Dypsis arenarum

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Dypsis (DIP-sis)
arenarum (ahr-eh-NAHR-uhm)
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Andasibe - Mantadia - Madagascar (2015) - East Coast of Madagascar. Photo by Tim Brian-IPS Newsletter.
Scientific Classification
Genus: Dypsis (DIP-sis)
Species:
arenarum (ahr-eh-NAHR-uhm)
Synonyms
None set.
Native Continent
Africa
Africa.gif
Morphology
Habit: Clustering
Leaf type: Pinnate
Culture
Survivability index
Common names
Hirihiry, Sand Palm.

Habitat and Distribution

Dypsis arenarum is endemic to Madagascar, between Soanierana-Ivongo, and Vatomandry.
ële Sainte-Marie, Madagascar. Photo by Dr. John Dransfield, Royal Botanic Gardens, Kew/Palmweb.
Littoral forest near fresh water; alt. 1-15 m.

Description

We are working on getting this species sorted out. There's an ongoing discussion HERE. We could use some help with this one.

Clustering palm in tufts of five or so. STEMS 5-6 m. tall, 6.5 cm in diam.; internodes 6-8 cm.; bark dark green, on older trunks brown; wood quite hard, slightly pinkish, moist. Crown holds 8-10 leaves , porrect, slightly arched distally, with opposite leaflets at an angle of roughly 140° +-, with each other; sheath 20-47 cm., whitish green to pale yellow-brown abaxially and distally, with wax and scattered reddish scales, reddish brown and glabrous adaxially, turning into the petiole after a small sharp bend, but without obvious ligules; petiole 60-72 cm., 1.8-2 x 1.5-1.6 cm. proximally, 1.5 x 1.2 cm. distally, channelled with sharp edges, pale brown with minute scattered scales; rachis 1.5-1.7 m., in mid-leaf 0.9-1.6 x 0.7-1.2 cm., keeled, pale brown with minute scattered scales to glabrescent; leaflets 28-30 on each side of the rachis, regular, stiff and straight, pendulous in their most distal part, the proximal 81-129 x 0.9-2.5 cm., median 67-80 x 2.2-3.6 cm. (interval 4-6.5 cm.), distal 16- 36 x 0.9-2.1 cm., the terminal pair not or hardly (up to 0.5 cm.) joined and with briefly (about 0.3 cm.) truncate and dentate apices, apices of median leaflets unequally bifid for 2-3 cm. and attenuate, glaucous, with tufts of large redbrown ramenta to 4 mm. long proximally and abaxially on the midrib, and with many minute scattered scales on the veins (invisible in Guillaumet 2527), main veins 1-5, faint; young leaves reddish. INFLORESCENCE interfoliar, the part outside the leaf sheath arching through 180°, branched to 2 orders; peduncle 34-57 cm. long, proximally about 2 x 0.5 cm., distally 1.5-2.3 x 0.6-1.2 cm., distally with scattered scales, glabrescent; prophyll 42-75 cm. long and 4-5.5 cm. wide, borne at 5-17 cm. above the base of the peduncle, open for 16-25 cm., and hooded distally with an acute apex, coriaceous, slightly waxy, abaxially pale brown with scattered scales, adaxially red-brown and glabrous; peduncular bract inserted at 27-34 cm. from the base of the peduncle, 39-53 cm. long, not or hardly beaked, split over its entire length or closed in the distal part, distally hooded and 12 cm. wide, pale brown with scattered scales, not deciduous but remaining contiguous with the prophyll, for the most part and similar to the prophyll; non-tubular peduncular bracts near the apex of the peduncle, 1.3-2 cm. long, triangular, acute; rachis 11-28 cm. long, glabrous, with 5-14 branched and 12-20 unbranched first order branches; first order branches subtended by rachis bracts to 1 x 0.5 cm., with a secondary rachis of up to 6 cm. long and with flattened base 9-17 x 3-8 mm. and with 2-8 rachillae; rachillae porrect, 10-31 cm, 2-4 mm in diam., with rather dense triads in slight pits and with distinct, entire, triangular, acute rachilla bracts. STAMINATE FLOWERS with sepals 2-2.2 x 1.8-2 mm.; petals connate for c. 0.5 mm., 3.1-3.4 x 1.9-2 mm.; stamens 6, slightly unequal with the antepetalous ones with filaments slightly wider at the base, filaments 1.6-2 mm. long and cylindrical, anthers 1.8-2 x 0.6 mm., the locules parallel and obtuse, dorsifixed and versatile; pistillode about 2.4 mm. high, 0.6 mm in diam. PISTILLATE FLOWERS with sepals 2.7-3 x 2.4-3.4 mm.; petals 3.5-4.2 x 3-4 mm.; staminodes 0.6-0.8 mm., flat; gynoecium 3.2-3.6 x 2.9-3 mm. FRUIT ovoid to ellipsoid with a rounded apex, 10-12 x 8-9 mm., with anastomosing fibrous endocarp. SEED slightly obovoid with rounded apex and apiculate base, 8-9.5 x 5.5-6 mm., with subaequatorial depression; endosperm homogeneous. (J. Dransfield and H. Beentje. 1995)/Palmweb. Editing by edric.

Differs from D. lutescens (which occurs in the same localities, in the same habitat) in the longer petiole, the smaller number of leaflets, the longer petals and the more robust rachillae; the inflorescence branches to 2 orders, while in D. lutescens it usually branches to 3 orders (but occasionally is branched to 2 orders). From D. psammophila it differs in the generally larger leaves (petiole, rachis, leaflets) with many scattered scales; the much longer prophyll and stouter rachillae. (J. Dransfield and H. Beentje. 1995)/Palmweb.

Culture

Sunny, moist, but well drained position. Easy to cultivate. Cold Hardiness Zone: 10a

Comments and Curiosities

This species can easily be confused with D. lutescens, which grows in the same area, but has a longer petiole and fewer leaflets; the seed is also much smaller. The name means 'of the sands', since the species occurs on sand near the sea. (J. Dransfield and H. Beentje. 1995)/Palmweb.

Conservation: Critical. The distribution area is small, the numbers of this species are thought to be very low, and the vegetation type is threatened by development and fires. (J. Dransfield and H. Beentje. 1995)/Palmweb.

While generally similar to Dypsis lutescens, this critically endangered palm from coastal forest in eastern Madagascar is distinguished by its longer leafstalks, fewer leaflets and much smaller seeds. As adaptable and robust as the well known Golden Cane Palm, it will thrive under the same general conditions. (RPS.com).

As can be seen from the photos, there are apparently several palms correctly or incorrectly identified as D. arenarum. Palmpedia has chosen to post them all, while acknowledging that several are probably in error. When the identities are more securely recognized, we will make the necessary corrections.


External Links

References

Phonetic spelling of Latin names by edric.

Special thanks to Geoff Stein, (Palmbob) for his hundreds of photos.

Special thanks to Palmweb.org, Dr. John Dransfield, Dr. Bill Baker & team, for their volumes of information and photos.

Glossary of Palm Terms; Based on the glossary in Dransfield, J., N.W. Uhl, C.B. Asmussen-Lange, W.J. Baker, M.M. Harley & C.E. Lewis. 2008. Genera Palmarum - Evolution and Classification of the Palms. Royal Botanic Gardens, Kew. All images copyright of the artists and photographers (see images for credits).

Dransfield, J. & Beentje, H. 1995. Palms of Madagascar. Royal Botanic Gardens, Kew and The International Palm Society.


Many Special Thanks to Ed Vaile for his long hours of tireless editing and numerous contributions.

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