The dismantling of the overly broad concept of Vernonia Schreb. in the Old World was begun by Robinson (1999a). In that study, the primary point was fully established, that there are no true members of the genus Vernonia native to the Eastern Hemisphere. The genus Vernonia is almost entirely North American (Robinson 1999b). Still, acceptance of segregate genera would inevitably depend on establishment of a reasonably complete coverage of the tribe, defining properly phyletic segregates, and discovery of reasonable characteristics by which the segregates can be distinguished. The present effort concentrates on a related group that contains a number of mostly African, woody perennial species of the subtribe Erlangeinae having 5-angled achenes, blunt-tipped sweeping hairs on the styles, and tricolporate type A pollen (Keeley and Jones 1977, 1979), also known as sublophate pollen (Skvarla et al. 2005). Two elements of this group are here described as new genera, Hoffmannanthus and Jeffreycia.

Specimens examined were from the U.S. National Herbarium in Washington, DC. Microscopic structures were examined mostly using material mounted in Hoyer’s Solution (Anderson 1954). Preparation of pollen for scanning electron microscopy (SEM) consisted of acetolysis (Erdtman 1960) followed by the osmium-thiocarbohydrazide repeat procedure (Chissoe et al. 1995) and pulse sputter coating with a gold/palladium (60/40) target (Chissoe and Skvarla 1996). Examination was with a JEOL 880 (University of Oklahoma) SEM equipped with lanthanum hexaboride (LaB6) electron sources.

The genera Hoffmannanthus and Jeffreycia, described here as new, are evidently closely related, but of these only Hoffmannanthus has had its DNA sequenced (Keeley et al. 2007). The available DNA sequence results place Vernonia brachycalyx O. Hoffm., the type of Hoffmannanthus, in a subclade within the subtribe Erlangeinae (Keeley and Robinson (2009). According to the DNA sequence, that part of the subtribe contains Vernoniastrum H. Rob. (Robinson 1999a), and somewhat more distantly, Orbivestus H. Rob. (Robinson 1999a, 2009). Of these, Vernoniastrum differs by a more herbaceous habit, pointed sweeping hairs on the style branches, idioblasts of the achenes in transverse bands, and lophate, triporate pollen. Orbivestus has the same type of pollen as Hoffmannanthus, but the plant is more herbaceous, has heads in seriate or subscorpioid cymes, has nearly sessile T-shaped hairs on the stems, has strictly subimbricate and otherwise undifferentiated bracts in its involucres, has narrowly rhomboid raphids in the walls of the achenes, and has pointed tips on the sweeping hairs of the style branches. The sweeping hairs occur along the entire outer surface of the style branches. Sequence data is lacking for Jeffreycia, but on the basis of structural evidence, Jeffreycia is considered closer to Hoffmannanthus than Vernoniastrum or Orbivestus. As shown in the review by Herz (1996), Jeffreycia (as Vernonia zanzibarensis) and Hoffmannanthus (as Vernonia brachycalyx) also share an unusual type of glaucolide derivative that has otherwise been reported only from Bothriocline (as Bothriocline amplifolia), all three genera evidently members of the Erlangeinae in the strict sense.

The typical element of the subtribe Erlangeinae with the genera Erlangea Sch. Bip., Bothriocline Oliv. ex Benth., and Cyanthillium Blume consists of herbaceous plants with mostly lophate, triporate pollen, symmetrically T-shaped hairs, and sharply pointed sweeping hairs on the styles. In contrast, the two genera described herein are shrubbier or weakly arborescent with sublophate, tricolporate pollen having a continuous perforated tectum between the colpi, simple or asymmetrical non-T-shaped hairs, and blunt tips on the sweeping hairs.

The two new genera, Hoffmannanthus and Jeffreycia (Fig. 1), share one feature found in many Old World Vernonieae, namely the sweeping hairs which are restricted to the branches of the style and do not extend onto the upper shaft, a feature otherwise a defining characteristic of the tribe Vernonieae and the subfamily Cichorioideae. Jeffreycia may be the most extreme in this character, with the sweeping hairs usually failing to even reach the bases of the style branches.

These genera are treated here together to allow a more effective direct comparison. The most obvious differences between Hoffmannanthus and Jeffreycia are found in the hairs of the stems, the shape of the leaves, and in details of the corolla lobes. The hairs on the stems of Hoffmannanthus have a rather long, uniseriate multicellular stalk with an elongate, asymmetrically mounted horizontal cap cell at the tip, these hairs being what could be called L-shaped (Fig. 1D). In contrast, the hairs on the stems of Jeffreycia species are simple and unbranched. The leaves of Hoffmannanthus have long petioles below the distinct basal acumination of the blade, and have no auricles on the blades (Fig. 1A). The leaves of all Jeffreycia except the typical variant of the type species, Jeffreycia zanzibarensis (Less.) H. Rob., S. Keeley & Skvarla have short petioles and blades with auricles projecting laterally at the base (Fig. 1E, F, I–K). The corolla lobes in Hoffmannanthus are oblong-triangular, and usually recurved at maturity (Fig. 1B, C). Jeffreycia has corolla lobes that are strictly lanceolate, the sides not parallel in any part, but evenly convergent from the base to the tip (Fig. 1G, L). The lobes are erect though sometimes withered when dry, but never recurved. A less obvious difference is the tendency for the pappus bristles in Hoffmannanthus to be sordid or even rufous and broader in the distal half, while those of Jeffreycia tend to be white and narrowed above.

Jones (1981) placed the type species of Hoffmannanthus, Vernonia brachycalyx O. Hoffm., in his Vernonia subsect. Strobocalyx S.B. Jones, among species now placed in the mostly African Gymnanthemum Cass. and in the mostly Asiatic and Malaysian genus Strobocalyx (Blume ex DC.) Spach. Jeffrey (1988) placed the species in his group 2 subgroup B, in an aggregate 3, distinguished by its persistent involucral bracts, 5-angled achenes, and ovate to cordate, non-panduriform leaves. Vernonia brachycalyx was not treated in the first effort to resolve palaeotropical Vernonieae by Robinson (1999a). Relationships of the species of Hoffmannanthus are considered to be particularly close to Jeffreycia which was placed by Jeffrey (1988) in his group 2, subsection B, aggregate 2. The present study shows that the two genera share Type A sublophate pollen, 5-angled achenes with short raphids, and blunt sweeping hairs on the style branches. Like many of the Old World Vernonieae, the sweeping hairs in Hoffmannanthus are lacking on the upper shaft of the style, but unlike most Jeffreycia, are not lacking on the bases of the style branches. Both genera are most common in east Africa. It is concluded that the two genera described here as new are closely related to each other but distinct.

The second genus treated here, Jeffreycia, includes three of the species mistakenly placed in Gymnanthemum in the subtribe Gymnantheminae by Robinson (1999a), a genus from which the present group is now seen to be subtribally distinct. Among the most obvious differences are the presence in Gymnanthemum of a broad abaxial shield in the involucral bracts and the tendency for the inner involucral bracts to be deciduous in Gymnanthemum, instead of persistent as in Jeffreycia.

A genus that is possibly closely related to Jeffreycia is the recently described Uniyala H. Rob. & Skvarla of India and Sri Lanka (Robinson and Skvarla 2009) with which Jefferycia scarcely overlaps geographically, only through its one species in Sri Lanka. While superficially similar, Uniyala has a shrubbier habit with closely spirally inserted leaves, non-panduriform bases of the blades, elongate raphids and thinner walled cells in the achene wall, and short tubes on the corollas and corolla lobes that are not strictly triangular.

An apparent additional distinction between Uniyala and both Jeffreycia and Hoffmannanthus is the pollen. In all three genera, the pollen is approximately the same size, ca. 30 µm in diam. when dry, up to 50 µm in diam. in fluid, type A tricolporate or sublophate with a continuous perforated tectum between the colpi. However, in Uniyala the pollen has incipient muri more defined with fewer, larger incipient lacunae (Robinson and Skvarla 2009) than in the present group, where muri are obscure and the incipient lacunae are small and more numerous (Figs 2–5).

The generic segregates of Vernonia in tropical Africa are only partially resolved. A treatment of all but two species in Southern Africa is nearly complete, but it does not include any close relatives of the two genera described here. Nevertheless, the presently recognized tropical African genera that have previously been placed in Vernonia can be partially distingushed by the following key. Its utility is limited by the number of segregates of tropical African Vernonieae that remain untreated.

We wish to thank Alice Tangerini, Staff illustrator of the Department of Botany, National Museum of Natural History for the line drawings of the leaves and corollas of Hoffmannanthus and Jeffreycia. We also thank Ingrid Pol-yin Lin of the Department of Botany for the scan of the isolectotype of Vernonia brachycalyx O. Hoffm. designated here as the neotype of Vernonia abbotiana O. Hoffm. Thanks also to the editor, Alexander Sennikov, for many careful observations and corrections.