As for monkshood and wolfsbane, they are the same plant, which also goes by the name of aconite. Well? Why aren't you all copying that down?"
-- Severus Snape (PS8)
Aconite, also known as monkshood or wolfsbane, is a mundane plant with magical uses (PS8).
- Professor Snape lectures about aconite in Harry's first Potions Lesson (PS8).
- Aconite (as Wolfsbane) is used in the Wideye or Awakening Potion (Pm).
Potions Connection
Aconite is the "same plant" as Wolfsbane and monkshood, therefore it is used in the Wolfsbane Potion to help werewolves get through their monthly transformation without violence. As Wolfsbane it is an ingredient in the Wideye or Awakening Potion.
Commentary
Notes
In magical lore, aconite combined with belladonna was applied as a magical ointment by witches to make themselves fly. Aconite is an extremely poisonous plant (hence its other name of wolfsbane). It is also called monkshood because the shape of the flowers somewhat resembles a monk's cowl.
Scott Cunningham's Encyclopedia of Magical Herbs informs us that a folk name for the highly poisonous Wolf's Bane is "Dumbledore's Delight". -- SVA
Ellis Peters' medieval mystery 
Monk's Hood is recommended as both a very good story in its own right and as featuring both the positive and dangerous aspects of this plant. In the story the herbalist Brother Cadfael used the plant as part of an oil used to massage aching joints, but if swallowed or absorbed directly through any break in the skin, the oil could be deadly. -- MLW