Pothos L. is a genus of c. 70 species of
subtropical and tropical, predominantly forest root-climbing lianes
distributed from Madagascar to Western Oceania (east to Vanuatu)
and China (north to Hubei) to Australia (Queensland, New South Wales).
The greatest diversity is met with in Indomalesia where the largest
concentration of species and widest diversity is to be found in
Borneo (see e.g., Hay et al. 1995).
Pothos is placed in tribe Potheae (sensu Mayo et al.1997),
a palaeotropical assemblage of three very similar, possibly inseparable,
genera. Besides Pothos, the other genera, both monospecific,
are Pothoidium Schott and Pedicellarum M. Hotta. For discussion
of generic delimitation in Potheae see Boyce & Hay (1998).
Linnaeus (1753, 1763) treated Pothos as a genus of climbing
aroids with bisexual flowers. Subsequently many climbing aroids
were included to form a heterogeneous assemblage. Early in the 19th
century Schott recognized that Pothos was, as then defined,
unnatural and in a series of papers (Schott 1832, 1856
1857, 1860) redefined bisexual-flowered aroid genera. The
current circumscription of Pothos is essentially that of
Schott (1832, 1856 1857, 1860). Schott (1856 1857)
established two subgenera, Pothos (as EuPothos) and
AlloPothos. Engler (1905) further subdivided Schotts
subgenera (referring to them as sections) into seven series. While
accepting Schotts subgenera, no attempt is made here to follow
Since the last revision of Pothos (Engler 1905) several geographical
reviews have been published (e.g., Li 1979; Sivadasan 1982; Nicolson
1988; Hay 1995). To date no critical account of the genus has been
prepared for Peninsular Malaysia (but see Hooker 1893, Ridley 1925),
Borneo (but see Miquel 1856; Ridley 1905 and Merrill 1921), the
Philippines (but see Merrill 1923) nor Thailand and Indochina (but
see Gagnepain 1942, Hu 1968 and Boyce & Nguyen 1995).
This review is based primarily on existing Thai, Chinese and Vietnamese
collections and extensive fieldwork in Thailand, Vietnam and, to
a lesser degree, China. The political situation in other parts of
the region have necessarily limited greater study. By way of example
the total number of Pothos collections located for Cambodia
is four (representing two or three species), for Lao P.D.R., 14
(four species) and for Myanmar, 35 (two species) from a total of
645 collections seen.
As with previous papers (Hay 1995, Boyce & Hay 1998) no attempt
to group species other than at the level of subgenus (and that primarily
for convenience, to aid identification) has been made. It is still
far from clear whether Pothos as currently defined is a monophyletic
genus (see Boyce & Hay 1998 for discussion) and attempts to
group species formally are premature pending current studies.