Rhapis puhuongensis
| Rhapis (RAH-pis) puhuongensis (poo-hoo-ohn-GEHN-sis) | |||||||
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 Rhapis puhuongensis, a new palm species from Vietnam, described by Garden scientist Dr. Andrew Henderson and colleagues M. Trudgen and T. T. Phuong Anh. | |||||||
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Contents
Habitat and Distribution
Rhapis puhuongensis is found in North Central Vietnam, Nghe An Province, in low
Description
Dwarf clustering fan palm. Stem slender, to 1.2 m tall, 5–8.0 mm in diam., 3.4–4.4 mm in diam. without sheaths, internodes 13–30 mm long, nodes distinct, tattered remnants of leaf sheath persistent on upper stem, terminating in a crown of 9–12 (15) leaves. Leaf sheath closely sheathing the stem, to 7 cm long, forming a mesh of narrow fibers; ligule papyraceous, 10–15 mm long, often persistent at maturity; petiole slender, 1.2–1.6 mm wide, 12–16 cm long when mature, margins minutely toothed; leaf blade acutely to obtusely deltoid in outline, up to 13.5 cm from petiole apex to tip, folds 14–15, undivided for 2–4.5 cm, then splitting between the folds into 13–15 linear segments, each segment 8–11 cm long, 3–6 (9) mm wide, mildly cucullate, usually with one fold except a central segment with two folds, segment margins scabrid, segment apices split along and between folds to form shallow teeth, small (about 0.5 mm) caducous hair-like scales scattered on adaxial and abaxial folds (primarily near the petiole), transverse veinlets conspicuous; adaxial hastula small, semi- circular, 1 × 1 mm, densely tomentose on young leaves, glabrous on mature leaves, abaxial hastula absent. Inflorescences interfoliar, up to 5 per stem, slightly pendulous, to 24.5 cm (from point of attachment to stem), branched to 2 orders, with a primary branch bearing 2–4 rachillae within each of 3 rachis bracts; prophyll tubular, 9–14 cm (exserted from sheaths for 3–7 cm), 2 keeled, sheathing, sometimes with indument along the keels, splitting along abaxial side, overlapping the start of the first rachis bract; rachis bracts (2) 3, overlapping, tubular, 2–6 cm, sometimes with an incomplete distal rachis bract, occasional scattered indumenta, tomentose at tip, split 1/3–1/2 length from tip; peduncle 8–10 cm, 2/3 within sheaths; rachis to 12.5 cm (elongating to 22 cm in fruit), slender, 0.7–1.1 mm diam.; rachillae to about 19 mm (elongating to 67 mm in fruit), 0.3–0.6 mm in diam., peachy-pink, dark brown when dry, with pale caducous indumenta, each rachilla with 18–20 shortly pedicellate flowers, 0.5–2.2 mm apart (elongating to 1.2–7 mm apart in fruit); pedicels 0.2 × 0.4 mm (elongating to 0.8 × 0.6 mm in fruit), subtended by an elongate triangular bract. Flowers unisexual. Male flowers not seen. Female flowers appearing hermaphroditic, with well developed gynoecium and staminodes, subtended by an elongate triangular bract, pedicels 0.2 × 0.4 mm (0.8 × 0.6 mm in fruit), proximal flowers obovoid grading to spherical at the rachilla tip, 1.65 × 3 carpels developing, apocarpus, each carpel asymmetrically conic, flattened adaxially with an abaxial bulge, 0.25 × 0.075–0.2 mm. Fruit ovoid to spherical, green when immature, yellow or white when mature, to 6 × 4.5 mm, 1–3 carpels maturing, borne on a receptacular- stalk to 4.1 mm. (A New Species from Vietnam by Dr. Andrew J. Henderson 2008) Editing by edric.
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Taxonomic discussion: The leaves of Rhapis are unusual amongst palms because they are divided into segments between, rather than along, the folds in the leaf. The presence of this type of leaf splitting in our new species, together with distinctive floral characteristics (such as the fusion of the anther filaments to the petals), clearly place it within Rhapis. The distinctive leaves allow this species to be easily distinguished from other Rhapis species because they are small, have an unusual deltoid outline, are undivided for 2–4.5 cm and are then divided into mostly single-fold segments. At a maximum of 13.5 cm, the leaf blade is at least 4.5 cm smaller than other known Rhapis species. This species seems to most closely resemble Rhapis vidalii Aver., T.H.Nguyên & P.K.Lôc, another dwarf understory palm, which was recently described and is distributed in north- central Vietnam (Fig. 6). Vegetatively they are easily distinguishable because the leaves of R. vidalii are at least 1/3 larger, are suborbicular in outline and the blade is segmented from near the base (Averyanov et al. 2006). The division of the leaves into predominantly single fold segments is shared by both species, but is otherwise unknown within Rhapis. The species can be distinguished florally as the inflorescence structure of R. puhuongensis is more robust and less pendulous than the lax inflorescences of R. vidalii. The corolla of the available flowers of R. puhuongensis is almost entirely enclosed within the calyx whereas the corolla of R. vidalii is exserted above the calyx for 3-5 mm. The fruit of both species are borne on a receptacular-stalk, the similarities of which suggest that the corolla of mature R. puhuongensis flowers may be exserted in a similar fashion to those of R. vidalii. Only one carpel normally develops into a mature fruit in R. vidalii, whereas two or three often develop in R. puhuongensis. (A New Species from Vietnam by Dr. Andrew J. Henderson 2008) Rhapis was described by Uhl and Dransfield (1987) as being dioecious or polygamous and by Hastings (2003) as dioecious or rarely hermaphroditic. A recent study of Rhapis floral morphology (Giddey 2007) found only one instance of hermaphrodite flowers, in some, but not all flowers of Rhapis laosensis Becc. Morphologically, the female flowers of R. puhuongensis, which have well developed staminodes, appear to closely resemble the hermaphrodite flowers of R. laosensis. In the hermaphrodite flowers studied by Giddey (2007), the stamens sit within the petals, above and without touching the gynoecium. The staminodes of this species sit in a similar position, although in this case they do appear to touch the gynoecium. The staminodes of typical female flowers in Rhapis (e.g., R. excelsa (Thunb.) Henry) sit between the gynoecium and the corolla, only rarely curving around above the gynoecium (Giddey 2007). We initially interpreted our flowers with their well- developed staminodes as hermaphroditic, however on further investigation no viable pollen grains were located. This is possibly due to the flowers available for study being somewhat immature, but nonetheless means that we feel it most appropriate to describe the flowers as being unisexual, only appearing to be hermaphroditic. (A New Species from Vietnam by Dr. Andrew J. Henderson 2008) |
Culture
Cultivation: Various species of Rhapis have been in cultivation since the 17th Century, and they are widely regarded as easily cultivated (Hastings 2003). We believe this species could become highly desirable, most probably as a container plant, due to its small ornamental leaves and lovely peachy-pink inflorescences (Figs. 1, 3 & 5). A small number of individuals have been transplanted and are in cultivation at IEBR, where they are doing well. (A New Species from Vietnam by Dr. Andrew J. Henderson 2008)
Comments and Curiosities
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Etymology: The species is named after the type locality, Pu Huong Nature Reserve. Conservation status: Data deficient. It is not possible to give a precise conservation status at present, due to limited information on range and habitat. The only fertile population located by the authors was growing near a path regularly used by local people, as access between their homes and Quy Hop. The vegetation was already degraded and although some protection may be provided by staff from the Pu Huong Nature Reserve, who are actively revegetating the area, there is certainly a risk that this location will become too disturbed for the palm to persist. Another small population was located nearby (approx. 7 km), in severely degraded vegetation near fields and with much human activity. The status of the population at Pu Mat is unknown. (A New Species from Vietnam by Dr. Andrew J. Henderson 2008) Rhapis puhuongensis, a fan palm recently discovered in central Vietnam, is described as new. This beautiful palm, with its slender stem and dwarf habit, is distinctive in the unusual outline of the leaves, which are undivided for 2–4.5 cm and have linear segments. (A New Species from Vietnam by Dr. Andrew J. Henderson 2008) Morphological and Molecular Revision of Rhapis. When putting together his groundbreaking volume Palms of Southern Asia, Garden scientist Dr. Andrew Henderson was surprised at how little was known about the genus Rhapis. This group of small Southeast Asian palms includes the beautiful and commonly cultivated Lady palm (Rhapis excelsa). Led by Dr. Henderson, the project is filling in gaps of knowledge about Rhapis through extensive fieldwork with Southeast Asian colleagues to explore and understand the various species, their distributions, and economic uses. A combination of morphological (i.e., form and structure) and molecular analysis is determining evolutionary relationships of species within the genus Rhapis, and Rhapis' relationships to other palm genera. (Southeast Asia Program By Dr. Andrew J. Henderson) |
- IMAGE GALLERY
Rhapis puhuongensis, a new palm species from Vietnam, described by Garden scientist Dr. Andrew Henderson and colleagues M. Trudgen and T. T. Phuong Anh.
Rhapis puhuongensis, a new palm species from Vietnam, described by Garden scientist Dr. Andrew Henderson and colleagues M. Trudgen and T. T. Phuong Anh.
Photo by Paul Craft.
Photo by Paul Craft.
External Links
- Glossary of Palm Terms
- MODERN BOTANICAL LATIN
- "Just To Be Clear"
- Rhapis puhuongensis, A New Species from Vietnam by Dr. Andrew J. Henderson 2008
- Southeast Asia Program by Dr. Andrew J. Henderson
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.
A New Species from Vietnam by Dr. Andrew J. Henderson 2008. 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).
Many Special Thanks to Ed Vaile for his long hours of tireless editing and numerous contributions.
