Alec Baldwin and Kim Basinger's model daughter hit up the flea market in Studio City, CA Sunday and picked up some clothes and a few items for her pad, but most notably ... a cactus that appears to be around 7-feet tall.

Ireland enlisted the help of a burly guy friend to load the prickly plant into the back of a truck, which eventually made its way to her doorstep.

She shared a pic of her "new friend" on Instagram ... along with her cute little dog.

By the way ... we're told Ireland was at the flea market with her boyfriend, musician Corey Harper, and the helpful lad who helped her load the cactus is their pal, UK rapper Slang (aka Dan Dare).