The identification tag is the most widely used one on the site (as I write, there are 294 questions using it, and 200 for the next most popular, trees). However, many of them are little more than the question title and a sometimes blurry photograph of the plant (or even just of a small part of the plant).
I know that it can be difficult to describe a plant, especially if you don't know the botanical terms for things, but if you're curious enough about a plant to want us to identify it, there must have been something that piqued that curiosity; why not share that with us? There's a world of difference between "What is this plant?" and "What is this 2m tall shrub with spiky orange leaves?"
There are at least a few problems here:
for people answering, additional information is often needed to aid in identification: where the plant was found, size, shape, what the leaves/flowers/stems, etc. look like and so on.
answers often simply state the name of the plant; while technically correct, they are of little use without calling out the plant's unique characteristics so that people can learn. Care tips for the plant are often another useful addition.
for future people trying to identify plant X, there is no textual description of the plant, and photographs aren't searchable, so someone trying won't easily be able to find our Q&A about it.
I have some suggestions for how to improve this situation for our — and the site's — benefit, in no particular order (and indeed some of them not totally serious):
Write a FAQ (here on meta) for how to ask a good identification question, refer people to it and enforce the guidelines it contains.
The existing post here on meta doesn't provide that in a concise FAQ format, and while the identification wiki has some useful tips, it's not presented to someone asking a question: instead they have to go looking for it, assuming they even know it exists.
Write a FAQ for how to answer an identification question. Many answers simply state the name of the plant, where ideally the plant's identifying characteristics should be called out.
Ban identification questions outright; other Stack Exchange sites don't allow this type of question at all..
Quickly put any incoming questions on hold that lack enough textual information to provide an answer. My criterion here would be to imagine the question without the photograph; if you couldn't even begin to answer, then click “close” instead.
“What are you talking about? The identification questions are fine just the way they are.”
I'd like to hear what people think; either here or in the main site chatroom.