Pandanus macrophyllus Martelli

Callmander, Martin W. & Laivao, Michel O., 2003, New findings on Pandanus sect. Imerinenses and sect. Rykiella (Pandanaceae) from Madagascar, Adansonia (3) 25 (1), pp. 53-63 : 56-58

Pandanus macrophyllus Martelli

Webbia 2: 437, fig. 1 K, L (1907) ; Martelli & Pichi- Sermolli, Mém. Inst. Sci. Madagascar, Sér. B , Biol. Vég. 3: 155 (1951); Stone, Webbia 24: 588 (1970); Stone , J . Linn. Soc., Bot. 63: 107, 124 (1970); Guillaumet, Webbia 28: 506 (1973). Stone, Bot. Jahrb. Syst. 94: 511 (1974). — Type: Rollot 11, Madagascar, Imerina province, 1906 (holo-, FI!) .

Tree <6-7 m tall, trunk prickly, 18-25 cm in diameter, erect, dichotomously branched; prop roots few or none. Leaves flagellate, the one from the apex of the trunk as long as the lateral ones, 330-351 cm long, 15-17 cm wide in the middle, 16 cm near the sheath, terminated by a flagellum 7.5 cm long, 1-3 mm wide; dry leaves coriaceous; leaf pleat unarmed; longitudinal and transverse veins visible on both sides; prickles yellowish; marginal prickles beginning at 35 cm above the base and extending to the apex, antrorse, in the lower third <7 mm long, 5 mm apart, in the mid third <5 mm long, 7-10 mm apart, in the distal third <3 mm long, apart 3 mm; midrib armed from 70 cm to the apex, midrib prickles smaller than the marginal prickles at the same height; sheath 35 cm long, 16 cm wide at apex, 20 cm at base. Infrutescence terminal, plurisyncarpic, 8 syncarps, progressively smaller from the base to the apex, 9.7-10 cm long, 6.9-7.3 cm wide, ovoid, triangular-obtuse in transverse section; core 5.5-7 cm long, 2-3 cm wide; peduncle 95- 105 cm long, 4 cm wide at apex, 2 cm in the middle, curved, trigonous, veins visible. Drupes wider in the apical and basal part of the syncarp, connate in the mature syncarp, 25-30 mm high, 8-13 mm wide, 3-8 mm thick, 1/7 superior free; pileus with prominent angles, dome-like, 2 mm high; stigmas (2-)3, spiniform, 8 mm high, 1.1 mm thick at base, oblique, turned towards the summit of the syncarp; endocarp 1.3 cm long, 1.5 mm wide, 1 mm away from the stigmas; seed locule oblong, 11 × 1 mm, apex 1 mm from the base of the stigmas, superior mesocarp narrow and fibrous; inferior mesocarp thick and fibrous.

MATERIAL STUDIED. — MADAGASCAR: Callmander, Laivao & Wohlhauser M041 , 16 km from Brickaville on the RN2 to Antananarivo, 18°52’08’’S, 48°59’42’’E, 19 Aug. 1997 ( G, NEU, TAN, P); Rollot 11, Imerina province, 1906, type ( FI); Stone 7848, between Moramanga and Anosibe-Anala, North of the chute de la mort, 18 Mar. 1968 ( KLU, P, BISH) .

NOTES. — This species grow along the east coast of Madagascar: in lowland primary forest, often along streams, 300-600 m ( Fig. 1 ). Its vernacular name is Vakoandrano in the Betsimsaraka language .

Pandanus macrophyllus (sect. Rykiella ) is very interesting from the point of view of understand-

ing the origin and speciation of the Malagasy endemics.

Pandanus macrophyllus was first described by M ARTELLI in 1907. It was assigned by MARTELLI & PICHI- SERMOLLI (1951) as the

type of a new section Rykiella by P ICHI - SERMOLLI in order to point out its affinities with the sect. Rykia . The type specimen (Rollot 11) is based on an immature syncarp, 3-4 cm long and 2.5-3.5 cm wide on a peduncle 20 cm long ( Fig. 5D ) (M ARTELLI 1907), whereas mature syncarps of this species are up to 10 cm long and 7 cm wide ( Fig. 4A (a)) and the peduncle is up to 100 cm long (cf. Callmander et al. M041). The prescence of such a long peduncle is known in another Malagasy species: P. longissimepedunculatus Martelli (MARTELLI & PICHI- SERMOLLI 1951: 159, fig. 29a). When P ICHI -S ERMOLLI described Pandanus sect. Rykiella , he also included P. longissimepedunculatus and distinguished it on the basis of syncarp and drupe size and a peduncle length (20 cm in P. macrophyllus vs. 120 cm in P. longissimepedunculatus ). HUYNH (1979a) transferred P. longissimepedunculatus to sect. Phaenops based on its micromorphology, drupes morphology and habit, an interpretation supported by the fact that P. longissimepedunculatus has thin, long, deciduous stigmas ( Fig. 4C ). Furthermore, this species is never branched ( Fig. 5A ) and conforms to the Corner architectural model ( GUILLAUMET 1973). The micromorphology of leaves is distinctive, with a clear zonation of the stomata on the abaxial face ( HUYNH 1979a) and the papilla belong to class I according to HUYNH’ s (1974) classification ( Fig. 6A ) instead of the class IIb papilla found in P. macrophyllus , characterized by the absence of zonation of stomata and simple papilla ( Fig. 6B ) ( HUYNH 1974). For these reasons, HUYNH (1979a) was correct to remove P. longissimepedunculatus from sect. Rykiella . Although there is a broad affinity between P. macrophyllus and P. longissimepedunculatus — they are tall trees with thick trunks (compare Figs. 5A and 5B ), large and rough leaf-crowns, and a long peduncle ending in numerous ovoid syncarps ( Figs. 4A (b), 4A(c) and 5C) — similarity stops here. Pandanus macrophyllus is a large dichotomously branched tree ( Fig. 5B ), with an infrutescence caracterized by a thick, straight peduncle ( Fig. 5C ) bearing about 8 subspherical heads, and its drupes are 2-3 celled with 2-3 non-deciduous thick stigmas ( Fig. 4B ), whereas P. longissimepedunculatus is a large monocaule tree ( Fig. 5A ), with an infrutescence bearing about 5-6 subspherical heads, and its drupes are one celled with one thin, long and deciduous stigmas ( Fig. 4C ).

Figures

Fig. 1. — Map of Madagascar showing collection localities of members of Pandanus sect. Imerinenses (grey) and sect. Rykiella (black square). Major towns are indicated by a black circle.

Fig. 5. — Pandanus longissimepedunculatus (A) and P. macrophyllus (B-D): A, architecture showing pendant infrutescences and non-ramified habit (scale bar = 1 m); B, architecture showing pendant infrutescence and branched habit (scale bar = 1 m); C, close up of a mature infrutescence, from Callmander et al. M041 (scale bar = 10 cm); D, young infrutescence, from the type specimen Rollot 11 (scale bar = 5 cm).

Fig. 4. — Pandanus macrophyllus (A,B), from specimen Callmander et al. M041 and P. longissimepedunculatus (C), redrawn after STONE (1974): A(a-c), syncarp lateral view (a), longitudinal section showing the core in the middle (b) and transverse section showing spherical shape (c); B, lateral view of a drupe showing two spiniform stigmas; C, lateral view of a drupe showing long and thin spiniform stigma.

Fig. 6. — LM (light microscopy) view of stomata on abaxial leaf surface (A-C) (scale bars = 20 µm) and SEM (scanning electron microscopy) of pollen and staminate flowers (D-F): A, stomata of Pandanus longissimepedunculatus showing papillae (Laivao et al. M034); B, stomata of Pandanus macrophyllus showing papillae (Callmander et al. M041); C, stomata of Pandanus imerinensis showing dendritic ramifications of papillae (Callmander & Bemandiny M122); D, spinulate pollen of Pandanus imerinensis (Callmander & Bemandiny M0122), scale bar = 5 µm; E, staminate flower of Pandanus imerinenses showing the candelabra-like disposition of stamens, scale bar = 2 mm; F, close up of a mucronate anther, scale bar = 500 µm (Callmander & Bemandiny M122).