Rohdea gymnogyna H. Z. Feng, 2024

Feng, Hui Zhe, Xu, Ting, Bi, Ming Hui, Zhao, Yan Ying, Chang, Ce & Wang, You Jun, 2024, Rohdea gymnogyna (Asparagaceae), a new species from southern Gansu, China, Phytotaxa 634 (1), pp. 85-90 : 86-89

Rohdea gymnogyna H. Z. Feng , sp. nov. ( Figs. 1 A, B, D–L .)

Type:— CHINA. Gansu (flffi): Longnan ( Ḕ 南), Wenxian ( Ž 县), Liujiaping (刘※坪), alt. 1804 m, H. Z. Feng & Y. J. Wang WX-202108013, dried herbarium specimen prepared by H. Z. Feng 2023–109 (holotype, SYS!), on 7 April 2023 from a plant cultivated at Biological Garden of Zaozhuang university, Zaozhuang, Shandong, China. Sichuan, Chengdu, Chongzhou, Jiguan Mountain, alt. 1884 m, on 3 May 2022, H. Z. Feng 2022–571 (paratype, SYS!).

Diagnosis:—This species is most similar to R. rotiformis in in sharing character of at orifice of tube developing annulus, but differs mainly by the entire leaf blade; perianth lobes lanceolate, ca. 5.0 mm long, ca. 2.5 mm broad in base and strongly curved into a "W" shape in longitudinal section, tube bowl-shaped, shallow, ca. 2 mm deep, the perianth tube is tube very short and bowl-shaped, the ovary extends beyond the perianth tube; the stigma protruding outside perianth tube and one-third of ovary not covered by annular appendages.

Description:—Hemicryptophyte herb, ca. 30 cm high. Rhizome cylindrical, prostrate, ascending distally (erect or suberect in young plants), to 1.5–2 cm in diameter, unbranching, thick and fleshy, apical part crowded with several distichous leaves. Cataphylls (0)2–3(4) at base of annual tuft of foliage leaves, equitant, narrowly triangular, acute, 3.5–6 cm long, 1–1.5 cm wide, at base to 2–3.5 cm wide. Leaves (3)4–6(7) sub-distichous, equitant, oblanceolate to broadly oblanceolate, (10)20–35(40) cm long, (1)1.5–2(3) cm wide, gradually tapering to thick, petiole-like, canaliculate basal part, acute to shortly attenuate at apex, arcuate to pendulous, with distinct midvein, fleshy, leathery, uniformly green. Peduncle axillary in apical part of rhizomatous stem, erect, straight or slightly flexuose, rigid, subterete, irregularly angled or lunate in cross section, 3–4(5) cm long, 0.5–1 cm in diam, with 2–3 bracts, triangular, ca. 3.5 mm long and ca. 4 mm wide in the base. Inflorescence a terminal, spadix-like dense spike with many flowers, simple, (2.5)3–5(6) cm long, 1–1.5 cm in diam., apical part cristate with sterile bracts; rachis fleshy, longitudinally angled, with shallow floral pits. Floral bracts one per flower, narrowly triangular, lanceolate- or ovate-triangular, proximally slightly concave, margins entire, apex acute or shortly acuminate; bracts located below flower, ca. 5.0 mm long, ca. 3.5 mm wide, same height as flowers. Flowers sessile on shallow pits of rachis, open acropetally, fragrance, (7)8–10(12) mm across. Perianth starburst, nearly actinomorphic, distally 6-cleft, green, orange when old, somewhat glaucous. There is an annular ledge appendage on the top of the perianth tube, which protrudes outward, resembling a crater, the annular ledge ca. 4 mm in diameter, the ledge ca. 1 mm wide, inner margin entire, frontal surface flat, smooth, greenish; perianth lobe, lanceolate, ca. 4.5 mm long, 2.5 mm wide and strongly curved into a "W" shape in longitudinal section. Stamens 6, arising from top of perianth tube, concealed within the annular ledge and only the top of the anther is exposed, used for spreading pollen, filaments extremely short, ca. 0.5 mm. Pistil 1, proximally light green; ovary superior, globular, peach-shaped, ca. 3.5 mm in diameter, glossy, trilocular and the top third of the ovary exceeds the top of the perianth tube and the annular ledge; style to 1 mm; stigma, trisected. Fruit no see.

Etymology:—The specific epithet refers to the partially exposed ovary.

Habitat and phenology:—Primary and secondary broad-leaved evergreen-deciduous mixed forests at elevation 1700–2000 m a.s.l. Shade plants herb growing beside moist ditches. Flowers in cultivation in April–May.

Distribution:— China (Gansu province, Longnan city; Sichuan province, Chengdu). Local endemic to China.

Note:—The ovary of angiosperms is the most important structure of the flower and is the structure that breeds seeds. Under normal circumstances, ovary had been well protected and located at the innermost part of the flower. Some species of Rohdea have evolved complex structures (annular ledge) to protect the ovary, e.g. R. harderi N. Tanaka, D.P. Hannon & Averyanov in Tanaka et al. (2018: 2), R. verruculosa (Q.H. Chen 1987: 69) N. Tanaka (2003: 332) , R. lichuanensis (Y.K. Yang, J.K. Wu & D.T. Peng in Wang et al. 1991: 40) Yamashita & M.N. Tamura (2004: 369), R. medogensis , R. rotiformis & R. urotepala . Rohdea eucomoides ( Baker 1875: 581) N. Tanaka (2003: 332) and R. delavayi have long perianth tube that hides the ovary at the base, creating a safe environment. However, except for R. gymnogyna , there is no species in Rohdea with the ovary exposed on the perianth tube.

Although several plant species in Rohdea have annular ledge in the top of perianth tube, the new species is more closely related to, R. rotiformis ( Fig 2 ), R. lichuanensis ( Fig. 3 ) and R. urotepala ( Fig. 1 C, M right, N right, O). In these four species the stamens are sessile and situated under the annular ledge appendage while in R. harderi , R. verruculosa and R. medogensis the stamens are situated outside the annular appendage and filaments are obvious. R. lichuanensis is the most distinctive in these species, with its slender leaves 24–35 cm long, 0.4–1.2 cm broad, the edges of perianth lobes and annular ledge fringed, upper surface of the annular ledge covered with papillary projections and tube densely with whitish lamellate internally and at orifice. Rohdea rotiformis is most similar to R. urotepala in sharing character of at orifice of tube developing annulus, but differs mainly by the annular appendage upper surface smooth.

The new species is morphologically close to R. rotiformis , with their annular appendages upper surface smooth, but differs by in the former the perianth lobes lanceolate and strongly curved into a "W" shape in longitudinal section, the perianth tube is very short and bowl-shaped, the ovary extends beyond the perianth tube.

Figures

FIGURE 1. Rohdea gymnogyna: A. Habit; B. Inflorescence; D. Young flower in vertical view; E. Old flower in longitudinal section; F. Young flower inlateral view, three perianthlobes had been removed; G.Old flowers in lateral view;H.Young flower in longitudinal section; I. Young flower in longitudinal section and pistil had been removed; J. Old flowers in vertical view; K. Young flower in vertical view and tepals had been removed; L. Young flower in longitudinal section and tepals had been removed. C. Rohdea urotepala, inflorescence. M. Rohdea gymnogyna, left; R. urotepala, right. N. Rohdea gymnogyna, left; R. urotepala, right. O. R. urotepala, flower in longitudinal section.

FIGURE 2. Rohdea rotiformis: A. Habit of the plant from E’meishan, Sichuan, cultivated plants. B. Habit of the plant from Jinfoshan, Chongqing; C, D, E, L. Inflorescences; F, G, J. Flowers in vertical view; H. Flower, part of the perianth tube has been removed; I. Fower in longitudinal section; K. Flower in lateral view.

FIGURE 3. Rohdea lichuanensis: A, B. Habit; C, D. Inflorescences; E. Flower in vertical view. F. Flower in longitudinal section; G. Flower in longitudinal section and pistil had been removed; H. Upside down flower in lateral view.