I have never grown Fennel.
Fennel is a very fragrant feathery-leaved plant that is often used as a garnish. It smells much like anise or licorice.
The full plant that you see here is in bloom. The base of the fennel plant has a large bulb that is above ground. These are available in food stores to be used in recipes.
As for the coming together of Catnip with Fennel, herbalists combine the two to benefit both the nervous system and the digestive system. The same properties that please cats are calming to the human body.
If you are not sensitive or allergic to either fennel or catnip, this can be soothing to spasms in the colon and intestines.
Some have used this combination for colic.
If you would like a fact sheet about this combination, please comment and request one, I will not post comments that contain requests...all comments are moderated.
If you have used Catnip and/or Fennel medicinally and would like to share your experience, please do share in a comment.
Image Credit: Catnip - Forest and Kim Starr - Wikimedia Commons
Fennel - Alvegaspar on Wikimedia Commons