Paphiopedilum x cribbii (Orchidaceae, Cypripedioideae), a new natural hybrid from Southern Vietnam

Paphiopedilum appletonianum and Paphiopedilum villosum are fairly common even now in montane areas of southern Vietnam at elevations of 1,500–2,200 m (4,900–7,200 feet) (Fig. 1). Both species commonly grow there in humid, closed, montane, evergreen and broad-leaved forests (Fig. 2, page 458) and often are observed in the same habitats forming sympatric populations with numerous individual clumps. Though P. appletonianum is usually terrestrial whereas P. villosum is an epiphyte, both species are occasionally found as lithophytic or epiphytic herbs (Fig. 3, page 458) growing together at close proximity to each other. A difference in flowering time is probably an important isolating mechanism to prevent hybridization between these species in nature. Usually, in southern Vietnam, P. appletonianum flowers in spring, but P. villosum flowers in winter. Nevertheless, occasional flowers of the latter species may be observed during the spring and even in early summer (Averyanov et al., 2003). This suggests the possibility of natural hybridization between P. appletonianum and P. villosum in the area of their mutual distribution (Fig. 4, page 459). In this connection, the discovery of such a hybrid in a montane regions of southern Vietnam where both parental species are fairly common and occasionally abundant was not too surprising. The description of a new natural hybrid (P. appletonianum × P. villosum), named in honor of Phillip Cribb, PhD, as Paphiopedilum ×cribbii, follows.

Fig. 2. Montane, wet, mossy, closed, evergreen, broad-leaved and coniferous, primary forests on shale, sandstone and granite at elevations 2,000 m a.s.l. (6,500 feet) are the usual home of Paphiopedilum appletonianum and P. villosum in southern Vietnam.

Fig. 3. Typical habitat of large sympatric populations of Paphiopedilum appletonianum and P. villosum in montane forests in southern Vietnam at an elevation of 1,800–2,000 m a.s.l. (5,800 –6,500 feet), where their natural hybrid, P. ×cribbii,  arose.

Paphiopedilum ×cribbii Aver., nat. hybrid nov. (P. appletonianum [Gower] Rolfe × P. villosum [Lindl.] Stein.). Folia distincte tesselata; sepalum dorsale ovatum, viride, basi brunneum; petala obovata, purpureo-violacea; labium opacum roseolo-brunneum; staminodium late obovatum, apiculatum, opacum flavescenti-olivaceum, umbone humili viridi.

Type: VIETNAM, Lam Dong Prov., Dalat City area, 11º59’N, 108º22’E, 1,400–1,500 m (4,600–4,900 feet). Terrestrial herb. Flowers odorless, sepal and synsepal green with broad deep brown stripes joined at the base, sepals violet, violetgreenish toward the base, lip dirty light violet-green, staminode olive-green with bright green umbo. Leaves distinctly dull tessellated. Very rare. November 14, 2005. L. Averyanov & P.K.Loc. HAL 8626 (holotype, HN, photo., LE).

Fig. 4. Paphiopedilum appletonianum in wet, shady and humid conditions of rocky canyons formed by streams and waterfalls. It very often grows as a lithophytic clustering herb on vertical mossy cliffs.

Fig. 5. Paphiopedilum appletonianum in wet cloudy mountain forests on tops of ridges may occasionally be found as a typical humus epiphyte growing on old mossy trees, particularly at the base of their large boles.

Terrestrial herb. Leaves 5–7, oblong elliptic acute at apex, 12–18 cm long, 2.5–3.5 cm wide, finely quite distinct green/pale-green tessellated above, with pure green lower surface. Inflorescence 1-flowered; peduncle erect or suberect, green, deep purple-violet pubescent, 22–30 cm long. Flower bract ovate to elliptic, obtuse or acute, 2-2.2 cm long, 0.8–1 cm wide, green, deep purple-violet ciliated. Flower of middle size, 9–11 cm across. Dorsal sepal ovate to broadly ovate, obtuse, 3.4–3.8 cm long, 2.8–3 cm wide, with slightly recurved densely white ciliated margin, densely hairy outside, light green with broad brown stripes joined in basal half into broad brown field. Synsepal concave, elliptic, obtuse, 2.2–2.5 cm long, 1.4–1.6 cm wide, densely white hairy outside, light green, brown at the base. Petals reflexed, nearly straight, narrowly obovate, obtuse or very shortly apiculate at apex, 5–5.5 cm long, 2.2–2.4 cm wide, white ciliate along whitish margin, purple-violet, greenish toward the base. Lip 4–4.5 cm long, 2–2.4 cm wide, dull pinkish-brown, with more deep colored veins, light dull greenish at the apex of the pouch and on side lobes. Staminode broadly obovate, 7–9 mm long, 9–11 mm wide, distinctly apiculate at the apex, dull olive yellowish-green, with low ovate emerald-green umbo and small irregular green spots in center part. Pedicel and ovary 3–3.4 cm long, green, deep purple-violet pubescent (Figs. 8 A–B, page 460; 9, page 461). ETYMOLOGY: This taxon is named after Phillip Cribb, an English botanist and specialist in the orchid family.

Fig. 6. In remote areas inaccessible to commercial collectors, Paphiopedilum villosum is not rare and occurs as a lithophytic
herb forming large colonies on shady mossy vertical bluffs and on large boulders along rocky ridge edges and on mountain tops.

Fig. 7. Scheme of supposed natural hybridization of Paphiopedilum appletonianum and P. villosum in Vietnam (photographs of both parental species were made in their sympatric populations studied in the territory of southern Vietnam).

Flowering: October–December.

Ecology: Terrestrial and lithophytic clustering rosulate herb. Montane, wet, mossy, closed, evergreen, broad-leaved and coniferous primary forests on shale, sandstone and granite at elevations between 1,400–2,000 m a.s.l (4,600–6,500 feet).

Distribution: Vienam (Lam Dong Prov.).

Note: Paphiopedilum × cribbii, undoubtedly a natural hybrid of P. appletonianum (Gower) Rolfe and P. villosum (Lindl.) Stein, was found in the area were both species are common and form large sympatric populations, often in the same habitats. The type plant is morphologically intermediate in all features observed between its putative parental species, including the shape and coloration of the sepals, petals, lip and staminode, the hairiness of the stalk, floral bract and ovary as well as the tessellation and form of its leaves. The tall erect inflorescence stalk, typical for P. appletonianum, appears as a dominant feature of the hybrid plant. In other morphological features, the influence of parental species is more or less equal. Paphiopedilum × affine De Willd., a taxon of questionable hybrid origin, sometimes speculatively regarded as a possible hybrid of P. appletonianum and P. villosum (Cribb in Averyanov et al., 2003), has a maroonspotted dorsal sepal and undoubtedly cannot be a hybrid of these species which have no distinct spots on the median sepal. The description of P. ×affine indicates that this plant may rather represent any derivate of P. gratrixianum (Masters) Rolfe or hybrid of this species and a species with mottled leaves such as P. appletonianum.

Litterature cited

Averyanov, Leonid, Phillip Cribb, Phan Ke Loc, Nguyen Tien Hiep. 2003. Slipper Orchids of Vietnam. With an Introduction to the Flora of Vietnam. Royal Botanic Gardens, Kew. Compass Press Limited.

Fig. 8. Paphiopedilum ×cribbii (appletonianum × villosum). A. Flower. B. Flowering plant.

Fig. 9. Paphiopedilum ×cribbii (appletonianum × villosum). A. Flowering plant. B. Flattened sepal, synsepal and petals. C. Lip, frontal view. D. Lip, sagittal section. E. staminode. F. Floral bract and ovary. All drawn from the type by L.V. Averyanov.

Field and laboratory studies, the results of which are presented in this paper, were made under the auspices of the 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” USA. National Geographic Society, 2004; and investigation program of Vietnamese Botanical Conservation Program supported from Henry Luce Foundation (USA). We thank Dr. Alexander Sennikov for his kind correction of our use of the Latin language in the Latin diagnosis.

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