I just saw this. If you are still looking here is what I found doing a search.

"Cardoon (Cynara cardunculus) is commonly used in Spain and Portugal as a vegetal rennet to coagulate sheep milk cheese. The following notes were obtained at Corfilac in Ragusa, Sicily at Cheese Art 2006 at a hands on demonstration workshop.

The part of the cardoon used to coagulate milk for cheesemaking is the lavender stamens that appear when the plant is in bloom. The stamens may be plucked or cut away from the base with a knife. The stamens should be dried at room temperature for about 3 weeks with periodic stirring to prevent mold growth. The dried stamens will keep for 2 years.

In a mortar and pestle or a blender grind the cardoon stamens to a powder. Suggested use rate is 1 gram of dried flower per liter of milk. The ground stamen should be steeped in room temperature water at the rate of 1 gram stamen to 10 ml water. Steep the mixture for 30 minutes. Strain through a paper filter before use. Add to the ripened milk at 30 C or 86F. i.e. 100 ml solution for 10 liters of milk. Coagulation should occur in 30- 45 minutes. Fresh flowers may also be used and the usage may be slightly reduced since the activity is stronger when fresh. This coagulant is more proteolytic and will produce a softer cheese.Proceed with the make procedure as desired."

Thanks Odduck, that is exactly what I was looking for.
I will harvest some stamens for use and let the rest dry off on the plant for seeds...funny, harvesting seeds from a "weed".