I 



6 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN [VOL. 10 



Orectanthe ptaritepaiana is distinguished from 0. sceptrum largely by means 

 of vegetative differences, and to some extent on geographical grounds. The first 

 is characterized by well developed leafy stems and the prevalence of 3 or more 

 peduncles, as contrasted to 0. sceptrum which has very short stems and densely 

 rosulate leaves. Although variable in size and trivial detail, there seems to be 

 no way conclusively to separate the two species by floral distinction. They both 

 occupy the geographical range in eastern Guayana, but only 0. sceptrum is to 

 be found in western Venezuelan Guayana. Both species inhabit upper cumbre 

 habitats; only 0. sceptrum occurs also at low altitude (1000 m) on the Gran 

 Sabana. 



2. Abolboda Kunth in Humb. & Bonpl. PI. Aequin. 2: 25, 109. pi. 114. 1809. 

 Key to the Species of Abolboda 



1. Scapes provided with 1 or more pairs of subopposite bracts (exclusive of basally 

 subtending members. 



2. Scapes commonly with 2 (occasionally 3 or 4) pairs of bracts, or sometimes with 

 only one pair, then exceeding 3 dm in height ; herbs normally 3 dm or more high. 

 3. Spikes simple, not glomerate. 



4. Scapes simple, with a single terminal spike. 



5. Spikes globose or ovoid, the paired sepals and subtending bracts outwardly 

 arched or divergent at maturity, bracts % or less as long as the sepals. 



1. A. grandis. 



5. Spikes cylindric or elliptic-cylindric ; the paired and subtending bracts 



ascending or strict at maturity ; bracts more or less equaling, or at least 

 more than V 2 the length of the sepals. 2. A. macrostachya. 



4. Scapes branched, or if simple, with 1 or 2 axillary spikes below the terminal. 



6. Scapes paniculate ; spikelets 2-4-flowered, solitary and terminal on each 



branch ; leaves numerous, densely rosulate, gramineous, 5-10 mm long, 

 1.5-3.0 mm broad, narrowly acute, mucronate. 3. A. paniculate. 



6. Scapes simple; spikelets 1-flowered, terminal, and in addition axillary spike- 

 lets from the penultimate or antipenultimate vaginal bracts; leaves numer- 

 ous, densely rosulate, narrowly linear, triquetrous, obtuse, abruptly mu- 

 cronulate, 2-3 cm long, ca. 1 mm broad. 4. A. uni flora. 



3. Spikes glomerate; Rio Guainia drainage, Venezuela (and Colombia). 5. A. glomerata. 

 2. Scapes commonly with a single pair of bracts. 



7. Spikes cylindric or subcylindric, exceeding 2 cm in length ; leaves linear, obtuse, 

 20-30 cm long, considerably exceeding % the length of the scapes; upper Rio 

 Orinoco and Rio Guainia drainages. 6. A. Imeari folia. 



7. Spikes ovate or elliptic, 1.5 cm or less long. 



8. Leaves commonly y 2 or more the length of the scapes. 



9. tracts immediately subtending and much exceeding the spike ; spikes ovate, 

 1.0-1.5 cm long; sepals and subtending bracts ascending or strict; leaves 

 pseudo-equitant, gramineous, acute, 10-30 cm long, more or less equaling 

 the scapes. 7. A. spruce i. 



9. Bracts not immediately subtending the heads, affixed at more or less the 

 middle of the scape ; flowers and subtending bracts arcuate or subdivaricate. 

 10. Bracts of the scape narrowly lanceolate, attenuately acuminate, 2.0-2.5 

 cm long; cephalar bracts strongly productate; sepals 16-20 mm long; 

 plants 10-15 cm high; Yapacana Savannas, Amazonas, Venezuela. 8. A. bella. 

 10. Bracts of scapes lanceolate, abruptly acute, mucronulate, 1.0-1.2 cm 

 long; cephalar bracts ovate-lanceolate, ca. 7-8 mm long, short-produc- 

 tate ; sepals 9-10 mm long; plants 6-8 cm high; campos do Ariramba, 

 Rio Trombetas, Para, Brazil. 9. A. abbreviata. 



8. Leaves commonly *4 or less the length of the scape. 

 11. Leaves plane, or more than 1 mm broad. 



12. Leaves entire ; bracts of the scape 1.0-3.5 cm long. 



13. Flowers 5 or more per spike; bracts of the scape 2.5-3.5 cm long, the 



