The Strybing Arboretum lists is as cultivated variety of the Campbell Magnolia selected by the Arboretum back in the 30's from seed. Seed came in as Magnolia campbellii. However, they also mention that its likely the seed was the result of a hybrid cross.
This of course makes the naming a bit of a challenge. Since the name should be Magnolia 'Strybing White' without the specific epithet as the other parent is unknown and the hybrid not named and described. But it makes a much more exciting tree to be a white cultivar of a pink magnolia rather than some unknown cross resulting in a white flower.
Regardless, its a beautiful tree, and I love the green ting to the flowers and the large leaves. Growing upright with ascending primary branches it will likely be a large tree.
Leaves larger than other Campbell magnolias that I have seen, more elliptical and narrower at the tip. They reach 8-10" in length, are dark green with a distinct white lower surface that is really noticeable in the fall when the leaves are on the ground.
Flowers are large, 7-10" across, off white, cup shaped originally, but the outer tepals reflex, un saucer-like typically seen in the species. Inner most tepals are more white and larger than the outer tepals which have a green ting on the outside. Reproductive parts red. Fragrant. Blooms much earlier in the spring than other related species.
This one really stumped me.
Cabrillo College in front of the Sesnon House.