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THE BOTANY OF THE GUAYANA HIGHLAND— PART II 



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ascending, branching from near the base, the branchlets spreading, few-flowered; 

 spikelets 1.3-1.4 mm long, elliptic or obovate, acute, sparsely pilose; first glume 

 1/2-2/3 as long as the spikelet, narrow, 1-nerved, acute; second glume and 

 sterile lemma equal, pointed beyond the fruit, the lemma without a palea or 

 staminate flower; fruit 1 mm long, broadly elliptic, subobtuse, white, striate. 



TYPE: on waterfall, in spray, Culebra Creek, alt. 1500-1600 m, Cerro Duida, 

 Rio Cunucunuma, Amazonas, Venezuela, November 21, 1950, Bassett Maguire, 

 P. S. Cowan & John J. Wurdack 29636; U. S. National Herbarium No. 2,040,215. 



Resembling Panicum rivale Swallen, but differing in having shorter-pediceled, 

 pilose spikelets, truncate rather than arcuate ligule, and acuminate blades. 



The following seven species, with P. wurdackii and P. steyermarkii,* are 

 related to Panicum loreum Trin. Other species of this group previously de- 

 scribed from the Guayana Highland are P„ eligulatum N. E. Brown, P. tropidoble- 

 phore Tutin, P. curvifolium Swallen, and P. tatei Swallen. All are similar in 

 habit, but differ markedly in specific characters. With the exception of P. 

 sipapoense which has a short ligule, there is no differentiation between sheath 

 and blade. 



Panicum vannum Swallen, sp. nov. 



Perenne; culmi ca. 90 cm alti; foliae confertae distichae; vaginae elongatae, 

 compressae, ecarinatae basi dense pilosae laminis deciduis; laminae 30-40^ cm 

 longae, 10-13 mm latae, acuminatae apice naviculares, marginibus scabrae, 

 interdum sparse pilosae; panicula 14 cm longa, 5 cm lata, ramis anguste adscend- 

 entibus; spiculae 2.8-3 mm longae; gluma prima acuta spicula 1/2 brevior carina 

 scabra; gluma secunda et lemma sterile aequalia fructu longiora; fructus 2.4 mm 

 longus, ellipticus, laevis, flavidus. 



Perennial; culms about 90 cm high? (base wanting); basal leaves crowded, 

 conspicuously distichous, forming a fan-shaped cluster; sheaths elongate, 

 flattened but not keeled, rather densely pilose at the base; ligule wanting, the 

 demarcation between sheath and blade not evident, although the blades are 

 apparently deciduous; blades mostly 30-40 cm long, 10-13 mm wide, narrowed 

 toward the base, acuminate with a firm navicular tip, the margins very scabrous, 

 otherwise glabrous or with a few scattered long hairs; panicle 14 cm long, about 

 5 cm wide, the branches narrowly and stiffly ascending; spikelets 2.8-3 mm long; 

 first glume acute, about half as long as the spikelet, the midnerve scabrous; 

 second glume and sterile lemma equal, pointed beyond the fruit; fruit 2.4 mm 

 long, elliptic, smooth, straw-colored. 



TYPE: in old fruit; locally frequent in colonies on south slope of Cumbre 

 Camp Carlo toward Carlo Grande, alt. 1500-1700 m, Cerro de la Neblina, Rio 

 Yatua, Amazonas, Venezuela, January 16, 1954, Bassett Maguire, John J. 

 Wurdack & George S. Bunting 37327; U. S. National Herbarium No. 2,182,161. 



Panicum sipapoense Swallen, sp. nov. 



Perenne; culmi erecti ca. 60 cm alti; vaginae confertae ad basin dense vil- 

 losae, planae; ligula 0.2-0.4 mm longa plerumque dense ciliata; laminae lineares, 

 elongatae, usque ad 4 mm latae, ad basin attenuatae, basi longipilosae; panicula 

 longe exserta, pyramidata, 12 cm longa, 14 cm lata ramis et ramulis patentibus; 

 spiculae 2.7-2.8 mm longae, glabrae; gluma prima subobtusa spicula 1/2 brevior 

 vel paulo longior vel brevior; gluma secunda et lemma sterile subobtusa fructum 

 aequantia; lemma palea carinis ciliata; fructus 2.2-2 4 mm longus, laevis, flavi- 

 dus. 



*Described in "Botany of the Chimanta Massif" (Mem. N. Y Bot„ Gard. 9:393-439. 

 1956.) 



