STANDLEY TREES AND SHRUBS OF MEXICO. 257 



Bracts and bractlets acute or acuminate, cuspidate. 



Staminodia minute ; sepals acute or acutish ; bracts sparsely villous. 



3. I. angustifolia. 

 Staminodia one-third as long as the filaments ; sepals obtuse or rounded 



at apex ; bracts densely villous 4. I. arenaria. 



Branches of the inflorescence densely canesceut or tomentose. 

 Leaf blades elliptic to oblanceolate-oblong, 12 to 20 cm. long, soon glabrate ; 



spikelets sessile; sepals sparsely lanate at base 5. I. tomentella. 



Leaf blades ovate to lanceolate, 8 cm. long or less, permanently pubescent ; 



spikelets mostly pedicellate ; sepals densely lanate 6. I. hartmanii. 



Flowers dioecious. 

 Branches of the inflorescence glabrous or nearly so. 



Leaves 25 to 33 cm. long 7. 1. herrerae. 



Leaves 2 to 15 cm. long. 

 Bracts subcoriaceous, rounded at apex ; lateral veins of the leaves nearly 



obsolete 8. I. palmeri. 



Bracts scarious, mucronulate ; lateral veins of the leaves coarse and promi- 

 nent 9. L interrupta. 



Branches of the inflorescence densely pubescent. 



Staminate spikelets glomerate at the ends of branches ; leaf blades about as 



broad as long, mostly suborbicular 10. I. rotundifolia. 



Staminate spikelets paniculate; leaf blades much longer than broad. 

 Sepals of the pistillate flowers rigid, green, the tips slightly spreading. 



11. I. pringlei. 

 Sepals of the pistillate flowers thin, whitish, the tips erect or incurved. 



Pubescence of branched hairs 12. I. stricta. 



Pubescence of simple hairs. 



Panicles on long naked peduncles, narrow, the branches usually short. 

 Leaves soon glabrate ; pubescence of the stems lustrous. 



13. I. nitens. 

 Leaves permanently pubescent, at least beneath ; pubescence dull. 



14. I. schafEneri. 

 Panicles short-pedunculate or usually sessile, broad, the branches 

 commonly elongate. 

 Leaves white beneath with a usually dense tomentum. 

 Spikes usually sessile, short; leaves thick, subrugose ; branches 



of the panicle stout 15. 1. cassiniaeformis. 



Spikes nearly all pedunculate, elongate ; leaves thin ; branches 



of the panicle slender, flexuous 16. 1. discolor. 



Leaves not white beneath, the pubescence of yellowish, straight 

 or loosely matted hairs. 

 Panicles very dense ; bracts and sepals villous only at base ; 

 sepals of the staminate flowers 2.5 to 3 mm. long. 



17. I. grandis. 

 Panicles loose and open ; bracts and sepals copiously villous ; 

 sepals of the staminate flowers 2 mm. long or sliorter. 



18. I. calea. 

 1. Iresine nigra Uline & Bray, Bot. Gaz. 21: 350. 1896. 



Veracruz and Chiapas. Central America ; type from San Pedro Sula, Hon- 

 duras. 



Shrub with slender branches; leaves mostly ovate, 4.5 to 14 cm. long, acute 

 to long-acuminate, glabrous. 



