Eupatorieae

Grossi, Mariana A., Katinas, Liliana & Nakajima, Jimi N., 2013, Criscianthus, a new genus of Eupatorieae (Asteraceae) with a key to members of the tribe in Africa, Phytotaxa 141 (1), pp. 25-39 : 31

The Eupatorieae in Africa

The Eupatorieae in Africa are represented by 10 genera and about 27 species, including the newly described monotypic genus ( Table 1). Regarding other regions of the world, the tribe Eupatorieae has few representatives in this continent. The African Eupatorieae are Adenostemma Forster & Forster (1776: 89) , Ageratina Spach (1841: 286) , Ageratum , Campuloclinium Candolle (1836: 136) , Chromolaena Candolle (1836: 133) , Criscianthus M.A.Grossi & J.N.Nakaj. , Eupatorium , Fleischmannia Schultz Bipontinus (1850: 417) , Mikania Schmidt (1795: 272) , and Stomatanthes . Overall, these genera belong to eight different subtribes of Eupatorieae , with five genera represented by only one species. The subtribe Eupatoriinae contains the major number of genera: Criscianthus , Eupatorium , and Stomatanthes , two of them native to Africa. Considering all the genera, there are 16 native species on the continent and 11 are alien. Species of Ageratina , Ageratum , Campuloclinium , and Chromolaena are alien invaders and weeds in the region ( Table 1). One of these, Chromolaena odorata ( Linnaeus 1759: 1205) R.M. King & Robinson (1970c: 204) , has become a very aggressive, invasive weed, first recorded as naturalized in South Africa in the late 1940s, and then spread all over the continent ( Zachariades & Goodall 2002, Paterson & Zachariades 2013). On the other hand, Mikania , Adenostemma and Stomatanthes have species considered of importance in host-specificity trials of potential biological control agents ( Retief 2002). In this sense Criscianthus zambiensis could be considered as another candidate to explore the control of the threat that Chromolaena odorata represents not only in Africa but internationally, to agriculture and biodiversity.

It is important to remark that apparently there is nomenclatural confusion and misidentifications in some African Eupatorieae . For example, in the past authors tended to recognize a single, variable, pantropical species Adenostemma viscosum Forster & Forster (1775: 90) , but then a broad view of the species gradually occurred with the recognition of more species although with some morphologic overlapping. The names Adenostemma lavenia ( Linnaeus 1753: 902) Kuntze (1891: 304) , A. lavenia var. lavenia , and A. viscosum have been variously applied to this widespread taxon in some floras of Asia and the Pacific regions. Here we apply the name Adenostemma viscosum according to King & Robinson (1987) who restricted the distribution of A. lavenia to Sri Lanka. A more extended discussion on this topic is developed by Orchard (2011). On the other hand, Mikania scandens ( Linnaeus 1753: 836) Willdenow (1803: 1743) and M. cordata (Burmann 1768: 176) Robinson (1934: 65) , of the " Mikania scandens " complex, have been reported for Africa ( Table 1), but the presence of both species on the continent is dubious ( Holmes 1982; Walter Holmes, pers. comm.). Mikania scandens is generally limited to the United States and sparsely found in the Bahama Islands and northeastern Mexico. It seems that the reports of the species throughout much of the Americas are better treated under other names, and those reports of M. scandens in the Old World are misidentifications. According to Holmes (pers. comm.) at one time the name Mikania scandens was used to refer to all of the Mikania species of Asia and the Pacific region, Africa, and many South and Central American species. Regarding Mikania cordata , the species might be limited to southeastern Asia ( Burma to Hainan), Indonesia, the Philippines, and eastward to New Guinea and the Solomon Islands. Despite the probable absence of both species in Africa but due to the complexity of this group of species, we decided to include Mikania cordata and M. scandens in the key below to facilitate future specimen’s identification.