers. A. membranaceus flowers have a wing and keel with a long claw-like structure, but there is no mention if this is the same in A. chinensis. The seeds of the two species are very similar.