THE CENTRAL AMERICAN SPECIES OF QUERCUS 13 



SYSTEMATIC TREATMENT 

 QUERCUS L., Gen. PL ed. 5. 431. 1754. 



Cerris Raf., Alsog. Amer. 29. 1838. 



Scolodrys Raf., Alsog. Amer. 29. 1838. 



Macrobalanus Schwarz, Notizbl. Bot. Gart. Mus. Berlin-Dahlem 



13: 8. 1936. 

 Erythrobalanus Schwarz, Notizbl. Bot. Gart. Mus. Berlin-Dahlem 



13: 8. 1936. 



Shrubs to large trees. Pith star-shaped, continuous; wood usually 

 hard with both uniseriate and multiseriate rays, vessels grouped in 

 a matrix of wood-parenchyma, either diffuse-porous or ring-porous, 

 often plugged by tyloses. Buds crowded toward the ends of the usu- 

 ally fluted twigs. Leaves alternate, usually distinctly petioled, never 

 quite sessile, simple, entire or toothed or pinnately lobed, pinnately 

 veined; the stipules associated with the buds rather than the leaves, 

 subulate to ligulate, promptly caducous or sometimes persistent. 

 Monoecious; staminate flowers in elongate flaccid catkins, apetalous, 

 the calyx of 5 lobes fused into a more or less bowl-shaped perianth 

 enclosing 5 to 10 free stamens with short anthers and slender filaments; 

 pistillate flowers in a reduced catkin with a stiff woody rachis either 

 short or long and 1- to several-flowered, calyx of 6 sepals adherent to 

 the bases of the styles and fused into a tube, pistil of 3 carpels com- 

 prising a single 3-celled ovary (each cell containing 2 ovules) and 3 

 free styles which are ventrally stigmatic toward the dilated apex. 

 Fruit 1-celled and 1-seeded, the 5 remaining ovules aborted and ad- 

 hering to the developed seed, the seed enclosed in a shell (forming a 

 nut or acorn) and seated in a cup or involucre formed (in our species) 

 of scales (each with a more or less aborted bud in its axil), growing 

 from a compressed inflorescence, the cup enveloping the whole nut 

 or covering it only at the base. 



Type species: Quercus robur L. 



Key to Species 



1. Bark rather soft gray and scaly, leaves if toothed only mucronate- tipped or 

 rounded, never spinose- or aristate-tipped, stigmas abruptly dilated on 

 short styles, fruit annual, cup scales usually prominently thickened bas- 

 ally and loosely appressed apically, acorns with the shell glabrous on 

 the inner surface, abortive ovules basal. (See also p. 15). 



I. LEPIDOBALANUS. White Oaks. 

 2. Twigs of the season persistently and densely fulvous-tomentose. 



3. Leaves oblanceolate, tapering to the cuneate or narrowly rounded base, 

 coarsely toothed above the middle, petioles 3 to 5 mm. long. 



4. Q. OOCARPA. 

 3. 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. 



4. Leaves deeply broad-cordate 2. Q. seibertii. 



4. Leaves cuneate to truncate at base. 



5. Leaves short-acuminate or merely acute, veins 18 to 20 on each 



side, petioles 12 to 25 mm. long 1. Q. insignis. 



5. Leaves long-acuminate, veins about 13 to 18 on each side, petioles 



6 to 12 mm. long 3. Q. davidsoniae. 



2. Twigs of the season glabrate or sparingly pubescent or gray-tomentose. 

 6. Leaves with persistent unbroken short tomentum beneath or the lower 

 surface canescent with minute appressed stellate hairs. 

 323472°— 42 2 



