146 contribut:ions from the national herbarium. 



Spikes solitary, opposite the leaves. 



Flowers pedicellate Subgenus 2. Ottonia. 



Flowers sessile. 

 Stamens 2 or 3. 



Stamens 2 Subgenus 3. Coccobryon. 



Stamens 3 Subgenus 4. Carpunya. 



Stamens 4 to 6. 



Stamens 4 Subgenus 5. Steffensia. 



Stamens 5 or 6 Subgenus 6. Enckea, 



Subgenus 1. HECKERIA. 



Leaves peltate 1. P. cuernavacanum. 



Leaves not peltate. 



Petioles as long as the blades or longer 2. P. cordillerianum. 



Petioles scarcely more than half as long as the blades 3. P. umbellatum. 



Subgenus 2. OTTONIA. 



Leaves pubescent beneath on the nerves 4. P. muelleri. 



Leaves glabrous. 



Leaves 7-nerved, about 6.5 cm. wide 5. P. yucatanense. 



Leaves 5-nerved, 2.5 to 4 cm. wide. 



Stamens 4 6. P. neesianum. 



Stamens 5 or 6 7. P. disjunctum. 



Subgenus 3. COCCOBRYON. 



Leaves acuminate, the lower ones cordate at the base, 7 or 9-nerved. 



8. P. diandrum. 

 Leaves long-acuminate, the lower ones rounded at the base, 5 or 7-nerve<l. 



9. P. papantlense. 



Subgenus 4. CARPUNYA. 



Anthers articulate 10. P. karwinskianum. 



Anthers not articulate. 



Leaves subcoriaceous 11. P. caladiifolium. 



Leaves membranaceous. 



Leaves puberulent beneath along the nerves 12. P. sanctum. 



Leaves glabrous. 



Peduncles as long as the petioles 13. P. commutatum. 



Peduncles much shorter than the petioles 14. P. zacuapanum. 



Subgenus 5. STEFFENSIA. 



Stigmas 2 15. P. bourg'eaui. 



Stigma 3. 



Style present 16. P. teapense. 



Style none. 

 Fruit trigonous or obovoid. 

 Bracts cucullate with inflexed apex or obovate. 



Lea\»es pinnate-nerved 17. P. lapathifolium. 



Leaves palmate-nerved 18. P. schlechtendalii. 



