Rushes the southern borders (6)

I believe the answer is:

sedges

I'm a little stuck... Click here to teach me more about this clue!

'rushes' is the definition.
The answer and definition can be both plants as well as being plural nouns.
Maybe you can see an association between them that I can't see?

'southern borders' is the wordplay.
'southern' becomes 's' (abbreviation).
'borders' becomes 'edges' (an edge is a border or margin).
's'+'edges'='SEDGES'

'the' acts as a link.

Can you help me to learn more?

(Other definitions for sedges that I've seen before include "Flies" , "Rush-like plants growing in wet places" .)

I've seen this clue in The Irish Independent.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.