As soon as I hit the "Submit" button, I realized I'd forgotten to add the species. Went to pending approval list, but couldn't seem to retrieve it.

Plant was approved, and I've since updated for approval again, but is there any way for the proposer to make changes once it's in the pending list?

Species was important in this case (even with cv) as it triggers custom fields for coleus

I'm afraid not. Once it's in the queue a moderator can click approve or decline at any moment and therefore it's not possible to let it be editable after the fact while awaiting moderation.

In such an event, the choices are to tree mail the moderator (or me) or else wait for the moderator to act on it and then submit a new proposal.

but that's normal. Does that mean the proposal is immediately shot to a moderator? It's not retrieved from the queue by the moderator? Just trying to understand...

The proposals wait in a queue for the moderator(s) to handle them. It's impossible for me to predict in software when a proposal might be handled by a moderator.

So if you could edit a proposal, it's possible that the events could occur like this:

1) User submits a proposal.

2) Moderator opens the proposal queue and starts contemplating the proposals.

3) Original user goes into the queue, finds their proposal, clicks on edit and starts making changes.

4) While #3 is happening, the moderator clicks on approve.

5) Then original user clicks "Save my edits" but it fails because the proposal was already approved.

I try to avoid these kinds of conditions, especially since the need to edit a proposal is hopefully extremely rare. I could find a solution that works some or most of the time, but, honestly, I have other things that have a higher priority since this issue is so infrequently a problem.

Thanks, understand now.