One very good English plant coming up, one with hollow leaves (7)

I believe the answer is:

isoetes

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'one very good english plant' is the definition.
The answer and definition can be both plants as well as being singular nouns.
Perhaps you can see a link between them that I can't see?

I don't understand the rest of the clue.

Can you help me to learn more?

(Another definition for isoetes that I've seen is " Quillwort".)

I've seen this clue in The Sunday Times and The Times.

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