Rohdea grandiflora H.Z.Feng & Q.X.Han, 2022

Feng, Hui Zhe, Yu, Miao, Fang, Hong Lin & Han, Qing Xiang, 2022, Rohdea grandiflora (Asparagaceae), a new species from southern Gansu, China, Phytotaxa 552 (3), pp. 208-212 : 208-211

Rohdea grandiflora H.Z.Feng & Q.X.Han , sp. nov. ( Figs. 1 , 2 )

Most similar to R. pachynema in sharing a long slender subterranean stolon, but differs mainly by the longer inner bracts, larger flowers, and columnar filaments adnate to middle or base of perianth lobes and not connate to adjacent ones.

Type:— CHINA. Gansu Province: Longnan , Kang County, collected in nature on 8 August 2021 by Y. L. Cui; herbarium specimen prepared from the plant cultivated in garden in Zaozhuang University on 7 April 2022, Feng 2022–0317 (holotype, CSH!) .

Description:—Plant herbaceous, perennial, rhizomatous. Rhizome fleshy, cylindrical, (3)5–10(13) cm long, (1.5)3– 3(3.5) cm in diameter, externally greenish grey, internally white or cream, with many annular leaf scars, internodes (0.3)0.5–2(2.5) cm long, producing long slender subterranean stolons to 65 cm or longer, 2.5–4.5 mm in diameter. Roots cordlike, (2)2.5–3(4) mm in diameter, fleshy, velutinous. Stem ascending, nearly erect, cylindrical, (2)4.5–8(10.5) cm long, (1)2.5–3(4) cm in diameter, brown or light orange, bearing 8–13 leaves. Leaves basal, equitant, narrowly oblongelliptic, somewhat undulate, recurved, coriaceous, up to 60 cm long and 5 cm wide, dark green and somewhat lustrous adaxially, green and paler abaxially, smoot on both sides, margin entire; midrib adaxially impressed and abaxially raised; secondary veins numerous, parallel, closely spaced at intervals of (1.0)1.5–2.0(2.5) mm. Peduncle semiterete, 6.5–9.5 cm long, (0.4)0.5–0.6(0.7) cm in diameter, Inflorescence a spike of ca. 7–12 flowers, cylindrical, ca. 6.5 cm long, ca. 5.0 cm in diameter; rachis fleshy. Flower-subtending bracts and bracteoles white with green tint to pale green or yellowish green, subcoriaceous; margin entire, membranous, whitish. Flower-subtending bract lanceolate, (1.8)2–2.5(3.0) cm long, (2)2.4–3.5(4) mm wide at base; margin entire; distal bracts longer than proximal ones, mostly longer than flowers. Bracteole linear, 8–9.5(11) mm long, (0.5)1–1.5(2) mm wide at base. Flowers sessile, borne in shallow pits between ridges on rachis, facing almost horizontally except for some distal flowers facing slightly upward. Perigone (nearly) funnel-shaped, with tube and 6 lobes, (2.0)2.3–2.5(2.8) cm in diameter, fleshy, green, turning yellow at late anthesis; perigone tube broadly crateriform, (8.8)9.0–10.0(12.0) mm long, (21.0)22.0–24.5(25.0) mm in diameter; perianth segments often obliquely ascending, broadly ovate, (4.5)5–5.5(5.8) mm long, (4.3)4.8–5.2(5.5) mm wide at base, margin entire, apex subacute to obtuse and deflexed. Stamens 6, inserted at bases or middle parts of perigone lobes; filaments columniform, ca. 2.5 mm long, not dilated toward base; anthers dorsifixed, biloculate, introrse, orbicular-ovate, retuse proximally and distally, 0.8–0.9(1) mm long, 1–1.5 mm wide, facing downward. Pistil 1, tricarpellate, erect, 4.5–5.2(5.5) mm long; ovary superior, ovoid, (2.4)3.0– 3.2 mm long, 2.3–2.6(3.1) mm in diameter (broadest below middle), 3-locular, with scattered white minute dots; style conspicuous, 2.3–2.5(2.7) mm long, 0.7–0.8(1.3) mm in diameter; stigma positioned nearly at the same level with anthers, trisected, 0.2–0.4 mm long, 0.6–0.8 mm wide, erect, surface papillulate. Fruits not seen.

Etymology:—The specific epithet refers to the large flowers of the new species.

Distribution:—Currently known only from Kang County, Longxi City, Gansu Province, China.

Taxonomic relationships:—In Rohdea only two species, R. grandiflora and R. pachynema ( Wang & Tang 1949: 18) N. Tanaka (2010: 35) ( Fig. 2 B, C & D ), have a long slender stolon, suggesting that the two species are close in relationship. Rohdea grandiflora is easily distinguishable from R. pachynema mainly by the longer bracts, larger flowers (23–25 vs. 7–10 mm across), filaments inserted in the middle or basal portion (vs. subdistal portion) of the perianth lobe, not broadly dilated (vs. dilated) toward base, and not connate (vs. connate) to adjacent ones. Tanaka (2010) presumed that R. pachynema is a descendant from the ancestral lineage of R. fargesii ( Tanaka 2019) , in that the filaments of these two species inserted at base of perianth lobe, incurved, decurrent parts on tube usually dilated and united with adjacent ones, forming small protuberance at each junction. R. grandiflora , appears to be the sister species of R. pachynema , was also descended from the ancestral lineage of R. fargesii but the filaments adnate to middle or base of perianth lobes and not connate to adjacent ones. Based on Raunkiaer (1934) the species have stolon that belongs to Cryptophytes which adapted well to the alpine climate characterized by low temperature and short growing season. The distribution area of R. pachynema has a high altitude (e.g. 3700 m in G.H. Yang 3896, PE00593144) and R. grandiflora also distributed at the highest latitude, where a colder climate prevails than in the central or southern part of the generic range. Development of long slender stolon in the two species may also reflect the colder climate which beneficial to reproduction after abortion in cold environment in spring.

Additional specimens examined:— CHINA. Sichuan: Leibo , 2400 m, 12 August 1972 , Sichuan vegetation investigation group 0695 ( PE02085406 ). Luding, 2 May 1981 , 2200 m, G. H. Xu 25379 ( CDBI0166770 ). Mianning , 3500 m, 3 Luly 1978, Mianning Group 0279 ( SM722208182 ). Xichang, 2700 m, 2 April 1985 , Y. J. Li 595 ( CDBI0166766 ). Yuexi, 3700 m, 13 July 1959 , G. H. Yang 3896 ( PE00593144 ). Zhaojue, 2300 m, 6 May 1984 , Sichuan vegetation investigation group 32176 ( CDBI0166768 ) .

Figures

FIGURE 1. Rohdea grandiflora. A. Habit. B. Inflorescence. C. Leaf detached. D & G. Plant bearing a stolon. E. Leaf blade (a) and outer bract (b) and inner bract (c). F & I. Flower in lateral view. H. Half flower, frontal view. J. Ovary in transverse section. K. Pistil. L. Flowers from different plants.

FIGURE 2. A. Inflorescence of Rohdea grandiflora. B. Inflorescence of R. pachynema (some perianth lobes removed). C & D. Flower of R. pachynema