Flora of North America species comparison

The difficulty in distinguishing Texas populations of Quercus fusiformis from Q. virginiana is reflected in a variety of taxonomic treatments, including reducing Q. fusiformis to varietal rank under Q. virginiana. The latter disposition is problematic, however, because Q. fusiformis in northeastern Mexico is amply distinct from Q. virginiana and appears to be more closely related to Q. brandegei Goldmann, an endemic of Baja California, Mexico. Thus, here we assume that the intergradation of Q. virginiana and Q. fusiformis is a result of secondary contact, and is not primary clinal variation. Under this interpretation, Q. virginiana in typical form extends into Texas only as far west as the Brazos River drainage along the coast from there to the escarpment of the Edwards Plateau; most populations elsewhere are either intermediate between the two species or show greater affinity with Q. fusiformis. On the Edwards Plateau, the live oak populations are small trees forming rhizomatous copses (shinneries) and having mostly acute acorns.

Populations of live oak on deep sands in south Texas differ from typical Quercus fusiformis in having broader, more rounded leaves, often with the secondary veins somewhat impressed abaxially, and relatively blunt, barrel-shaped acorns. These characteristics suggest introgresion from the Mexican-Central American species Q. oleoides Schlechtendal & Chamisso, which in its typical form reaches north only as far as southern Tamaulipas, Mexico. The name Q. oleoides var. quaterna C. H. Muller has been applied to what is apparently a shrub form of one of these Q. fusiformis × Q. oleoides hybrids.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Considerable variation in depth of lobing occurs in the leaves of Quercus alba (M. J. Baranski 1975; J. W. Hardin 1975); the species is easily distinguished from others, however, by the light gray-green, glabrous mature leaves and cuneate leaf bases.

In the past Quercus alba was considered to be the source of the finest and most durable oak lumber in America for furniture and shipbuilding. Now it has been replaced almost entirely in commerce by various species of eastern red oak (e.g., Q. rubra, Q. velutina, and Q. falcata) that are more common and have faster growth and greater yields. These red oaks also lack tyloses and therefore are more suited to pressure treating with preservatives, even though they are less decay-resistant without treatment.

Medicinally, Quercus alba was used by Native Americans to treat diarrhea, indigestion, chronic dysentery, mouth sores, chapped skin, asthma, milky urine, rheumatism, coughs, sore throat, consumption, bleeding piles, and muscle aches, as an antiseptic, and emetic, and a wash for chills and fevers, to bring up phlegm, as a witchcraft medicine, and as a psychological aid (D. E. Moerman 1986).

Numerous hybrids between Quercus alba and other species of white oak have been reported, and some have been named. J. W. Hardin (1975) reviewed the hybrids of Quercus alba. Nothospecies names based on putative hybrids involving Q. alba include: Q. ×beadlei Trelease (= Q. alba × prinus), Q. ×bebbiana Schneider (= Q. alba × macrocarpa), Q. ×bimundorum E. J. Palmer (= Q. alba × robur), Q. ×deami Trelease (= Q. alba × muhlenbergii), Q. ×faxoni Trelease (= Q. alba × prinoides), Q. ×jackiana Schneider (= Q. alba × bicolor), and Q. ×saulei Schneider (= Q. alba × montana).

(Discussion copyrighted by Flora of North America; reprinted with permission.)