THE CENTRAL AMERICAN SPECIES OF QUERCUS 15 



22. Leaves thick and leathery, glabrate except for the veins, 



the margins markedly revolute, entire or finely 



toothed. 



23. Leaves more than twice as long as broad, veins and 



reticulum very prominent beneath (plants of 



Guatemala) 11. Q. pacayana. 



23. Leaves less than twice as long as broad, veins some- 



what raised but reticulum very obscure beneath 

 (plants of Costa Rica and Panama) . 



12. Q. COPEYENSIS. 

 22. Leaves rather thin or if somewhat leathery then per- 

 sistently stellate-pubescent beneath and coarsely 

 few-toothed or undulate toward the apex. 



24. Leaves thin, glabrate except for the strigose midrib 



and veins or rarely fulvous-stellate-tomentose 

 along the midrib beneath, subentire, twigs strik- 

 ingly whitened or if brownish then persistently 

 villous, the lenticels not evident.. _ 9. Q. aaata. 

 24. Leaves somewhat thickened and leathery, stellate- 

 pubescent beneath, coarsely few-toothed toward 

 the apex, twigs brown with pale lenticels and 



glabrate 16. Q. vicentensis. 



Bark rather hard, black, and furrowed but scarcely scaly, leaves if toothed 

 aristate-tipped, never round-lobed, stigmas gradually (or rarely abruptly) 

 dilated, on long styles, fruit biennial or annual, cup scales scarcely 

 thickened basally (or if so the leaf characters definitely as here de- 

 scribed) and usually tightly appressed apically, acorns with the shell 

 tomentose on the inner surface, abortive ovules usually apical. 



II. ERYTHROBALANUS. Black Oaks. 

 25. Leaves entire or the margins crisped but in no way toothed or aristate. 

 26. Apex broadly rounded, or if narrowly rounded not aristate. 



27. Blades granular-bullate beneath, from tomentose becoming more or 

 less glabrate. 

 28. Cup scales very loosely appressed, cups 25 mm. broad. 



22. Q. COSTARICENSIS. 



28. Cup scales closely appressed, cups at most 15 mm. broad. 



33. Q. TRISTIS. 



27. Blades smooth beneath, that is not bullate, glabrous or at most tufted 

 in the axils of the veins, fruit small and the cup scales very closely 

 appressed. 



29. Blades very shiny on both surfaces but especially above, very thick 



and hard, the mature cups usually 15 mm. broad, saucer- 

 shaped 25. Q. DURATIFOLIA. 



29. Blades dully lustrous on both surfaces or the under surface waxy- 

 glaucous, leathery but scarcely hard, the mature cups seldom over 



10 mm. broad, cup-shaped 26. Q. sapotaefolia. 



26. Apex acute and aristate-tipped or acuminate. 

 30. Blades low-bullate or granular-bullate beneath. 



31. Leaves variously pubescent or glabrate but not persistently loose- 

 tomentose beneath. 

 32. Petioles over 5 mm. long, or if shorter then the leaves toothed 



and aristate 33. Q. tristis. 



32. Petioles 2 to 3 mm. long, leaves never toothed. 



33. Leaves not over twice as long as broad, acute but not long- 

 acuminate, very thick and leathery. _ 22. Q. costaricensis. 

 33. Leaves over twice as long as broad, long-acuminate or rarely 



only acute, rather thin but firm 23. Q. irazuensis. 



31. Leaves persistently loose-tomentose beneath. 



34. Twigs persistently velvety-tomentose, waxy-glaucous as well as 



bullate where denuded 34. Q. brachystachys. 



34. Twigs glabrate or scurfy but not velvety, leaves not waxy-glaucous 

 beneath. 

 35. Leaves rather sparsely short-tomentose or merely crisped- 

 villous beneath, at most low-bullate __ 45. Q. crispipilis. 

 35. Leaves rather densely thick-tomentose or eventually somewhat 

 glabrate but never sparsely or short-tomentose, granular- 

 bullate ._45a. Q. crispipilis var. pannosifolia. 



