Thismia sect. Labiothismia Smith (1927: 222)

Nuraliev, Maxim S. & Sennikov, Alexander N., 2024, A checklist of Thismia section Labiothismia (Thismiaceae), reinstated to include Asian species earlier placed in the neotropical T. sect. Glaziocharis, Phytotaxa 662 (1), pp. 93-101 : 96

Thismia sect. Labiothismia Smith (1927: 222)

Type species:— Thismia labiata Smith (1927: 220) .

Synonym:— Thismia sect. Glaziocharis Kumar et al. (2017: 233) , nom. illeg., non (Taub. ex Warm.) Hatusima (1976). Type species:— Thismia abei (Akasawa) Hatusima (1976: 7) .

Description:—Herbs up to 6(–10) cm tall. Underground part represented by creeping vermiform roots. Flowers terminal and solitary (sometimes in monochasium in T. thaithongiana ), surrounded by involucre of usually 3 bracts. Flowers actinomorphic or zygomorphic (zygomorphy due to bent hypanthium, or bilabiate-looking annulus and perianth, or manner of tepal fusion), variously coloured. Hypanthium inner surface without transverse bars, usually smooth. Annulus of various shape, more or less ring-like. Outer tepals unappendaged or with appendages ranging from short protuberance-like to long and filiform. Inner tepals with appendages ranging from short protuberance-like to long and filiform (unappendaged in T. americana ). Inner tepals postgenitally fused into a mitre (reports of tepals overlapping to form a loose dome need verification: Nuraliev et al. (2024)). Mitre often with imbricate (or contort) tepal aestivation. Stamens laminar, with long supraconnectives, fused postgenitally into a stamen tube (reports of free stamens need verification: Nuraliev et al. (2024)). Supraconnective usually distally bent outwards, without skirt-like or wing-like appendage, with entire apex (without teeth). Interstaminal glands absent. Thecae sometimes surrounded by rows of glandular hairs. Placentas parietal, usually becoming column-like by detachment from ovary wall; styles terminating stylar column, united into a pyramidal structure or free. At fruit maturation, hypanthium abscises circumscissily. Fruit cup-shaped (a pyxidium), dehiscing apically by withering; pedicel sometimes elongating greatly during fruit maturation.

Taxonomic notes:— Thismia sect. Labiothismia is uniform in a set of morphological traits that also makes the section distinct from the rest of the genus. These traits are: underground organs represented by vermiform roots; absence of transverse bars inside the hypanthium; inner tepals forming a mitre or a loose dome (possibly, exclusively a mitre: see discussion by Nuraliev et al. 2024); presence of appendages of the inner tepals that are usually longer than 1 mm (but the inner tepals are unappendaged in T. americana Pfeiffer (1914: 123)) ; absence of a wing-like appendage of supraconnective; absence of interstaminal glands.

Distribution: — India (Western Ghats), Japan, China (Yunnan), Taiwan, Thailand, Laos, Vietnam, Peninsular Malaysia, Indonesia (Sumatra), USA (Illinois).

All of the 14 species of the section, except for T. abei , are known to be narrow endemics restricted to the type localities or their close vicinities ( Fig. 1 ).

Figures

FIGURE 1. Distribution map of the Asian species of Thismia sect. Labiothismia. The only non-Asian species of the section, T. americana, is endemic to Chicago (USA: Illinois).