White Horehound is similar to its close cousin Black Horehound (Ballota nigra), apart from the flower colour and smell. This shrubby plant usually grows to approximately 45 cm. (1'- 2') in height, but has been found growing up to 91 cm. (3') tall, and has a musky smell when the leaves are bruised.
It should be treated with caution within the tortoise diet as in some animal studies White Horehound has been said to lower blood sugar levels and cause low blood pressure and abnormal heart rhythms.
We do not think that the odd nibble of a leaf will do any harm, as most of the toxic properties would only be felt if large quantities are consumed, but we advise you not to actively feed this plant.