Revision of the Genus Pandanus Stickman, Part 15 
Malayan Species Described by H. N. Ridley 
Harold St. John 1 
As IN MANY OTHER GENERA Henry N. Ridley, 
director of the Botanic Garden, Singapore, made 
noteworthy contributions to the knowledge of 
the Malayan species of Pandanus. His species 
were validly published in local journals or in 
his books. He described them briefly, usually 
giving some details of the stem, leaves, appear- 
ance of the syncarp, length of style, and width 
of the exposed tip of the drupes. He cited 
specimens but did not adopt the type method. 
None of his species were illustrated. The writer 
has investigated Ridley’s species, sought the 
holotypes or has chosen lectotypes in the Singa- 
pore herbarium. These specimens were kindly 
made available by the present director, Dr. H. 
M. Burkill. 
Ridley’s species of Pandanus are nearly all 
good, and these are to be maintained. He placed 
most of his species in either the section Rykia 
or in Aero stigma. As will be noted in the treat- 
ment that follows, additional sections are to be 
found among his species. The large majority 
of Ridley’s species are treated in this article; 
and the few remaining ones will be illustrated 
and described in subsequent parts when their 
type specimens have been located and studied. 
SECTION Aero stigma 
Pandanus aurantiacus RidL, Roy. Asiat. Soc., 
Straits Branch, Jour. 41: 49 (1904) = 
1903; FI. Malay Penin. 5: 81, 1925; 
Martelli, Webbia 4(2): t. 30, figs. 10- 
13, 1914; (sect. Aero stigma) 
Fig. 172 
DIAGNOSIS OF LECTOTYPE: "Large branching 
shrub with stems 3.6 m. tall, 5-7.5 cm. through”; 
leaves "glaucous green”; the lower bracteal leaf 
1.26 m long, 4.2 cm wide, coriaceous, 1 -ribbed 
1 B. P. Bishop Museum, Honolulu 17, Hawaii, 
U. S. A. Manuscript received July 19, 1961. 
but 2 -pleated and in section M-shaped, the 
blade sword-shaped, from the base gradually 
tapering to the approximately 20 cm long subu- 
late apex which about 10 cm down is 1.5 mm 
wide, at midsection each side with 42 parallel 
secondary nerves, the base amplexicaul and un- 
armed but beginning 7-8 cm up the margins 
with serrations 0.6-0.9 mm long, 1-2.5 mm 
apart, pale; the midrib below from 21 cm up 
with serrations 0. 3-0.5 mm long, 2-10 mm 
apart, subulate-tipped; at midsection the mar- 
gins and midrib below with serrae 1-1.5 mm 
long, 1-3 mm apart; near the apex the margins 
and midrib below with rigid serrulations 0.4-0.6 
mm long, 2-4 mm apart; pistillate inflorescence 
43 cm long, 12-13 mm in diameter, trigonous, 
bracted, spicate, bearing in the terminal 20 cm 
5 syncarps which are orange and subequal; syn- 
carps 6-7 cm long, 5-5.5 cm in diameter, ovoid 
to broadly ellipsoid, bearing about 160 drupes, 
these 21-22 mm long, 3.5-5 mm wide, 3-4 
mm thick, lower 34 oblanceoloid, upper l A 
subulate, 4—6-angled, the body sides smooth, 
later with exposed fibers; pileus 10-11 mm 
long, of a lower half narrowly conic-pyramidal, 
the surface smooth, sharply angled, the angles 
continuing along the stout subulate style form- 
ing the upper half, arcuate proximally; stigma 
3 mm long, linear, in a distal cleft running al- 
most to the apex; endocarp centering in lower 
l A, and 7-8 mm long, the walls pale, 0.3 mm 
thick; apical mesocarp a broad cavern 2 mm 
long; basal mesocarp fibrous up the sides, fleshy 
within. 
EXPANDED DESCRIPTION: Shrub to 5 m tall; 
stem with the leaf scars inconspicuous; prop 
roots 60 cm long; leaves to 2 m long, 4-5 cm 
wide, above clear green, below paler and glau- 
cous; foliage leaves little broadened at base, 
the margins beginning at 4 cm up with prickles 
1.6-2 mm long, 2-5 mm apart, stout subulate, 
ascending; the midrib below beginning at 9 
329 
