Quercus myrtifolia, or myrtle oak, is a species of red oak found in the south-central peninsula of Florida (Abrahamson & Layne 2003: 2477). Q. myrtifolia is associated with sandhill and flatwood communities (Abrahamson & Layne 2003: 2479).
In a study near Florida’s Lake Wales Ridge, the acorn crop of Q. myrtifolia was the highest of five different oak species, with a mean number of 13.4 ± 2.3 acorns per ramet or stem (Abrahamson & Layne 2003: 2481). In sandhill and flatwood communities Q. myrtifolia produced an acorn count five times higher than was produced in the scrub community with 19.6 ± 3.5 acorns and 18.0 ± 4.02 acorns respectively. Acorns produced in the shrub only reached numbers of 3.5 ± 0.65 per ramet (Abrahamson & Layne, 2003: 2481).
Q. myrtifolia have 3.6 and 3.7 year acorn production cycles in flatwoods and sandhill communities, respectively (Abrahamson & Layne 2003: 2484). In a shrub environment they have a much longer cycle that lasts 5.5 years (Abrahamson & Layne, 2003: 2484). Acorn production was positively correlated to the rainfall during the previous month of October in scrub habitats (Abrahamson & Layne, 2003: 2486). Acorn production in sandhill communities was positively correlated to rainfall in the months of June through August for three years prior (Abrahamson & Layne 2003: 2486). Low winter temperatures do not affect the acorn crop (Abrahamson & Layne 2003: 2488).
Abrahamson, W.G., & Layne, J.N. 2003. Long-term patterns of acorn production for five oak species in xeric Florida uplands. Ecology 84: 2476-2492.
Abrams, M.D. 1990. Adaptations and responses to drought in Quercus species of North America. Tree Physiology 7:227-238.
Trees or shrubs , evergreen, to 12 m. Bark gray and smooth distally, dark and shallowly furrowed near base. Twigs dark red-brown, 1-2.5(-3) mm diam., persistently pubescent, rarely almost glabrous. Terminal buds reddish to purplish brown, ovoid, 2-5.5 mm, glabrous or with tuft of tawny hairs at apex. Leaves: petiole 1-5 mm, glabrous, occasionally sparsely pubescent. Leaf blade elliptic to narrowly or broadly obovate, occasionally spatulate, 15-50(-70) × 10-25(-35) mm, base cuneate to rounded, margins entire, somewhat revolute, with 1-4 awns, apex obtuse or rounded; surfaces abaxially glabrous except for axillary tufts of tomentum, occasionally yellow-scurfy, adaxial surface planar, glabrous. Acorns biennial; cup saucer-shaped to shallowly goblet-shaped, 4-7 mm high × 8.5-14.5 mm wide, covering 1/4-1/3 nut, outer surface puberulent, inner surface half to fully pubescent, scale tips tightly appressed, acute; nut broadly ovoid to globose, 9.5-14 × 8-13 mm, glabrate, scar diam. 5-8 mm.
This species flowers one to two weeks earlier than Q . inopina (A. F. Johnson and W. G. Abrahamson 1982).
Quercus myrtifolia reportedly hybridizes with Q . incana (= Q . × oviedoensis Sargent), but E. J. Palmer (1948) questioned the identification of the type specimen; the brief description by Sargent suggests that the specimen may be from an individual of Q . inopina . D. M. Hunt (1989) cited evidence of hybridization with Q . arkansana , Q . hemisphaerica , Q . inopina , Q . laurifolia , Q . marilandica , Q . nigra , and Q . pumila (Hunt suggested that the last may give rise to occasional reports of annual fruiting in Q . myrtifolia ).