1958] 



THE BOTAXY OF THE GUAYAXA HIGHLAND PART III 



45 



frequent, Cano Hechimoni, 8 kin above mouth, Rio Siapa, at 120 m alt., Feb 9, 1954, Maguire, 

 Wurdack # Bunting 37662. 



Duckea flava has no more in common with Monotrema than D. squarrosa and 

 D. cyperaceoidea have with the tightly knit genus Cephalostemon. As assembled 

 here, the genus is possibly less homogeneous than is characteristic of genera in 

 the Rapateaeeae, yet the four species are held together quite satisfactorily by 

 similarity of anthers and seed. 



12. Spathanthus Desvaux, Ann. Sci. Xat. 13: 45. 1828. 



Involucral bract solitary, spathaeeous, lanceolate ; inflorescence spieate, adnate 

 to the spathe ; spikelets sessile, numerous ; bractlets numerous, distichous ; petals 

 lanceolate ; anthers 4-locular, dehiscing by a single apical inequilaterally toothed 

 pore; ovary 3-celled, subapocarpellate, two carpels abortive, the third maturing, 

 bearing a single ovule ; style centrally subbasal; capsule unilocular, bivalvate. 

 monospermous ; seed oblong-elliptic, striate, subbasally affixed. 



Uliginose terrestrial herbs with distichous leaf-sheaths and linear blades; 

 peduncles 1-several, solitary in the leaf axil. 



Type: Spathanthus unilateralis (Rudge) Desv. 



Key to the Species of Spathanthus 



1. Leaf-blades commonly 4-7 cm broad; bracteoles acute or acuminate, short-pungent; 



plants of Guiana, from Venezuela to Brazil. 1. S. unilateralis. 



1. Leaf -blades commonly 1-3 cm broad; bracteoles obtuse, more or less apiculate ; 



plants of the Rio Negro, Upper Eio Orinoco drainage. 2. S. bicolor. 



1. Spathanthus unilateralis (Rudge) Drsv. Ann. Sci. Xat. 13: 45. pi. i, /. 1. 1828. 



Key to the Varieties of Spathanthus unilateralis 



1. Leaf -blades gradually narrowed to an acute, usually attenuate base; petioles 5-20 cm 



long or essentially lacking. var. unilateralis. 



1. Leaf -blades abruptly contracted at the base; petioles manifest, 15-40 cm long. 



2. Leaf-blades cordate or subcordate at the base. var. jenmani. 



2. Leaf-blades inequilaterally obtusely contracted at the base. var. abruptus. 



Spathanthus unilateralis var. unilateralis. 



Mnasium iinilaterale Rudge, PI. Guian. 1: 12. pi. 11. 1805. 



Bapatea unilateralis (Rudge) Schult. & Schult. in Roem. & Schult. Syst. Yeg. 7: 1149. 1830. 



Type: Guiana [French Guiana], Herb. Rudge, British Museum. The plate, 

 pi. 4, is a clearly drawn representation of the species. 



Distribution : Terrestrial perennial herbs of low altitude, swampy rainforest ; 

 widely distributed, Venezuela to Para and Amazonas, Brazil. 



Fig. 7. A-F, Duclcea junciformis. A, habit, X %; B, inflorescence, X 1%; C, diagram- 

 matic representation of corolla, X 8; D, stamen, X 10, tip of anther, X 10; E, capsule, X 7; 

 F, ventral view of seed, X 10; drawn from Maguire Sr Wurdack 35697. G-L, Monotrema 

 braeteatum. G, habit, X Vi\ H, inflorescence, X 1-/4; I, diagrammatic representation of 

 flower, X 7%; J, stamen, X 10; K, capsule, X 10; L, seed, X 10; drawn from Maguire, 

 Cowan 4- Wurdack 30461 and Maguire, Wurdack $ Bunting 36569, 36605. M, Monotrema 

 affine, inflorescence, X l 1 /^, drawn from Maguire, Wurdack 4' Bunting 36570. 



