Possible Clues:

• Work rejected, I see, in terribly noisy, hazardous plant
• Plant responsible for much itching
• Irritating growth
• Irritating vine
• Subject of the saying 'Leaves of three, let it be'
• Mango's allergenic relative
• Romantic interest of Harley Quinn
• If you're rash enough to touch the climber, it leads to a rash result