UNDERGROUND SYSTEMS OF GAMBEL OAK (QUERCUS GAMBELII) IN CENTRAL UTAH

Excavation to a depth of 1 m of a 3 x 4 m portion of a clone of Quercus gambelii revealed the presence of a massive underground system of lignotubers, interconnecting rhizomes and roots. Lignotubers comprised the greatest proportion (72%) of the total below ground biomass (81 t/ha). Lignotubers are distinctive in appearance: they are an enlarged stemlike structure with numerous clusters of adventitious buds on the surface. Anatomically, they are comparable to the above ground stems with growth rings. Lignotubers are lobed and distorted, giving the appearance of a burl. Rhizomes are round to I-beam in shape with a star-shaped pith, distinct annual rings, bud traces, and branch gaps. There were also clusters of adventitious buds on rhizomes, although not as dense as those on the lignotubers. Roots are oval in cross section with discernible growth rings, no pith, and no bud traces. The lignotuber is the most important regenerative underground structure, but the rhizome appears to be the primary means of clone expansion.