1958] 



THE BOTANY OF THE GUAYANA HIGHLAND PART III 



37 



8. Schoenocephalium Seub. Fl. Bras. 3 1 : 130. 1847; emend. Maguire. 



The genus Schoenocephalium as presented by Seubert in the Flora brasilien- 

 sis was based on two collections obtained by Martius in savannas near "montis 

 Arara-Coara" ( Araracuara) , Rio Caqueta, Amazonas, Colombia. These became 

 the types, respectively, of the two species proposed by Seubert, viz., S. mariianum 

 and S. arthrophyllum. The latter, however, belongs to the very distinct and 

 unrelated genus Monotrema established by Kornicke 12 years later. 



Both of these collections have been in my hands for the purpose of this study. 



It is clear that the generic description of Schoenocephalium as drawn up by 

 Seubert (so noted by Kornicke I.e.) was largely based on the structural charac- 

 ters of the types of S. martianum, the specimens of which are in early anthesis. 



Apparently only the characterization "Semina subglobosa, interdum 



appendiculata." applies to the types of Seubert 's S. arthrophyUum in which 

 mature seed are present. 



The generic description of Schoenocephalium must thus be emended to rectify 

 the errors of the original diagnosis, and S. arthrophyUum must, in the proper 

 place, be transferred to Monotrema. 



Heads globose, bibracteate ; spikelets radiate ; braeteoles gradate ; sepals free 

 to the base ; petals lanceolate, included within the sepals which do not open dur- 

 ing anthesis, claws connate ; stamens 6, the filaments adnate to the corolla-tube ; 

 anthers 4-celled, the apex cruciform. 4-porous, sometimes the lateral pores becom- 

 ing confluent; ovary trilocular. each locule biovulate (4-ovulate in 8. schultesii) ; 

 styles terete, truncate, terminally minutely circumciliate ; seed subprismatic- 

 subpyramidal. longitudinally striate. 



Herbaceous perennials with a short subcarnose caudex ; sheaths more or less 

 equitant, conduplicate, on the ventral side extending into the zone of union with 

 the blade as. an acutely attenuate area, and conversely the blade extending along 

 the "back" of the sheath, ventrally for ea. half the length of the sheath; the 

 blades narrowly linear. A genus of five known species confined to low altitudes 

 in the Upper Orinoco and Xegro drainages. 



Type : Schoenocephalium martianum Seub. 



Key to the Species of Schoenocephalium 



1. Sepals clearly exceeding the upply braeteoles by (3) 4-5 mm in length. 

 2. Leaf -blades linear, plane; bladeless sheaths lacking. 



3. Leaf -blades 8 mm or less broad; sheaths submembranous ; interior braeteoles 

 6-7 mm long, nerveless; anthers 2.75-3.0 mm long; plants of the Bio Caqueta, 

 Amazonas, Colombia. 1. S. martianum. 



3. Leaf -blades 14-16 mm broad; sheaths subcoriaceous ; interior bractlets 9-10 mm 

 long, obviously 7-nerved; anthers 4.5-5.0 mm long; plants of the Rio Atabapo, 

 Amazonas, Venezuela. 2. S. coriaceum. 



2. Leaf -blades terete ; bladeless sheaths present ; plants of the Rio Guainia and Rio 



Pacimoni, Amazonas, Venezuela. 3. S. teretifolium. 



1. Sepals exceeding the upper braeteoles 2 (3) mm or less in length. 



4. L'pper braeteoles cucullate, essentially equaling the sepals; leaves 3-5 dm long, 

 2.0-3.5 cm broad, the midrib inconspicuous; anthers ca. 3 mm long; ovules 2 per 

 loeule; plants of the L'pper Rio Orinoco* and Rio Siapa, Amazonas, Venezuela. 



4. S. cucullatum. 



■4. Lpper braeteoles not eueullate, 1-2 (3) mm shorter than the sepals; leaves 7-9 

 dm long, 1.5-2.0 cm broad, the midrib prominent; anthers ca. 5 mm long; ovules 

 4 per locule; plants of the Rio Apaporis, Vaupes, Colombia. 5. S. schultesii. 



12 Lihnaea 37: 475. 1873. 



