Thismia, Griffith, 1845

Nuraliev, Maxim S., Yudina, Sophia V., Truong, Ba Vuong, Do, Thi Xuyen, Luu, Hong Truong, Kuznetsov, Andrey N. & Kuznetsova, Svetlana P., 2020, A revision of the family Thismiaceae (Dioscoreales) in Cambodia, Laos and Vietnam, Phytotaxa 441 (3), pp. 229-250 : 242

Thismia . okhaensis Luu, Tich, G.Tran & Đinh in Luu et al. (2014: 190, Fig. 1 , 2 )

Literature:— Kumar et al. (2017: 232)

TYPE: — VIETNAM. Khanh Hoa Province: Khanh Son District, Hon Ba Nature Reserve (former Khanh Son Protection Forest), O Kha Valley, approximate coordinates N 12°02’57’’ E 108°59’10’’, elevation ca. 800 m, 12 July 2013, Nguyen Thien Tich, Tran Gioi, Dinh Quang Diep, Luu Hong Truong, Nguyen Thanh Trung KH 638 B (holotype: SGN!).

Description

Plant generally glabrous. Roots vermiform. Leaves scattered, 3 mm long. Flower terminal and solitary (but with a small lateral bud which probably develops into a lateral flower), actinomorphic, ca. 30 mm long, surrounded by an involucre of 3 bracts 7 mm long. Hypanthium 9–10 mm long, translucent black, bluish brown at base, externally with longitudinal stripes.Annulus vertical (erect), white. Outer tepals ca. 4 long, ca. 6 mm wide, translucent white, reflexed, furrowed, mucronate, margin entire. Inner tepals white, apically fused to form a thick convex-topped mitre and leaving 3 arch-shaped lateral apertures; apertures completely hidden under the mitre, ca. 3 mm long and 7 mm wide. Outer surface of mitre digitately furrowed at top; inner surface with glandular hairs. Stamens with long supraconnectives, fused laterally along their entire length except for the filaments and the apices to form a stamen tube. Each stamen with median longitudinal furrow at the inner (abaxial) side. Connectives and supraconnectives translucent light brown. Supraconnectives bearing skirt-like appendages at the outer (adaxial) side slightly below thecae; appendages quadrangular, translucent yellowish brown, with two lateral teeth and glandular hairs. Thecae adaxial (facing the hypanthium), separate, 2 mm long. Interstaminal glands present. Ovary 2.5 mm long, outside translucent white and bluish brown at top. Placentas column-like. Stylar column ca. 0.8 mm long; styles ca. 1.5 mm long, bearing papillose stigmas, translucent bluish brown.

Etymology: —The specific epithet “ okhaensis ” refers to the O Kha Valley, the type location of this species.

Phenology: —Flowering in July.

Distribution: —Endemic to Vietnam, Hon Ba Nature Reserve. Only known from the type collection.

Notes:— Thismia okhaensis is morphologically very similar to T. puberula ; see note under the latter species.

Figures

FIGURE 1. Distribution map of the species of Thismia in Cambodia, Laos and Vietnam.

FIGURE 2. Thismia annamensis. A–D. Nuraliev 1562; E–G. Nuraliev 999. H. Nguyen Quoc Dat et al. Pl_Q.NG 0025; all photos by M. Nuraliev except for H by Nguyen Quoc Dat. A. Habit. B, E. Flower, apical view. C. Annulus and stamens, lateral view. D. Flower, longitudinal section. F. Flower with a longitudinal half of hypanthium removed, oblique-bottom view. G. Longitudinal section of distal part of flower showing stamen structure. H. Styles, apical view.