Drainage basin: The area drained by a river and its tributaries. A drainage basin is considered to be an open system because water can be added or lost from a drainage basin. Source: The beginning of a river. A river may have multiple sources.
Milk thistle (Silybum marianum) is a thorny plant presenting decorative leaves with a white pattern of veins and purple flower heads. The plant originates from mountains of the Mediterranean region, where it forms scrub on a rocky base.
This page looks at the use milk thistle on our dogs. Milk thistle is well known as a liver herb both for humans and pets. Milk thistle contains a flavonoid compound called silymarin which itself is a combination of several other active compounds.