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Các thứ của Paphiopedilum villosum ở Việt Nam

Cập nhật ngày 10/6/2010 lúc 6:18:00 PM. Số lượt đọc: 3432.

Paphiopedilum villosum is typically an integral element of mountain tropical forests of Indochina. Despite wide commercial collecting, this species remains relatively common in remote montane areas that are inaccessible to commercial collectors.


Map 1. Distribution of Paphiopedilum villosum varieties in Vietnam. Localities of studied taxa are marked on the map of Vietnam with red (P. villosum var. annamense), blue (P. villosum var. boxallii), pink (P. villosum var. fusco-roseum), green (P. villosum var. fusco-viride) and white dots (P. villosum var. villosum).

Natural conditions of its habitats in Vietnam were studied and reported in detail earlier (Averyanov et al., 2003, 2004; Averyanov, 2006). In the studied area this species commonly grows as a humus epiphyte on large mossy trees (Fig. 1). Sometimes, however, it is also occasionally observed as a typical lithophyte (Fig. 2) or even a terrestrial clustering herb that settles down on shelves of shady cliffs and bluffs, particularly along deep and narrow humid stream canyons. Recent field studies reveal remarkable variation of P. villosum in Vietnam, which may indicate this area as the richest center of genetic diversity for this taxon. At least five morphological variants of P. villosum are recognized in Vietnam. They differ distinctly from each other by the specific coloration of the median sepal. Form of tepals, size of flowers and other characters in each variant also vary widely, but coloration of the flowers remains the main separating feature for these races.

Although some taxonomists might distinguish these color variants at a lower taxonomical rank, I regard them as varieties until more detailed studies of the range of their variation can be completed. Below follows a key for their identification and a short illustrated survey of these intraspecific taxa as they occur in Vietnam.

Paphiopedilum villosum (Lindl.) Stein, 1892, Orchideenbuch: 490.

- Cypripedium villosum Lindl., 1854, Gard. Chron. (1854): 135.

Type: Burma, Lobb s.n. (Holotype – K-LINDL).

Key for Identification of P. villosum Varieties found in Vietnam

1. Median sepal broadly oblanceolate to narrowly obovate, boldly spotted with deep brown fused blotches, with strongly reflexed lateral margins throughout its length; petals often marked with purplebrown, narrowly spathulate, distinctly attenuate to narrowing stipitate base ................ 2. P. villosum var. boxallii

-. Median sepal obovate to suborbicular, without distinct spots, with strongly reflexed
lateral margins at lower part; petals without purple-brown marks, with more or less
broad, not distinctly stipitate base .............................................................................. 2

2. Median sepal dark brown with more or less wide yellowish-green to whitish
margin .................................................................. 5. P. villosum var. villosum

-. Median sepal light yellowish-green, dull pink to purple, or white with more or
less wide median longitudinal brown stripe ..................................................... 3

3. Median sepal white, with more or less wide median longitudinal brown
stripe, sometimes with broad dark brown central area occasionally
margining with green  ............................ 1. P. villosum var. annamense

-. Central area of median sepal dull pink to dark purple or dull yellowish
-green tinted with light brown along mid-vein ..................................... 4

4. Central area of median sepal dull pink to dark purple,
occasionally greenish at the base; sepal margin commonly
white ....................................... 3. P. villosum var. fusco-roseum

-. Median sepal dull yellowish-green, tinted with light brown along
mid-vein, occasionally with white or yellowish-white margin .........
.................................................... 4. P. villosum var. fusco-viride

1. P. villosum var. annamense Rolfe., 1907, Curtis’s Bot. Mag. 133, Tab. 8126.

Lectotype: Annam, Micholitz s.n., cult. Sander (icon in Curtis’s Bot. Mag. 133, Tab. 8126).


Fig. 3, 4. Typical forms of P. villosum var. annamense growing as a humus epiphyte in its natural habitat. These plants have a white median sepal with a narrow dark brown longitudinal stripe along mid-vein.
© L. Averyanov

 


Fig. 5. The form of P. villosum var. annamense with median sepals bearing a broad median brown stripe margining with green. Such plants exhibit the tendency of certain deviation toward the type variety.
© L. Averyanov


Fig. 1, 2. Paphiopedilum villosum growing as a humus epiphyte (fig.1) and lithophyte (fig. 2) on bluffs of stream canyons in the mountains of southern Vietnam.
© L. Averyanov

Typical flowers of this variety have a pure white median sepal with a narrow chestnut-brown longitudinal stripe (Fig. 3, 4). Often the central brown stripe in flowers of this taxon become wider forming a broad chestnut to brown-purple central area margined with green (Fig. 5). This tendency indicates a certain deviation of some plants towards the type variety that makes the relationship of both taxa unclear. Field observations give some evidence that plants that fit with the description of P. villosum var. annamense dominate in mountain regions of the southern Vietnam and may be endemic for that area (map 1). Plants of this variety were observed growing mostly as typical humus epiphytes. The suggestion that this variety differs from the type in narrower suberect leaves and in smaller flowers (Cribb, 1998) was not confirmed by analysis of large wild material. Variation of both mentioned features is very considerable and thus can be hardly used for discrimination between these taxa.


Fig. 6-8. These common variants of P. villosum var. boxallii supposedly originated from montane areas of Hoang Lien Son Range in northwestern Vietnam and were cultivated in local nurseries in this region.
© L. Averyanov

2. P. villosum var. boxallii (Reichenb.f.) Pfitzer, 1903, in Engler, Pflanzenr. 4, 50, 12, Orch. Pleon.: 73.

Cypripedium boxallii Reichenb.f., 1877, Gard. Chron. n.s. 7: 367.

Type: Burma, Moulmein, Boxall s.n. (Holotype – W). This variety described from Myanmar is a remarkable variant readily distinguished by its deeply colored flowers with a boldly spotted narrow dorsal sepal. A number of such plants are cultivated in local orchid nurseries of northwestern Vietnam. Most of them were said to have been collected on granite cliffs of the Hoang Lien Son range between 1500-2200m (4900-6600 ft.) (map 1). However, we have not seen this rare taxon growing in natural conditions. Morphological variants of plants supposedly originating from this area and cultivated here in private local nurseries may be seen on Fig. 6-8.


Fig. 9. Type specimen of P. villosum var. fusco-roseum. (Photo: Prof. Phan Ke Loc; digital correction: L.Averyanov)


Fig. 10, 11. The median sepal in some forms of P. villosum var. fusco-roseum are flushed with greenish tint at the base.
© L. Averyanov

3. P. villosum var. fusco-roseum Aver., 2002, Komarovia 2: 17.

Type: S.Vietnam, Gia Lai prov., Chu Pah distr. 27.05.2001, Phan Ke Loc, P-9845A (Holotype - HN, photo - LE). P. macranthum Z. J. Liu and S. C. Chen, 2002, Acta Bot. Yunnan., 24, 6: 712.


Fig. 12. Rather marginal form of P. villosum var. fusco-roseum with deep purple center of median sepal. Similar plants were described from Cambodia under the name P. macranthum.
© L. Averyanov


Fig. 13. Type specimen of P. villosum var. fusco-viride. (Photo: Prof. Phan Ke Loc; digital correction: L.Averyanov)

Type: Cambodia. Eastern part, no precise locality, 2001.11.06, Z. J. Liu (Holotype – Herbarium, Shenzhen City, Wutongshan Nursery). These plants have remarkable flowers with pink to purple centers of the dorsal sepal bordered with a pure white margin (Fig. 9-12). Occasionally the pink central area of the sepal is tinted with light green at the base (Fig. 11). In other variants, the whole flower may be a light dull yellowish color with a nearly white dorsal sepal that is slightly tinted with pink, which was observed in type specimen (Fig. 9). Another marginal form of this taxon has the dorsal sepal with a deep purple central area margined with wide pure white border (Fig. 12). Such plants were recently described as P. macranthum on the basis of plants imported from eastern Cambodia bordering Vietnam (Z. J. Liu, S. C. Chen, 2002). Available data indicate distribution of P. villosum var. fusco-roseum in a narrow mountain area spreading along the Vietnamese border with Laos and Cambodia (map 1). This rare variety is obviously a local endemic of eastern Indochina not yet reported from other areas of the peninsula. A few of the observed plants of this taxon were found as lithophytes or terrestrial herbs and were flowering from October to December.

4. P. villosum var. fusco-viride Aver., 2002, Komarovia 2: 17.

Type: S. Vietnam, Gia Lai prov., Chu Pah distr. 27.05.2001, Phan Ke Loc, P-9845B (Holotype - HN, photo - LE).


Fig. 14-16. Common variants of P. villosum var. fusco-viride. © L. Averyanov

Flowers of this variety are wholly dull yellowish with a dull yellowish-green dorsal sepal barely tinted with brown as is observed in type specimens (Fig. 13). Other studied individuals have similar coloration of their flowers with a more or less pronounced brown tint at the center of the dorsal sepal (Fig. 14-16). Increasing intensity of the brown color at the center of the dorsal sepal, in some observed specimens, approaches the type variety, which in Vietnam is rather uncommon. Distribution of P. villosum var. fusco-viride in Vietnam is probably similar to the previous variety (map 1). This taxon may be found in Laos and Cambodia in regions close to the Vietnamese border. It also commonly grows as lithophytic or terrestrial herbs and flowers from October to December.

5. P. villosum var. villosum.


Fig. 17. Typical form of P. villosum var. villosum is relatively rare in Vietnam.
© L. Averyanov

The type variety with a green dorsal sepal and a large dark chestnut-brown central area is rather rare in Vietnam (Fig. 17). The vast majority of specimens found in this area more or less distinctly allied to P. villosum var. villosum usually bear some transitional features between this variety and var. annamense. The median sepal of such plants is distinctly bordered with a more or less wide white margin (Fig. 18, 19), or the sepal may even lack the green coloration (Fig. 20). The last mentioned plants closely approach P. villosum var. annamense, which is much more common at least in southern Vietnam. In Vietnam P. villosum var. villosum plants were found both as epiphytes and lithophytes. According to our observations, all varieties recognized here are morphologically connected to each other with numerous transitional forms and most probably are capable of producing fertile forms from any crossing combinations. The very restricted local endemism typical for mountain regions of Indochina is ancient and probably led to the formation of studied taxa. In this case geographic and topographic isolation in the wild is sufficient to maintain the genetic stability of their populations. On the basis of these studies of locally endemic forms of P. villosum it may be expected that in the future some other interesting endemic forms of this species will be found, particularly in territories of Laos and Cambodia, which still remain botanically unexplored.


Fig. 18-20. Variants of P. villosum var. villosum, which exhibit obvious morphological deviation toward var. annamense.
© L. Averyanov

Acknowledgements

Field and laboratory studies, results of which are presented in this paper, were made under the auspices of these exploration programs: "Population studies of endemic Paphiopedilum species in northern Vietnam" American Orchid Society, 2001-2002; "Discovery of endemic orchid flora in remote limestone areas of Northern Vietnam" American Orchid Society, 2004; “Exploration of rocky limestone flora and vegetation in Bac Kan province, northern Vietnam” U.S.A. National Geographic Society,2004, and investigation program of Vietnamese Botanical Conservation Program supported from Henry Luce Foundation (U.S.A.).

References

Averyanov L., Cribb, P., Loc, P. K., and N. T. Hiep. 2003. Slipper Orchids of Vietnam. With an Introduction to the Flora of Vietnam. Royal Botanic Gardens, Kew. Compass Press Limited.

Averyanov L. Cribb P., Loc, P. K., and N. T. Hiep. 2004. Lan Hai Viet Nam. Giao Thong van tai Publishing house. Ho Chi Minh City (Vietnamese ed., 2003).

Averyanov L. V. 2006. Paphiopedilum x cribbii (P. appletonianum x P. villosum), new natural hybrid from the territory of southern Vietnam. Orchids. 75:457-461. Liu Z. J., and S.C. Chen. 2002. Paphiopedilum macranthum, a New Species of Orchidaceae from Cambodia. Acta Bot. Yunnan. 24:712 – 714.

Leonid V. Averyanov
Herbarium, Komarov Botanical Institute of the Russian Academy of Sciences

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