What is "notholithocarpus"

Notholithocarpus densiflorus, commonly known as the tanoak or tanbark-oak, is an evergreen tree in the beech family ( Fagaceae), native to the western United States, in California as far south as the Transverse Ranges, north to southwest Oregon, and east in the Sierra Nevada. It can reach tall (though is more usual) in the California Coast Ranges, and can have a trunk diameter of .

Tanbark-oak was recently moved into a new genus, Notholithocarpus (from Lithocarpus), based on multiple lines of evidence. It is most closely related to the north temperate oaks, Quercus, and not as closely related to the Asian tropical stone oaks, Lithocarpus (where it was previously placed), but instead is an example of convergent morphological evolution.