Quiz 19: Can you name this medicinal herb?

A common weed found in the Ontario forest understory in early spring (hedgerows in the UK), pastures, meadows, river flats, roadsides and occassionally in lawns and gardens. Traditionally used as a strewing herb when houses had earthen floors, this herb would be scattered down on the ground to deter pests such as fleas, and to cover up unwanted smells with its slightly aromatic and sweet scent. There are several kinds of these perennials in Ontario, most of which have sticky leaves, and seeds which cling much like velcro. Because these plants were sweet smelling when dried (contains coumarin compounds which smell strongly of vanilla) they were often used to stuff straw mattresses. This compound also causes milk to curdle giving this plant the nickname “Cheese Rennet”. I would imagine it was once used in cheese making.

The roots can be harvested to yield a red to yellow dye depending on species but is not commercially viable due to the yield requirements.

Stones and urinary diseases, epilepsy, hysteria and nosebleeds are other noted uses for this herb. Bonus points for Latin name (genus)!