Typhonium, Schott

TYPHONIUM Schott View in CoL

The genus Typhonium (Araceae-Aroideae-Areae) currently comprises c. 70 described species.

Prior to Cusimano et al. (2010) Typhonium numbers were higher because of the inclusion of the genera Sauromatum Schott and Lazarum A.Hay , which are since recognized as separate from Typhonium .

Typhonium is widely distributed in tropical and subtropical Asia; Indochina is one of the most important centers of diversity: 34 species are recorded for Thailand, 21 for Vietnam, while the aroid floras of Laos and Cambodia remain poorly known.

The genus comprises small seasonal geophytic herbs; under- ground part a (sub)globose tuber or a very short rhizome; leaves one or several; lamina simple, cordate, hastate, elliptic or lan- ceolate, or decompound, with few to many leaflets, variable in shape; inflorescence usually appearing after leaf development; peduncle short or long; spathe ovate, elliptic-ovate, narrow or broadly triangular or lanceolate, base and limb separated by a more or less conspicuous constriction just below the staminate zone of the spadix, limb often with a pale or deep purple inside, more rarely whitish or pinkish; spadix with a small basal pistillate zone, then a sterile zone with a staminode-bearing lower part and a smooth upper part (rarely with vestigial staminodes) and then a staminate zone topped by a sterile appendix; appendix short or very long, erect, oblique or pendulous, elongate, nar- rowly conical or long, thin tail-like.

The genus was revised by Sriboonma et al. (1994; with 40 species treated), but quite a number of species have been discovered since that publication, see Hetterscheid et al. 2001, Hetterscheid & Nguyen 2001, Hetterscheid & Galloway 2006, Nguyen 2008, Nguyen & Croat 2010, Galloway 2012, Hetterscheid & Sookchaloem 2012, Hetterscheid 2013, Van et al. 2017, 2021, Naive et al. 2020, Naive & Hein 2021, Hein & Naive 2021, Nguyen et al. 2022.

Typhonium View in CoL is considered the third largest genus of Araceae View in CoL in Vietnam (after Amorphophallus View in CoL with at least 37 species and Arisaema View in CoL with more than 20 species) but its knowledge is very far from satisfactory. The number of recorded species increased from 13 in 2017 ( Nguyen 2017) to 19 in 2021 ( Van et al. 2021) and to 20 in 2022 ( Nguyen et al. 2022); there are very scanty data on the variation between and within Typhonium species, geographic distributions and ecology. With the description of T. praelongum View in CoL we conclude that the number of Arisaema View in CoL and Typhonium species recorded for Vietnam is about equal which may change any time due to new discoveries and progress in taxonomic research.