Phoradendron macrophyllum (Engelm.) Cockerell, Amer. Naturalist 34: 293 (1900) (syn: Phoradendron cockerellii Trel.; Phoradendron coloradense Trel.; Phoradendron flavescens subsp. macrophyllum (Engelm.) A.E.Murray; Phoradendron flavescens var. macrophyllum Engelm.; Phoradendron leucarpum subsp. macrophyllum (Engelm.) J.R.Abbott & R.L.Thomps.; Phoradendron longispicum Trel.; Phoradendron longispicum var. cyclophyllum Trel.; Phoradendron macrophyllum var. circulare Trel.; Phoradendron macrophyllum f. glabrata Trel.; Phoradendron macrophyllum var. jonesii Trel.; Phoradendron serotinum subsp. macrophyllum (Engelm.) Kuijt; Phoradendron serotinum var. macrophyllum (Engelm.) M.C.Johnst.; Phoradendron tomentosum subsp. macrophyllum (Engelm.) Wiens; Phoradendron tomentosum var. macrophyllum (Engelm.) L.D.Benson);
Oregon to W. Texas and N. Mexico: Arizona, California, Mexico Northeast, New Mexico, Oregon, Texas as per POWO;

Shrub for ID : Fremont : 09SEP21 : AK – 005: 2 images.
While going through my California plants, I found some I had missed earlier.
Shrub, probably growing wild.

Pl. post high res. images to see the details.

2 high res. images.

This looks very like Loranthus europaeus but I am not aware if that grows in California. The nearest American genus is Phoradendron, I think. Unless you think your photo is of an introduced plant I would therefore suggest Phoradendron serotinum ssp. macrophyllum (Big Leaf Mistletoe) which is widespread in California as the most likely taxon.  It is on the Calflora website –





References: POWO  Catalogue of Life  The Plant List Ver.1.1  Tropicos  IPNI