The Mimbulus mimbletonia is a very rare magical plant from Assyria. It is said to resemble a grey cactus, but instead of spines, it had boils. When poked, these boils squirted Stinksap as a self-defence mechanism. Although not poisonous, the liquid was said to smell foul.

The plant is also said to be rather squirmy, and prefers high temperatures and light with low moisture to thrive. During the growth stages, it was noted to make crooning noises. When "flowering", it released a strong odour and the boils formed which was the sign it was ready to be harvested. The boils hd to be removed carefully to avoid bursting, but they could be used in potion-making.

Neville received one of these plants for his 15th birthday from his Uncle Algie, which he brought to school with him.