Michael Moore has a nice write up in "Medicinal Plants of the Pacific West" where he sings the praises of Red Root for treating platelet aggregation. There is a list of constituents there as well as contraindications where he gives minor warnings for people on drugs related to blood clotting and people allergic to aspirin. Further, he does suggest not using Red Root if on medical care for an overt disease saying that Redroot is for healthy people who are stressed no sick folks under treatment.

This is from his website:

PLATELET AGGREGATION Platelets are the small, rather uniform fragments of
large bone marrow cells that aid the blood in coagulation, hemostasis,
inflammation, and thrombus formation. Mild subclotting and sticking is a
common early condition that can lead to thrombosis, atherosclerosis, and
strokes, and can be helped by an aspirin a day, better fat digestion, and
Ceanothus.

Also from Jim Dukes wonderful Plant Phytochemical Database Ceanothus is know to contain the following (more info in the database):

- BETULIN Root Bark: JAD

- BETULINIC-ACID Root Bark 200 ppm; PHYT13:2002 200 - 7,279 ppm JAD

Database:
www.ars-grin.gov/duke/

And yes, I would agree that very little is know of this amazing plant.

Good luck,

D