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(Last Modified On 1/17/2013)
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(Last Modified On 1/17/2013)
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Genus
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QUERCUS L.
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PlaceOfPublication
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Gen. PI. ed. 5. 431. 1754.
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Synonym
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Erythrobalanus Schwarz, Notizbl. Bot. Gart. Mus. Berlin-Dahlem 13:8. 1936. Macrobalanus Schwarz, Notizbl. Bot. Gart. Mus. Berlin-Dahlem 13:8. 1936.
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Description
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Trees or shrubs; leaves alternate, simple, petiolate, blades entire, toothed, or lobed, persistent or deciduous, stipules associated with the buds, ligulate, often caducous; flowers monoecious; staminate flowers in flaccid pendulous aments, the perianth about 5-lobed, stamens 5 to 10, free; pistillate flowers solitary or clustered, subsessile or peduncled, enclosed in an involucre of numerous flat scales, the peri- anth 6-lobed, ovary 3-carpellate, 1-celled, ovules 6 (5 abortive), styles 3, short; fruit a nut (acorn), 1-seeded, partly enveloped by an involucre (cup) of flat or basally thickened scales, maturing in 1 or 2 seasons.
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Habit
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Trees shrubs
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Note
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The oaks comprise a more or less temperate zone group and are therefore, with few exceptions, confined in Panama to the high mountains near the Costa Rican boundary, apparently no species occurring below an elevation of 1200 m. In addition to the ten species definitely known to exist in Panama, it is very likely that several of the closely adjacent Costa Rican species may also occur across the boundary in the higher mountains of upper Panama. Future more detailed collec- tions in this area will possibly reveal these as well as a few additional undiscovered endemics.
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Key
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a. Bark rather soft gray and scaly, leaves if toothed only mucronately tipped or rounded, never spinose- or aristate-tipped, stigmas abruptly dilated on short styles, fruit annual, cup scales usually prominently thickened basally and loosely appressed apically, acorns with the shell glabrous on the inner surface, abortive ovules basal. subgenus LEPIDOBALANUS. White oaks. b. Twigs of the season persistently and densely fulvous-tomentose. c. Leaves obovate to elliptic-oblanceolate, not tapering, the base rather broad, cuneate to cordate, subentire or low-toothed, petioles over 6 (usually over 10) mm. long. d. Leaves deeply broad-cordate ........................... 1. Q. SEIBERTII dd. Leaves cuneate to truncate at base ................ 2. Q. DAVIDSONIAE cc. Leaves oblanceolate, tapering to a cuneate or narrowly rounded base, coarsely toothed above the middle, petioles 3 to 5 mm. long. 3. Q. OOCARPA bb. Twigs of the season glabrate or sparingly pubescent or gray-tomentose. e. Leaves completely glabrate. f. Leaves long-acuminate, entire, fruit very small, cup scales tomentose at base only, the apices glabrous, thin, and loosely appressed.................................................... 5. Q. PANAMANDINAEA ff. Leaves not acuminate, or if so then coarsely toothed, fruit very large, cup scales pubescent all over ................. 4. Q. CORRUGATA ee. Leaves villous or tomentose beneath or at least the midrib strigose or stellate-tomentose. f. Leaves rarely over 6 (8) cm. long, acorns scarcely more than 1 cm. in diameter............................. 6. Q. COPEYENSIS ff. Leaves rarely less than 10 cm. long, acorns 2.5 cm. broad or broader. g. Leaves obovate to elliptic-oblanceolate, not markedly taper- ing, the base rather broad, cuneate to cordate, obscurely low- toothed, petioles 6 to usually 10 or 12 mm. long ............ 2. Q. DAVIDSONIAE gg. Leaves oblanceolate, tapering to the cuneate or narrowly rounded base, coarsely toothed above the middle, petioles 3 to 5 mm. long ................... 3. Q. OOCARPA aa. Bark rather hard, black and furrowed but scarcely scaly, leaves if toothed aristate-tipped, never round-lobed or mucronate, stigmas gradu- ally (or rather abruptly) dilated, on long styles, fruit biennial or annual, cup scales scarcely thickened basally (in Panama) and usually tightly appressed apically, acorns with the shell tomentose on the inner surface, abortive ovules apical or basal ....... subgenus ERYTHROBALANUS. Black oaks h. Cup scales very loosely appressed ............ 7. Q. HUMBOLDT!! hh. Cup scales rather closely appressed. i. Leaves small, averaging under 8 cm. long, glabrate except for discrete tufts in the axils of the principal veins beneath ................. 8. Q. SEEMANNII ii. Leaves large, averaging over 12 cm. long, distinctly pubescent about the midrib beneath j. Petioles very short, 2-6 mm. long, blades very thin ................ 9. Q. GULIELMI-TRELEASEI jj. Petioles elongate, 12-23 mm. long, blades thick and coriaceous... 10. Q. BARUENSIS
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