Eutrema bulbiferum Y. Xiao & D. K. Tian, 2015

Xiao, Yan, Li, Chun, Hsieh, Tung-Yu, Tian, Dai-Ke, Zhou, Jian-Jun, Zhang, Dai-Gui & Chen, Gong-Xi, 2015, Eutrema bulbiferum (Brassicaceae), a new species with bulbils from Hunan, China, Phytotaxa 219 (3), pp. 233-242 : 238-241

Eutrema bulbiferum Y. Xiao & D. K. Tian , sp. nov. ( Fig. 3 & 4 )

Type: — CHINA. Hunan: Longshan, Oolong Mountain National Geopark, 29°10′32′′N, 109°28′23′′E, 847 m, 15 April 2013, LS-1634 (holotype: CSH, 0072379!; isotypes: JIU, MO, TAI, A, HAST) .

Eutrema bulbiferum is most similar to E. tenue and E. yunnanense in general morphology, but it differs from them in the rosulate fleshy bulbils in the leaf axil or near the stem base, fewer (1–4) ovules per ovary, and bended silique apex with a long beak up to 0.25 mm. A detailed morphological comparison among E. bulbiferum and the related species is shown in Table 3.

Perennial herb, 50–90 cm tall, glabrous or sparsely pilose on upper plant parts, rhizomes not fleshy. Stems decumbent with rosulate fleshy bulbils in middle and upper leaf axil or at base. Basal leaf: petiole 7–15 cm long, blade cordate to ovate, 3–6 × 3–6 cm, base cordate, margin slightly wavy or subentire, palmately veined, with distinct short apiculate callosities at vein ends, apex rounded or obtuse, trichomes absent or simple. Cauline leaf: alternate, petiole 1.5–4.0 cm long, blade broadly ovate to ovate-cordate, 2–4 × 2–4 cm, palmately veined, base and margin same as in basal leaf, apex acute. Racemes with bracteates only on lowermost flowers, elongated considerably in fruiting; fruit pedicels sometimes recurved and subappressed to stem, 1.0– 1.5 cm long. Sepals ovate, 1.5–2.5 × 1.0–2.0 mm. Petals white, oblong, 3.5–6.0 × 1.5–3.0 mm, apex obtuse to rounded; claw present, 0.5–1.1 mm long. Stamens 6, tetradynamous, outer 2 shorter than inner 4; filaments white, 2.0– 2.5 mm long, narrow conical; anthers ovate, 0.3–0.5 mm long, apex obtuse. Pistil 1.5–2.0 mm long, stigma capitate, unlobed or rarely 2-lobed. Silique dehiscent, short wand-like, slightly 4-angled, 5–8 × 2–3 mm, apex bended with a beak up to 2.5 mm long, ovules 1–4 per ovary, gynophore obvious or obsolete, septum complete. Seeds biseriate, oblong to ovate, plump wingless, 2.5–3.5 × 1.5–2.0 mm; seed coat obscurely reticulate to foveolate, slightly mucilaginous when wetted.

Additional specimens examined:— CHINA. Hunan: Longshan, Oolong Mountain National Geopark, 29°10′32′′N, 109°28′23′′E, 847 m, 21 April 2012, LS-094 ( CSH) ; Jishou , 28°21′31′′N, 109°33′49′′E, 410 m, 1 April 2013, Jishou- 20130401001 ( CSH) .

Distribution and habitat: —Despite extensive field surveys have been conducted before in central China by plant investigators, so far only two small populations of E. bulbiferum have been found in the very limited areas of Gulley Stone Forest, a part of Luota Stone Forest in the OMNG, and Dehang of Jishou, both in the northwestern part of Hunan province. In Gulley Stone Forest, the plants of this species were only observed under limestone wall nearby a small stream (area less than 3 m 2). In Dehang, this species only grows on a humid slope under a waterfall where the water drops make fog and often spill on plants (area less than 5 m 2). E. bulbiferum is probably calcicole and prefers a special shady and humid habitat consist of stream or waterfall, limestone in karst landform.

Phenology: —The flowering period was observed in the end of March to middle April. The fruits were found from April to May.After June, the aboveground part of plants gradually withered and died in the winter with dormant bulbils left. The bulbils are always present and will develop into plants in the next spring after breaking dormancy in winter.

Etymology: —The epithet is named for its fleshy rosulate bulbils in leaf axil or at stem base, which lack in other species of the same genus.

Conservation status: —Through observations from 2012 to 2014, based on the area of occupancy estimated to be less than 10 km 2 (CR: B2), species existing at only two separated locations (CR: B2a), quality of habitat continuing decline due to increasing tourism and heavy grazing (CR: B2b(iii)), E. bulbiferum should be considered Critically Endangered (CR: B2ab(iii)) according to the IUCN red list criteria ( IUCN 2001, 2014). Therefore, immediate conservation strategy should be taken.

Figures

FIGURE 3. A–K. Eutrema bulbiferum. A. Habit. B. Infructescence. C. Bubil in leaf axil. D. Inflorescence. E. Flower, top view. F.Petal. G. Bulbil near the base of stem. H. Stamen, adaxial side. I. Stamen, abaxial side. J. Pistil. K. Seed. (Drawn by Shuxin Piao from the holotype, LS-1634, CSH and other images).

FIGURE 4. A–K. Eutrema bulbiferum (LS-1634). A. Habitat. B. Whole plant. C. Bulbil near the base of stem. D. Bubil in leaf axil. E. Inflorescence, top view. F. Inflorescence, lateral view. G. Flower, top view. H. Infructescence. I. Opened silique and seeds. J. Seed. K. Stamen. (Photos by Yan Xiao & Daike Tian).