| Fagaceae | Quercus marilandica var. ashei | Western Blackjack Oak | Xeric ridgetops, glades, dry prairies and cross-timber woodlands westward. | S. MO (?) and s. KS south to c. AR, e. TX, and sc. TX, especially on the Edwards Plateau (Hunt 1990). | 
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| Fagaceae | Quercus marilandica var. marilandica | Blackjack Oak | Upland forests and woodlands, usually on periodically droughty soils, as over shrink-swell clays, sandstones, deep sands, sands with clay lenses, and shallow soils over acidic bedrock. | NY (Long Island), NJ, se. PA, w. VA, s. OH, s. IN, c. IL, s. IA, and se. NE south to s. GA, Panhandle FL, and sc. TX (west to the Prairie border). There are historical accounts of the existence of prairies or barrens in the vicinity of Charlotte in the late eighteenth century, known as the "the blackjack lands". These areas were described as open and prairie-like, until the early nineteenth century, when they became dominated by dense forests of blackjack oak. The previously open condition was almost certainly maintained by fire, perhaps set by the Waxhaw Indians. Blackjack oak has long been considered an indicator of ‘poor’ soil (from an agricultural perspective), as in Guthrie (1820), who states in his discussion of NC, "the Black Jack land is generally poor, … and is avoided by farmers, as unproductive". | 
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