Ravenea beentjei

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Ravenea (rah-vehn-EH-ah)
beentjei (beh-ent'-ee)
1681399663.jpg
Madagascar. Photo by Dr. Mijoro Rakotoarinivo/Kew.
Scientific Classification
Genus: Ravenea (rah-vehn-EH-ah)
Species:
beentjei (beh-ent'-ee)
Synonyms
None set.
Native Continent
Africa
Africa.gif
Morphology
Habit: Solitary
Leaf type: Pinnate
Culture
Survivability index
Common names
None.

Habitat and Distribution

Endemic to Madagascar. Known only from Vondrozo forest, in southeast Madagascar.
Photo by Dr. Rakotoarinivo, Mijoro/Kew.
Common in lowland humid forest, in valleys and swampy areas; alt. 600-650 m.

Description

Medium-sized, solitary, dioecious palm. Trunk 3.5 - 10 m tall, 8- 15 cm in diam., internodes 4- 11 cm, bark brown, wood soft, base of the crown bulbous, about 11 cm across. Leaves 8- 15 in the crown, porrect to pendulous, arching, marcescent, occasionally trapping litter; sheath 50-90 x 10-15 cm, yellowish but covered with brown blackish indumentum, margins disintegrating and fibrous; petiole 30- 150 cm long, 3.5- 3.8 ? x 1.5-2 cm in cross section, slightly channelled, margins sharp, abaxial surface covered in caducous white to greyish tomentum; rachis 2 . 3.50 m long, 1.2- 2 ? x 2.2- 2.6 cm in cross section in mid-leaf, keeled, pale green, with irregular grey to brown tomentum, becoming glabrescent; leaflets stiff, regularly arranged, arranged in one plane, dark green, 46 . 55 on each side of the rachis, the proximal leaflets 52- 123 ?x 0.8- 2 cm, the median leaflets 116-124 ? x 4.8- 6 cm, the distal leaflets 21- 42 ? x 0.8- 2.9 cm, leaflets spaced 4-6 cm apart, abaxial surface with scattered brown scales and ramenta. Inflorescences interfoliar, solitary. Staminate inflorescence pendulous, branched to 2 orders, peduncle 24- 38 cm long, 0.8- 1 cm wide, prophyll not seen, peduncular bracts several but only 2 preserved, about 77 and 82 cm long, about 9 cm wide, purplish, covered in red brown tomentum, rachis about 48 cm long; rachillae 9- 15 cm long, about 0.5 mm wide; pedicel 0.6- 1.2 mm. Staminate flowers yellow, calyx connate for about 0.4 mm, lobes 1.6 -2 ?x 0.8- 1 mm; petals free, 6.2- 6.5 ?x 4.5- 4.7 mm, with scattered minute red dots near the apex; stamens (6) 12, 2 opposite each petal, and 2 opposite each sepal, filaments 0.4- 0.8 mm, anthers about 3.5 x 1.4 mm., pistillode minute. Pistillate inflorescence erect, branched to 1 order, peduncle 19- 25 cm long, about 1.6 cm across, yellowish, covered with red brown tomentum; prophyll about 30 x 8 cm, pinkish, covered with red brown tomentum; peduncular bractsc. 85x 6 cm, ± equal in size, purplish-pink, abaxial surface densely covered in red brown tomentum in the upper part; rachis 30-35 x 1.5- 1.7 cm, yellow but sparsely to densely covered with red brown tomentum, with 6 . 18 rachillae; rachillae 35- 48 cm long, glabrescent, sinuous, pedicels 3.7- 5.2 mm long. Pistillate flowers yellow, sepals connate for about 1.6 mm, lobes about 0.8 ? x 0.7 mm; petals unequal, spathulate, coriaceous, 1.3- 6.5 x 4.5 - 5.4 mm; staminodes 12, minute; gynoecium about 7.4 x 8 mm, gibbous, triloculate, stigmas recurved. Fruits blackish, subglobose, perianth persistent, stigmatic remains apical, 1.4- 1.6 x 1.5 - 1.6 cm, epicarp about 0.8 mm thick, mesocarp 1.8 mm thick, spongy, endocarp spongy. Seeds 3; 1.3-1.4 x 0.7- 0.8 mm, seedcoat black, 0.1 mm thick; endosperm homogeneous.(M. Rakotoarinivo and J. Dransfield. 2010)/Palmweb. Editing by edric.

Similar to Ravenea robustior and R. krociana in having solitary inflorescences whether in male or female plants but differing from these in the lack of a ventricose trunk, a more delicate inflorescence, with pendulous rachillae, and having staminate flowers with usually 12 stamens rather than six. The presence of three seeds in the fruit is also rather unusual. The specific epithet honours Henk Beentje, monographer of Ravenea and co-author of Palms of Madagascar (M. Rakotoarinivo and J. Dransfield. 2010)/Palmweb.

Culture

Comments and Curiosities

This is a dioecious genus.

Conservation: Critically Endangered [CR (B2a+b(iii); D)]. Known only from one population in Vondrozo, where it is restricted to frequently flooded areas. In an Extent of Ocurrence estimated to be less than 7 km2, only about 40 mature individuals have been recorded in the field. The forest of Vondrozo is managed by the local community but logging operations still occur. (M. Rakotoarinivo and J. Dransfield. 2010)/Palmweb.

This is a tillering palm, it exhibits saxophone style root growth (it has a heel), keep top third of heel above soil elevation!


Rakotoarinivo, M. & Dransfield, J. 2010. New species of Dypsis and Ravenea (Arecaceae) from Madagascar.


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).

M. Rakotoarinivo and J. Dransfield. 2010


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

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