Asarum ampulliflorum, Lu & Wang, 2014

Lu, Chang-Tse & Wang, Jenn-Che, 2014, Asarum ampulliflorum (Aristolochiaceae), a new species from Taiwan, Phytotaxa 184 (1), pp. 46-52 : 47

Asarum ampulliflorum C.-T. Lu & J.-C. Wang, sp. nov. ( Fig. 1 )

TYPE:― TAIWAN. Ilan County: Taipingshan , Houshan Park, elev. ca. 2,000 m , C.- T. Lu 567 (holotype TNU!; isotype TNU!) .

Asarum ampulliflorum is similar to A. asaroides in appearance, but can be differentiated by leaf length equal to width (vs. longer or shorter than width), perianth tube smaller (8.7–11.7 mm × 13.8–18.1 mm vs. 20.0–25.0 mm × 25.0–30.0 mm) and more compressed (ratio of the perianth tube length to the diameter at the widest points of perianth tube 0.62−0.66 vs. 0.80−0.83), and limb lobe nearly as long as perianth tube (vs. lobe shorter than perianth tube).

Perennial herbs. Adventitious roots few, glabrous, as thick as rhizome. Rhizome glabrous, repent, suberect; annual vegetative branch with 2–3 cataphylls at base, cataphylls membranous, hyaline, sessile, oblong, glabrous on both surfaces, margin hairy, obtuse at apex. Leaves petiolate; petiole 6–12 cm, pilose adaxially, grooved, dark brown or purple; lamina cordate to triangular-ovate, acute at apex, cordate, 5.5–8.5 cm × 5.0–8.0 cm, lobes 1.5–2.0 cm × 2.0– 2.5 cm wide; adaxial surface usually dark green, pubescent, with white maculae, abaxial surface purple or pale green; adaxial surface and margin of young leaves usually short hairy. Flowering branch with 2 cataphylls at base, cataphylls ovate, glabrous on both surfaces, margin hairy; flower solitary, emerging the axil of a young leaf, dark purple, decumbent on ground; pedicel glabrous, 5–10 mm long; perianth tube pyriform, 8.7–11.7 mm long, upper part inflated, ca. 13.8–18.1 mm in diam. at the widest points, 8.0– 10.1 mm in diam. at the base of tube, outside glabrous, white, inside reticulate, ridged, purple, longitudinal ridges 24; limb 3-lobed; perianth tube entrance 3–8 mm in diam.; orifice rim well-developed, 2.4–4.0 mm wide; perianth-lobe spreading obliquely, slightly undulated, triangulate to ovate, 7.1–13.7 mm × 15–17 mm, pubescent adaxially, glabrous abaxially; tubercle white, present between orifice rim and perianth-lobes; stamens 12 in 2 whorls, 2–3 mm long, filaments very short, anthers extrorse and lateral, ca. 1.2–2.0 mm long, apex of connectives rounded or triangular; with 3 rudimentary petals; ovary superior, 6-locular,fused at base; styles 6, free; stylar protuberance bi-lobed, with a broadened wing on each side, round at apex, 1.0– 2.2 mm long; stigma lacrymiform, lateral; ovules 8 in each locule; capsule fleshy, perianth tube present; seeds ellipsoid, brown, with fleshy elaiosome on ventral surface.

Phenolgy: ―Flowering from December to March.

Habitat and distribution: ― Asarum ampulliflorum is endemic to Taiwan, occurring in mixed broad-leaved and conifer forest in the northeast part of Taiwan, at elevations of 900–2100 m on the Hsueshan Mountain Ridge and Central Mountain Ridge ( Fig. 2 ). Its habitat is humid through the year and plants often grow there among bryophytes.

Etymology: ―The specific epithet “ampulliflorum” was given based on the inflated, pyriform perianth tube.

Somatic chromosome number: ―We determined the somatic chromosome number of A. ampulliflorum as 2 n = 24, equaling all the other species of Asarum sect. Heterotropa in Taiwan ( Sugawara & Ogisu 1992, Huang et al. 1995, Lu & Wang 2009, Lu et al. 2009, Lu et al. 2010, Lu & Wang 2013) and most species in Japan ( Ono 1960, Yuasa & Maekawa 1976).

Morphological comparison: ―Morphologically, the pyriform perianth tube and the complex reticulation pattern on the inner surface of the perianth tube show that A. ampulliflorum is related to A. asaroides (Morr. et Decne.) F. Maekawa , A. macranthum Hooker f., and A. satsumense F. Maekawa from Japan or Taiwan. However, A. ampulliflorum can be distinguished from the latter three species by the leaf shape and size, ratio of the perianth tube length to the diameter of the widest points of perianth tube ( Fig. 3 ), ratio of the perianth-tube length to limb-lobe length ( Fig. 3 ), color of the inner surface of the perianth tube, stigma, and stylar protuberance shape ( Fig. 4 ). Asarum ampulliflorum is most similar to A. asaroides , however, it differs from the latter by having cordate to triangular-ovate (vs. widely ovate to ovate triangular) leaves, small flowers (the widest diam. of perianth tube <20 mm vs.> 20 mm) and long limb lobes (ratio of tube length to limb-lobe length 0.86–1.21 vs. 1.67–2.0). Asarum ampulliflorum also resembles A. macranthum and A. satsumense , but can be differentiated from the latter two by its lacrymiform (vs. unciform) stigma and 2-lobed stylar protuberance with a broadened wing on each side (vs. 2-lobed, with a horn-like protuberance on each side). The detailed differences of these four species are shown in Table 1. In addition, we provide a key to these four closely related species to aid in identification.

Figures

FIGURE 1. Asarum ampulliflorum C.–T. Lu & J.–C. Wang (from holotype). A. Habit. B. Apical view of flower. C. Longitudinally dissected flower. D. Outer whorl stamens. E. Inner whorl stamens. F. Style and stigma. G. Dissected ovary. (drawn by C.–T. Lu)

FIGURE 2. Geographical distribution of Asarum ampulliflorum C.–T. Lu & J.–C. Wang, A. asaroides Morr. et Decne., A. macranthum Hooker f., and A. satsumense F. Maekawa.

FIGURE 3. A histogram showing differences in the ratio of the perianth tube length to the diameter at the widest points of perianth tube and the ratio of the perianth tube length to limb-lobe length among Asarum ampulliflorum (am), A. asaroides (as), A. macranthum (ma), and A. satsumense (sa). The lines in the plot indicated the range of each character from each species.

FIGURE 4. Comparison of stigma and style morphology of Asarum ampulliflorum (A), A. asaroides (B), A. macranthum (C), and A. satsumense (D).