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PACIFIC SCIENCE, Vol. XVII, October 1963 
long, 2-4 mm apart, both the upper and lower 
surfaces rugose-reticulate from the heavy cross 
veinlets, the blade M-shaped in section and the 
pleats running almost to the tip; peduncle 70 
cm long; spike with 5-7 syncarps, the largest 
14-18 cm long, 11-12 cm in diameter, ovoid 
but distinctly 3 -sided; drupes numerous, these 
3. 5-4.3 cm long, 8-10 mm wide and thick, nar- 
rowly ellipsoid, the sides smooth, plane or gently 
curved, 5 -angled, upper 1/7 free; pileus oblate- 
semiorbicular, firm, shedding singly, ending in 
a style 6-8 mm long, bony, horn-like, entire 
( rarely bifid ) , strongly curved towards the apex 
of the syncarp, pale brownish; stigma 3-4 mm 
long, lanceolate, brown papillose; endocarp 
slightly submedian, 25 mm long, the lateral 
walls 0.1 mm thick, cartilaginous, stramineous, 
the inner surface shining, the apex produced 
upwards into a long lanceoloid tip; seeds 15-16 
mm long, 5-6 mm in diameter, ellipsoid; apical 
mesocarp fibrous around the margin, cavernous 
within; basal mesocarp fibrous and fleshy. 
holotypus: Thailand (Siam), Kaw Tao, 
Surat, in high evergreen forest, under 5 m. alt., 
April 16, 1927, A. F . G. Kerr 12,772 (bk). 
specimens EXAMINED: Thailand (Siam), 
Kaw Tao, Surat, evergreen forest, 300 m. alt., 
Sept. 21, 1928, A. F. G. Kerr 16,052 (bk); 
Wangka, Kanburi, by stream in evergreen forest, 
700 m. alt., Feb. 3, 1926, A. F . G. Kerr 10,432 
( BK ) ; Ta Ngaw, Chumpawn, common along 
streams in savannah evergreen {forest}, Jan. 22, 
1927, A. F. G. Kerr 11,601 (bk). 
DISCUSSION : Pandanus unicornutus is a mem- 
ber of the section Rykia, as is its closest relative, 
P. penangensis Ridley, a Malayan species which 
has the drupes 42-47 mm long, 6-1 mm thick; 
endocarp 32-33 mm long, the lateral walls 1-1.5 
mm thick; and the leaves 12 cm wide, near the 
base the margins with prickles 1.3-1. 5 mm long, 
4-7 mm apart. P. unicornutus has the drupes 
35-43 mm long, 8-10 mm thick; endocarp 25 
mm long, the lateral walls 0.1 mm thick; and 
the leaves 10-11 cm wide, near the base the 
margins with spines 4.5-6 mm long, 7-15 mm 
apart. 
The epithet is from the Latin unus, one, cor- 
nutus, with a horn, in allusion to the usual single 
hornlike style. 
