1062 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



Anthers elongate, linear or subulate. 

 Anthers subulate, mostly 4 to 5 mm. long. 



Calyx limb closed in bud, breaking up into irregular lobes. 



Leaves long-acuminate 12. M. mexicana. 



Leaves acute or short-acuminate 13. M. lauriformis. 



('alyx limb open, truncate or regularly dentate. 

 Calyx oblong or oblong-cylindric. 



Filaments hirtellous ; leaves serrulate 14. M. leucocephala. 



Filaments glabrous; leaves entire 15. M. dodecandra. 



Calyx campanulate. 

 Calyx lobes subulate. 



Calyx tube 2.5 mm. long 16. M. anisotricha. 



Calyx tube 5 to 6 mm. long 19. M. saxicola. 



Calyx lobes rounded. 



Petals about 3 mm. long 17. M. guatemalensis. 



Petals 5 to 8 mm. long 18. M. erythrantha. 



Anthers linear, usually 3 mm. long or less. 



Anthers truncate at apex, the connective not appendaged anterioi-ly. 



20. M. minutiflora. 

 Anthers narrowed at apex or at least not truncate, the connective ap- 

 pendaged or tuberculate anteriorly. 



Flowers spicate 21. M. triplinervis. 



Flowers paniculate. 

 Branches of the panicle simple, spikelike. 



Leaves petiolate 22. M. bourgaeana. 



Leaves sessile or nearly so 23. M. impetiolaris. 



Branches of the panicle usually branched, not spikelike. 

 Leaves densely whitish-tomentulose beneath. 



Leaves mostly 7 to 15 cm. wide, usually denticulate. 



24. M. argentea. 

 Leaves mostly 3 to 7 cm. wide, entire or nearly so. 



Leaves shallowly cordate at base 25. M. albicans. 



Leaves rounded or obtuse at base 26. M. stenostachya. 



Leaves green beneath, never whitish-tomentulose. 

 Flowers secund upon the branches. 



Leaves quintuplinerved 27. M. scorpioides. 



Leaves 5-nerved 28. M. ambigua. 



Flowers not secund. 

 Leaves glabrous or glabrate beneath in age, when young often 

 minutely stellate-pubescent. 

 Leaves 3 or 5-nerved. 

 Leaves large, 7 to 40 cm. wide, subemarginate at base. 



29. M. calvescens. 

 Leaves smaller, 4 to 10 cm. wide, acute to rounded at base. 



Flowers mostly pedicellate 30. M. hyperprasina. 



Flowers all sessile or nearly so 31. M. laevigata. 



Leaves triplinerved or quintuplinerved. 

 Leaves sessile, or the petioles marginate almost to the base, 



the blades 7 to 10.5 cm. wide 32. M. langlassei. 



Leaves conspicuously petiolate, the petioles not winged, the 

 blades mostly 5 cm. wide or less. 



