Vernonieae (Asteraceae) of southern Africa: A generic disposition of the species and a study of their pollen

Abstract Current and previously included members of the Tribe Vernonieae (Asteraceae) of southern Africa are listed in their presently recognized genera with complete synonymies and keys to genera and species. The genus Vernonia, as presently delimited, does not occur in Africa. Genera of the Vernonieae presently recognized from southern Africa are Baccharoides, Bothriocline, Cyanthillium, Distephanus, Erlangea, Ethulia, Gymnanthemum, Hilliardiella, Oocephala, Orbivestus, Parapolydora, Polydora, Vernonella, Vernoniastrum, plus two genera that are named as new: Namibithamnus and Pseudopegolettia. Twelve new combinations are provided and two species, Vernonia potamiphila and Vernonia collinii Klatt., hom. illeg., remain unplaced because of a lack of material. Pollen types are illustrated including previously recognized types: non-lophate, sublophate, tricolporate lophate, and non-colpate triporate lophate. A type previously unknown in the Asteraceae is described here and in a separate paper for Oocephala and Polydora; a non-colpate pantoporate lophate type with pores not strictly equatorial.


Introduction
Attempts to revise the generic concepts of the tribe Vernonieae (Asteraceae: subfamily Cichorioideae) in Africa have proven diffi cult, but it is now possible to resolve nearly all of the generic limits within the tribe in the more limited area of southern Africa here defi ned as including the following: Botswana, Lesotho, Namibia, Republic of South Africa, and Swaziland. Th is treatment is the latest in a series of papers revising the generic limits in the Vernonieae, a series that includes an initial summary of eastern hemisphere taxa (Robinson 1999a), a summary of western hemisphere taxa, (Robinson 1999b), the Vernonieae of China (Robinson and Skvarla 2010) and the Vernonieae of Th ailand (Bunwong et al. 2014). As elsewhere in the series, changes are necessitated by the discovery of the natural limits of the genus Vernonia Schreb., typifi ed by V. noveboracensis (L.) Michx., which is now known to be almost entirely restricted to North America (Robinson 1999a, b) and is native only in the western hemisphere. Th us, many older as well as recent generic segregates in the tribe are now recognized. In addition, in this treatment, two genera are described as new, older names are recognized for two species, and new combinations are provided for 13 species that have previously been placed in Vernonia. Th e pollen of the revised southern African genera is described and illustrated. During the course of the study a new species of Gymnanthemum has been found and described elsewhere ) and a previously unknown form of pollen for the Asteraceae has been recognized (Robinson and Skvarla 2014).
Th e initial reference used for members of the Vernonieae in southern Africa was Flora Capensis by Harvey and Sonder (1894). Additions have been made using Jeff rey and Leistner (2000), Pooley (1991) and Retief and Hermann (1997), and especially Arnold and De Wet (1993). Also helpful were the treatments of Flora Zambesiaca (Wild 1978a, 1978b, Wild and Pope 1977 and Madagascar . Subtractions from the Vernonieae, as listed by Harvey and Sonder, include the discovery that Corymbium L., Hoplophyllum DC., Litogyne Harv., and Platycarpha Less. are not members of the Vernonieae. According to the latest molecular phylogenies (Keeley and Robinson 2009;Funk et al. 2009), Corymbium is in the tribe Corymbieae, at the base of the subfamily Asteroideae, Hoplophyllum is in the tribe Eremothamneae in the subfamily Cichorioideae, Litogyne is in the tribe Inuleae in the subfamily Asteroideae, and Platycarpha is in the tribe Platycarphaeae in the subfamily Cichorioideae. Th e fi rst three of these genera have totally non-lophate pollen (see below). In southern Africa, the Vernonieae now contain 13 genera. Th ese include Ethulia, recognized by Harvey and Sonder, plus the various old and new segregates of Vernonia sensu lato, i.e. Distephanus Cass., Gymnanthemum Cass., Hilliardiella H. Rob., Oocephala H. Rob., Vernonella Sond., Orbivestus H. Rob. and Parapolydora H. Rob. Also present in southern Africa, but with species not listed by Harvey and Sonder (1894) are Polydora Fenzl, Bothriocline Oliv. ex Benth. in Hook., Cyanthillium Blume, and Erlangea Sch. Bip. Most of the taxa involved in the study are found in southern Africa, but a few species are mentioned that are not known from southern Africa but occur in Angola, Mozambique or Zimbabwe, and many subspecifi c taxa mentioned in synonymies are based on type specimens that were not collected in or near southern Africa.
Some of the proper generic dispositions were established in various papers such as Robinson and Kahn (1986) dealing with Distephanus Cass. plus one species of Gymnanthemum, and by Robinson (1999a) dealing with many genera of the paleotropical region. Some of the genera have been discussed in individual papers, Parapolydora in Robinson (2005) and Robinson and Funk (2011), Orbivestus in Robinson (2009) and Vernonella in Robinson and Skvarla (2010a). Th e present paper disposes of all but two of the southern African species now known that were previously placed in the genus Vernonia.

Material and methods
In the following treatment, each genus is described or redescribed with general habit, types of vegetative trichomes, head structure, achene setulae and other trichomes, idioblasts and raphids, pappus form, and pollen form. Secondary metabolite chemistry is indicated based on data from two rather extensive summaries of constituents in the tribe by Bohlmann and Jakupovic (1990) and Herz (1996).
Figures are numbered in the order of the taxonomic treatment. Among the characteristics used in the classifi cation, some special comments are in order.

Trichomes
Th e trichomes of the African Vernonieae may be simple or with transversely affi xed cap-cells as indicated below in the key and descriptions (Robinson 1999a). Th ere are no stellate or goblet-formed trichomes such as those found in the American Vernonieae of the subtribe Piptocarphinae (Robinson 1999b).

Pollen variation
Th e pollen is complicated, showing variation from nearly non-lophate to sublophate or lophate with or without colpi (Figs 3,4,8,10,14,16,18,19,21,22,24,25; see Appendix A for defi nitions). In addition, grains show various degrees of loss of the perforated tectum. Th e structure of the muri and distribution of columellae also varies, and there is a variation from the usual tricolporate or non-colpate triporate conditions to a previously unknown form with pores greater in number and non-equatorial in distribution known as pantoporate.
Regarding the lophate condition, in reality, none of the grains in the Vernonieae has completely evenly spaced spines or columellae, and thus none are completely non-lophate. Lophate, in the Vernonieae, is defi ned as: pollen having the perforated tectum non-continuous in the intercolpar areas ( Fig. 3A-E, 4A, B, D-F). In what is called lophate in many Lactuceae or Arctoteae taxa, the perforated tectum is always continuous in all non-colpar areas. Th is same structure in the Vernonieae is called sublophate: having the perforated tectum continuous between the colpi, supported by massive columellae or baculae, with spines being almost always present over the baculae. Th ese sublophate forms diff er from truly non-lophate forms in having the arrangement of the spines somewhat to distinctly uneven, leaving incipient lacunae. Examples of this sublophate morphology are seen in southern African Vernonieae in In Gymnanthemum (Fig. 10A-C), the incipient lacunae in the intercolpi are in a pattern of 1-2-2-1, a pattern like that seen in the fully developed lacunae of lophate colpate grains in Linzia and Baccharoides. Th e pollen of Gymnanthemum might be referred to as lophate in other tribes. Its grains are totally radially symmetrical. Th e baculae in all of these sublophate forms are freestanding and are fi rmly attached to the footlayer. All of these above mentioned grains also seem to grade into forms of lophate grains that are highly perforate and spinose. Th ese grains are referred to here as sub-echinolophate ( Fig. 4G-I, 10A-C, 14A-F, 19A-C, 24A-F).
In addition to the sublophate pollen types described above, there are many variations of lophate grains, grains with 'perforated tectum lacking' to various degrees in the lacunae or even on the muri. Of these lophate types, one variant, represented by Baccharoides (Fig. 3 A-I), Bothriocline ( Fig. 4 A-C) and Cyanthillium , has prominent highly perforate lophae (muri) with sharply projecting spines. Th e lophae and supporting thickened columellae or baculae are similar to those in the mentioned above: Distephanus, Gymnanthemum, Hilliardiella, Orbivestus, and Pseudopegolettia. Th ese grains are termed echinolophate . A variant of the echinolophate types is seen in Linzia where the surface of the lophae is highly perforate and supported by massive columellae or baculae, but is without spines and is classifi ed as psilolophate (Fig. 16A,B,D).

Pollen and Subtribal Classification
Th e most systematically important subdivision among the lophate types of pollen are the strongly colporate types as seen in Baccharoides and Linzia of the subtribe Linziinae (Figs 3 A-H, 16 A-E) as distinguished from the non-colpate porate forms of the genera of the subtribes Erlangeinae or Centrapalinae (see below). Th e Linziinae genera have either a distinct polar lacuna or an orderly arrangement of lacunae at the polar junctures of the three colpi. Th e patterns of distribution of these characters suggest that the sublophate pollen of all members of the Vernonieae may be reversion types from various lophate types. It is thus notable that the lophate types and sublophate types of the Linziinae and Gymnantheminae all have radially symmetrical organization with regular arrangement of lacunae or incipient lacunae in both lophate and sublophate forms. Th e non-colpate lophate pollens of the Centrapalinae and Erlangeinae treated below also have sublophate types that are colpate but have smaller and more irregularly arranged incipient lacunae.
Linzia has baculae that are connected to each other at their bases and have fewer and weaker attachments to the footlayer. Th is latter condition approximates what is referred to as the rhizomate or two-layered lophae in some members of the Erlangeinae and Centrapalinae treated below, and what is common in the New World subtribe Lepidaploinae (Keeley and Robinson 2009) previously placed in the Vernoniinae (Robinson 1999b).
A diff erent pattern is seen in the many members of the subtribes Erlangeinae and Centrapalinae, where in both the sublophate tricolporate and lophate triporate forms, the incipient lacunae of the sublophate forms and the lacunae of the lophate forms are as mentioned above, smaller and in no regular pattern. Th e rather irregular disposition of lacunae is especially noticeable at the poles of the grains. For these latter forms, two other terms must be added, tricolporate sublophate ( Fig. 10A-C) and triporate lophate ( Fig. 4A, B, D-F).
Th e triporate grains in the Erlangeinae and Centrapalinae have subtypes. Cyanthillium  has baculae only at the intersections of the muri or lophae, and Bothriocline ( Fig. 4 A-C), Erlangea (Fig 8 A -C.), and Namibithamnus ( Fig. 16 F-H) have baculae that intrude upon the submural space (the space under the lophae) but tend to leave an ogee-shaped gap in the middle (Fig. 16 F-G). Bothriocline is distinct in the triplet of slightly connected lacunae that represent a minimal incipient colpus ( Fig.  4 A-C). Namibithamnus, Oocephala and Polydora have pollen with greatly reduced perforated tectum and may be completely non-microporate. Oocephala (Fig. 18 B-E) and Polydora ( Fig. 22 A-I) have many evenly spaced baculae or columellae subtending each of the muri or lophae. Th e baculae of these latter two genera are subtended by a continuous "rhizomate" structure that is itself only weakly attached to the footlayer (Figs. 18 F,22 C). Th is structure of the lophae could be described as having two equally thick layers separated by numerous very short evenly spaced columellae. In all of these listed lophate non-colpate genera, the columella or baculae under the lophae or muri tend to be in a single row. Vernoniastrum diff ers by the irregularly aligned or double-rowed columellae under the muri (Fig. 25 I).
Th e genera Oocephala and Polydora have the most distinctive pollen of all genera presently known in the Asteraceae. Th ey have a 5-8-porate condition with pores distributed non-equatorially in noncontiguous (Fig. 18) or sometimes contiguous lacunae (Figs. 18A, B, 22B). Th ese grains are not radially symmetrical but essentially spherically symmetrical or totally asymmetrical, termed pantoporate (Robinson and Skvarla 2014). Th is diff ers from the 6-pores in three equatorial pairs found in the southeast Asian genus Camchaya Gagnep. in Lecomte Chantaranothai 2008, Robinson andSkvarla 2010b).
Th e genera discussed in the section below fall into a number of subtribes. Some genera, from the more basal subtribes (based on DNA studies by Keeley et al. 2007), i.e. Distephaninae (Distephanus), Linziinae (Baccharoides, Linzia), and Gymnantheminae (Gymnanthemum), all have tricolporate pollen grains that are either lophate or sublophate.

Pollen and Chemistry
Th e Distephaninae, Linziinae, and Gymnantheminae, have tricolporate sublophate or lophate forms of pollen and contain elemanolide sesquiterpene lactones as secondary metabolites. In contrast, two of the genera are in the more highly nested subtribe Centrapalinae (Hilliardiella, Parapolydora) and have weakly sublophate, tricolporate pollen and glaucolide/hirsutanolide sesquiterpenes. According to results from DNA studies combined with some obvious relationships based on pollen, two other genera with lophate, pantoporate pollen also belong to the Centrapalinae (Oocephala and Polydora).
Most of the remaining genera in the study, on the basis of DNA, structural or other evidence are presently placed in the subtribe Erlangeinae (Bothriocline, Cyanthillium, Erlangea, Ethulia, Namibithamnus, Orbivestus, Pseudopegolettia, and Vernoniastrum) which includes all the genera that contain the non-sesquiterpenoid 5-alkylcoumarin secondary metabolites.

Disposition of the genera of southern African Vernonieae into subtribes
Most notable secondary metabolites, sesquiterpene elemanolides (Bohlmann and Jakupovic 1990, as Vernonia anthelmintica (L.) Willd., V. hymenolepis A. Rich., V. lasiopus O. Hoff m.), eudesmanolide (Bohlmann and Jakupovi 1990, as Vernonia adoensis Sch. Bip. ex Walp.). Distribution. Angola, also cited from SW Africa, but that locality probably not intended in the restricted sense. Note. Th e species is known from photographs of types and from descriptions deposited at US by C.E. Smith. Th e type photographs -as well as Fig. 1 B (for corollas) -clearly show the corolla form and fl attened pappus bristles of Baccharoides, and the species is not accounted for elsewhere. Th e type specimen of Vernonia benguelensis is collected in Angola, ad lacum de Ivantola, Feb. 1860, Welwitsch 3276b (BM, photo seen). Th e lectotype of Vernonia limosa is cited as Südwest Afrika, am Longa unterh. Chijija, Jan. 1900, Baum 624 (BM, photo seen; Smith 1917). Th is locality is situated in Angola (Figueiredo et al. 2009

Resources. Traditionally treated as part of Vernonia.
Descriptions. Annual or short-lived perennial herbs to 1 m tall; stems erect or spreading; hairs symetrically or asymetrically T-shaped with short stalk. Leaves alternate; petioles narrow; blades membranaceous, ovate to narrowly lanceolate. Infl orescences terminal, moderately densely to laxly branching, distinctly cymiform or with rather corymbiform branches, with minute bracteoles; peduncles rather short to elongate. Heads narrowly campanulate, involucral bracts ca. 30 in 3(-5) series, gradate, thinly chartaceous, green with pale or purplish margins, persistent, often with pilose to sericeous pubescence; receptacles epaleaceous. Florets 15-94 in a head; corollas bluish to lavender, funnelform with slender lower tubes, throat a third as long to nearly as long as lobes, lobes with simple hairs especially near tips; anthers without tails; apical appendages oblong-ovate, glabrous, with thin cell walls; style base with broad node; style branches with acicular sweeping hairs. Achenes 5-ribbed, or terete, setulae shortly cleft at tips, with idioblasts, sometimes with glands, raphids elongate; inner pappus of many long, sometimes rather fragile, slender-tipped capillary bristles, outer series of persistent squamellae, one species with callose ring. Chromosome number n = 9, 18, 20 (Turner and Lewis 1965, Mathew and Mathew 1976, Jones 1979.
Pollen ca. 30 μm in diameter (dry); triporate, echinolophate, ca. 21 lacunae rather irregularly disposed at poles and in intercolpi; perforated tectum restricted to ridges of muri, with distinct microperforations; spinules of muri short, shorter than width of mural ridge, pointed, without columellae under each murus; baculae single at junctures of muri and no baculae between junctures, each intersection of muri with stout columella that is fi rmly attached to footlayer ( Fig. 4

D-F).
Notable secondary metabolites, 5-alkylcoumarins, sesquiterpene glaucolides, guanolides (Bohlamnn and Jakupovic 1990, as Vernonia chinensis Less., V. cinerea Less.). Resources. For discussion and numerous transfers of species see treatment by Robinson and Kahn (1986). For a recent treatment of the genus in southern Africa see Swelankomo and Manning (2014).
Pollen: 30-36 μm in diameter (dry); tricolporate, sublophate to lophate; lophate forms with muri projecting as spurs into colpus, with echinate or with nearly psilate ridges; tectum continuous in intercolpi and at poles, or in pockets surrounded by ridges, with distinct perforations; with columellae under spines or with muri granular inside, without distinct baculae (Figs. 4 G-I).
Pollen ca. 47 μm in diameter in fl uid, lophate, triporate, with group of polar lacunae, perforated tectum restricted to muri, bacculae centered at junctures of muri, leaving ogee-shaped gaps under the centers of the muri (Figs. 8 A-C).

Key to the species of Erlangea
Descriptions. Annual or short-lived perennial herbs, rarely rhizomatous; stems terete and usually striate, with broad solid pith; hairs uniseriate with erect apical cells, with glandular dots. Leaves alternate, sessile or short petiolate; blades thinly herbaceous, ovate to linear lanceolate, base cuneate or continuous onto stem, margins subentire to serrate or dentate, apex acute to obtuse, surfaces glabrous to densely pubescent; venation pinnate with ascending secondary veins. Infl orescence terminal, corymbiform to rather cymiform, lower bracteoles a reduced foliiform, peduncular bracteoles fi liform. Heads rather small, with broadly campanulate involucres; involucral bracts 15-40 in 2-3 usually subequal series; receptacle fl at or slightly convex, epaleaceous. Florets 3-100 in a head, strongly exserted; corollas white or pink to purple, with glandular dots on surface, with a narrow cylindrical base, limb narrowly funnelform to narrowly campanulate; lobes lanceolate, without apical hairs; bases of anther thecae rounded, not tailed; apical appendages glabrous; style base without node; branches with sweeping hairs shortly acute. Achenes cylindrical with 2-6 usually paler ribs, sides with glandular dots, rarely with short white setulae; raphids short-oblong; pappus lacking or a coroniform rim. Chromosome number n = 10, 20 (Pilz 1980;Gilbert and Jeff rey 1988).
A special eff ort has been made to resolve the endemic southern African element of Gymnanthemum that includes G. corymbosum and G. capense (Swelankomo et al. 2015).
Key to the species of Gymnanthemum  (Fig. 2D).
Th e type specimen was distributed as Vernonia trifl ora Brem., which diff ers by having only 3 fl orets in its capitula, stiffl y and densely hispid stems, and ovate to oblong leaf blades with hispidulous abaxial surfaces.
Most notable secondary metabolites, sesquiterpene germacranolides, elemanolides (Bohlman and Jakupoic 1990, as V. glabra Vatke & V. melleri Oliv. & Hiern).  Descriptions. Small aromatic shrubs to 1.5 m tall; stems, leaves, involucral bracts densely yellowish gray tomentellous or sericeous with crowded T-shaped hairs, hairs with slender 0-2-septate short stalks and small naviculiform or rather elongate cap-cells. Leaves alternate, short-petiolate, with small axillary fascicles usually present, more crowded proximally, smaller distally; blades 5-12 mm long, oblong to obovate, with undulate entire to coarsely dentate margins, basal pair of secondary veins scarcely evident or evident and strongly ascending, minute glandular dots densely disposed on both surfaces. Infl orescences appearing shortly scapose, with numerous pedunculate heads in a corymbiform or partly subumbellate arrangement. Heads campanulate, 6-7 mm wide and high; involucral bracts ca. 60 in ca. 6 strongly gradate series, persistent, oblong ovate with narrow apiculate tips, yellowish with reddish patch or midvein below tip, margins entire, broadly and distinctly thick and pale; receptacle convex, pitted with broad pale network of ridges. Florets 35-40 in a head. Corollas purple, narrowly funnel-shaped from a slender basal tube; throat twice as long as the erect, linear lobes, outer surface of base and throat mostly glabrous, lobes densely glandular-dotted; anther thecae narrow, slightly longer than throat, bases without tails, apical appendages shortly oblong-triangular, glabrous, with thin cell walls; style base with narrow annuliform node; with acicular sweeping hairs almost completely restricted to style branches, a few at top of shaft. Achenes 5-costate, with setulae not divided at tips, surfaces with numerous ungrouped idioblasts, raphids elongate; carpopodium turbinate, glabrous; pappus of ca. 35 slender persistent bristles, bristles as wide at tips as at base, densely scabrid on margins and outer surface, outer series of distinct, smooth, lanceolate scales. Chromosome number unknown.
Pollen ca. 45 μm in diam. in fl uid, lophate, triporate, not echinate, perforated tectum restricted or lacking, crests of muri sparsely papillose (Fig 16 F-H). Descriptions. Low, much-branched shrubs to 1 m high, stems with L-shaped hairs on multiseptate stalks, cap-cells one-armed. Leaves alternate, sub-sessile, linear to elliptical, sometimes serrate. Infl orescences corymbiform cymes, with usually shortly pedunculate heads or with heads sessile in apical clusters of leaves. Involucre ovoid or cylindrical; bracts 20-40 in 4-7 gradate series, ovate to oblong, appressed; receptacle without pales. Florets ca. 10-15 in a head; corollas white or lavender, tubular to narrowly funnelform, throat as long as lobes, tips without hairs or with few short biseriate hairs; anther bases rounded, apical appendages glabrous, with thin-walled cells; style base with narrow ring; style branches with acicular sweeping hairs. Achenes weakly 8-ribbed, sericeous with many setulae, idioblasts numerous, raphids narrowly elongate; pappus biseriate, outer shorter and broader, inner setiform, subplumose, glabrous near base. Chromosome number unknown. Pollen 7-8-porate, with pores scattered over the whole surface in lacunae that are usually not adjacent, lophate (Fig. 18 A-F), minutely papillose on muri, nonperforated tectum restricted to muri, emicropunctate, baculae regularly spaced in single row under muri or lophae, baculae subtended by "rhizomate" structure that is as broad as the outer layer, and gives the muri or lophae a two-layed structure with small evenly spaced columellae separating the layers. Th e rhizomiform base of the muri is weakly attached to the footlayer thus causing muri to easily detach from the core of the grain. Lacunae of exine of pentagons mixed with hexagons. Th e structure of the bucky ball was a remarkable close approximation of the structure of the pollen. It was study of the toy ball that led to the conclusion that the pollen characteristically had seven or eight pores. Other pollen grains show a somewhat diff erent pattern of pores, where pores occur in pairs, one each in a pair of adjacent lacunae (Fig. 18 B). Th e polyporate, subspherically symmetrical, rhizomate form of pollen in Oocephala is shared in a somewhat less symmetrical form by Polydora, but as far is currently known, these Oocephala and Polydora grains, with their non-equatorial pores, are unique in the Asteraceae (Robinson and Skvarla 2014).

Key to the species of Namibithamnus
Notable secondary metabolites: sesquiterpene glaucolides (Bohlmann and Jakupovic 1990 as Vernonia staeheleinoides Harv.). Descriptions. Subshrubs to small shrubs with erect stems from a woody base, not or sparsely branched between base and infl orescence; hairs T-shaped. Leaves alternate, usually decrescent upwardly, sessile or short petiolate, blades elliptical or ovate to oblanceolate, mostly 4-9 cm long, 2-5 cm wide, base short-obtuse to acuminate, margins scarcely repand-dentate, apex short-acute, upper surface with small spinules and few small hairs, lower surface paler, grayish with slender hairs and partially sunken glandular dots; venation pinnate, with up to six or eight lateral veins each side, spreading at 45-60º angles. Infl orescences with leaves of main axis only somewhat to greatly reduced, with only minute bracteoles on branches. Infl orescence shape broadly corymbiform or cylindrical with rounded to fl attened top, with lower heads appearing sessile as result of proliferation by immediately subtending branches forming seriate or scorpioid cymes, branches of infl orescence tomentose with T-shaped hairs. Heads broadly campanulate, 4-14 mm high and wide; involucral bracts mostly persistent, innermost somewhat deciduous, ca. 50-100 in 5-7 series, strongly gradate, 1-8 mm long, 1.0-1.5 mm wide, ovate to oblong, subacute and mucronate to apiculate at tip, innermost acute, tips appressed, margins membraneous and irregularly denticulate distally, often reddish, with dark median keel extending to apex, scarcely thickened and greenish near keel, with numerous small T-shaped hairs except at margins. Receptacle epaleate and tuberculate. Florets 15-ca. 50 in a head; corollas purplish, narrowly funnelform, 4-8 mm long, with sparsely scattered glandular dots, tube slender, 2-3 mm long, throat 1.5-2.5 mm long, lobes 1.0-2.5 mm long, linear-lanceolate, erect, not recurving, sparsely glanduliferous to distinctly or minutely scabridulous outside, without longitudinal internal ducts fi lling lobe; anther thecae 1-2 mm long, without glandular dots, calcarate and with long tails at base, endothecial cells short usually with 2-3 nodes on transverse walls; apical appendage 0.5-1.0 mm long, narrowly lanceolate, often sharply acute; style base with distinct expanded node; sweeping hairs on style branches and scarcely extending on to upper style shaft, slender and narrowly acute. Achenes 1.5-2.0 mm long when mature, 5-costate, with few to many setulae when young, often glabrous at maturity, often with numerous glandular dots on sides between costae, surface with numerous idioblasts that are not joined in series, with narrowly rhomboid raphids internally; carpopodium stopper-shaped to slightly turbinate, with many series of small thick-walled cells; inner pappus of 25-30 slender capillary bristles, rather fl attened outside and barbellate on sides, tips only slightly narrowed, outer pappus of narrow scales 0.5-1.5 mm long. Chromosome numbers n = 10, 18, 20 (Mangenot and Mangenot 1962;Bhandari and Singhvi 1977;Morton 1993). Pollen grains ca. 50 μm in diameter in fl uid, type A, sublophate, tricolporate, echinate, with perforated tectum continuous between colpi (Fig. 19 D-E). Th e grains may also be somewhat asymmetrical (Fig. 19 A).
Th e genus is almost alone in the eastern hemisphere in its seriate cymes, often referred to as scorpioid cymes. Such infl orescences are common in the western hemisphere Vernonieae, occurring in Vernonia itself.
Single species in the flora area  ender, without hairs, basal tubes narrowly funnelform, glabrous, throats about as long as linear lobes, few glands on throat and glands clustered at lobe tips; thecae of anthers without tails at base; apical appendages ovate-lanceolate, glabrous, with thin-walled cells; style base with distinct annular node; style branches with long acicular sweeping hairs scarcely extending below base of branches. Achenes weakly 8-10-veined, with setulae becoming long and uniseriate from near middle or near base, rarely with one long cell and one short cell, idioblasts numerous from base to top of achene, raphids elon-gate; pappus white or grayish, inner series of many barbellate bristles, not broadened at tips, outer series of numerous, short, linear scales. Chromosome number unknown. Pollen ca. 50 μm in diam., sublophate, echinate (Type A), tricolporate, sub-echinolophate ( Fig. 21 A-D).
Key to the species of Parapolydora   Resources. Some species of the genus are treated by Pope (1986). Descriptions. Mostly annuals; stems with L-shaped hairs bearing elongate onearmed cap-cells. Leaves alternate. Infl orescence a thyrsoid panicle with corymbiform cymose branches bearing pedunculate heads or a single terminal head. Involucral bracts ca. 80 in ca, seven series, often with widely scarious margins and awns often black at tips; receptacles epaleaceous. Florets ca. 30 in a head; corollas whitish to purplish, basal tube long, narrowly funnelform distally, throat as long as the narrow glabrous lobes; anther bases plain, not tailed; apical appendage glabrous, with thin cell walls, sometimes weakly ornamented; style base with distinct annular node; branches with acicular sweeping hairs. Achenes 5 or 8-10-ribbed, setuliferous with setulae scarcely divided at tips, idioblasts present but not grouped, raphids elongate; pappus with copious barbellate setae, greenish, yellowish or tawny, rarely white, outer pappus short, squamiform. Chromosome number n = 9, 10 (Jones 1979, 1982, Ayodele 1999. Pollen lophate with ca. 32 lacunae, with fi ve or more pores that seem to be rather asymmetrically distributed on the grains; the pores occur in lacunae that, in a few cases, are adjacent; margins of muri minutely echinate to psilate, without micropunctations, baculae closely spaced in single evenly spaced row under each murus, baculae in turn subtended by "rhizomate" structure that is weakly attached to the footlayer, the muri thus easily stripping away from the footlayer (Fig. 22 C). Th e pollen of Polydora proves to have a lophate condition with well-defi ned lophae or muro bearing 4-5 spinules on each segment. Th e lophae are subtended by columellae in a single series not leaving an ogee-shaped gap in the middle.
Notable secondary metabolites: sesquiterpene lactone glaucolides/hirsutanolies (Bohlmann and Jakupovic 1990, as Vernonia poskeana Vatke & Hildebr.), elemanolides, eudesmanolides, secoglaucolides (Herz 1996, as Vernonia poskeana Vatke & Hildebr. Polydora angustifolia is the species with which Steetz fi rst introduced the use of pollen structure in the taxonomy of the Asteraceae (Steetz in Peters 1864). Th e generic name Crystalopollen was based on the lophate pattern of the pollen observed by Steetz. Descriptions. Small perennial herbs; stems erect, with short branchlets from lower nodes, puberulous to subsericeous with short-stalked hairs bearing asymmetric cap cells, stalks moderately broad with one or two septae, cap cells short and stout, attached near lower end. Leaves alternate, oblong to linear, essentially sessile, sparsely puberulous, abaxially densely glandular punctate. Infl orescence terminal with 1 or a few heads borne on long peduncles. Heads campanulate, 1.7-2.5 cm. wide; involucral bracts 20-60, in ca. three series, subequal, linear-lanceolate, herbaceous with slender tips, pilosulous outside; receptacle slightly convex, surface with angular thickenings. Florets 15 or more in a head; corollas purple, ca. 1 cm long, narrowly funnel-shaped from a slender base, throat slightly shorter than the moderately distorted, linear-lanceolate lobes, outer surface with short glands on tube and throat, spiculiferous distally on lobes; anther thecae narrowed at base to short lobulate tail; apical appendage glabrous, ovate with rather fi rm cell walls; style base with narrow annular node; sweeping hairs acicular, restricted mostly to style branches, few on upper shaft. Achenes mostly 6-8-ribbed, to 4.5 mm long, with glandular punctations and scattered idioblasts on sides, rarely without or with many short setulae that are not or scarcely split at apex, inner layer without raphids or with subquadrate raphids, with layer of rather sclerifi ed narrow cells appearing as striations under the glands and idioblasts; carpopodium broadly stopper-shaped, sometimes with few short uniseriate hairs on inner surface; pappus of ca. 40 scabrid bristles, mostly in one series, as long as tube and throat of corolla, rather easily deciduous, scarcely narrowed except at tips, with few indistinct short bristles in outer series. Chromosome number unknown.
Th e genus consists of mostly monocephalous species, but those species have many individual diff erences such as the restriction of leaves to a basal rosette, capitula structure, and pubescence of the achenes. Th ey do have essentially identical pollen, but it is a widely distributed pollen type in the Erlangeinae. Th ere are no unique or uncommon characteristics that the two species share.   Descriptions. Annual or perennial herbs 0.3-1.0 m tall; stems pilose, hairs simple with elongate apical cells with slightly asymmetric bases. Leaves alternate. Infl orescence with 1-many heads. Involucre campanulate; involucral bracts ca. 50 in ca. three series, gradate, persistent; receptacle epaleaceous. Florets ca. 50 in a head; corollas reddish-purple, basal tube narrowly funnelform, throat shorter than lobes or anther thecae, lobes pilosulous distally; anther bases acuminate to acutely tailed; apical appendage glabrous, with thin cell walls. Style base with node; style branches with acicular sweeping hairs. Achenes 4-6-angled, setulae aparse on sides, idioblasts usually grouped in transverse bands, raphids elongate; pappus bristles subpersistent, marginally densely barbellate; outer squamae persistent. Chromosome number n = 10 (Jones 1979(Jones , 1982. Pollen triporate, lophate, perforated tectum discontinuous in lacunae, muri papillate, with or without micropunctations on muri (Fig. 25 D-I).
With habit similar to Polydora but often perennial, lacking L-shaped hairs, having tailed anther bases, and a chromosome number n = 10. Also characteristic of the core element of Vernoniastrum are the transverse bands of crowded idioblasts in the achene walls.
Key to the species of Vernoniastrum   Resources. Species reviewed by Smith (1971) and Robinson and Skvarla (2010a). Descriptions. Annual or perennial herbs, with leaves rosulate or on leafy stems, basal rosettes often withered at anthesis, bases of plants erect, with or without a dense basal cloak of hairs. Hairs simple or lacking on stems. Infl orescences monocephalic, laxly cymose or densely corymbiform, with short to very elongate peduncles. Heads broadly campanulate; involucres 3-6-seriate, bracts broadly to narrowly oblong, gradate with basal bracts often more lanceolate, tips of inner bracts often obtuse to rounded or apiculate, distally and marginally rather scarious, often purplish. Florets 10-50 or more in a head; corollas purple, with long slender basal tube, throat short, not noticeably broadened at base, lobes linear, usually contorted with age, bearing glands, simple hairs, or L-shaped to T-shaped hairs; anther thecae calcarate and blunt at base, without tails; apical appendage oblong-ovate, with thin cell walls; style base with annulus of thickened, quadrate cells; sweeping hairs slender with sharp, narrow tips. Achenes with ca. 10 ribs, setulose on ribs, setulae with paired cells separated in distal third or less, with numerous idioblasts on surfaces between ribs; raphids in achene wall narrowly elongate. Chromosome number n = 9 (Jones 1982).
Th e genus Vernonella is most notable for its often solitary heads, simple vegetative hairs, the comparatively limited diff erentiation of the involucral bracts, unexpanded corolla throats, and the comparatively small sublophate rather than lophate pollen with uniquely truncated colpi. On the basis of the examination of the type species, the detailed studies of Smith (1971), and reviews of literature, eleven species are recognized in the genus. Th e genus is restricted to Africa and is distributed from Cameroon and Sudan in the north southward to Natal in South Africa.

Distribution. Natal.
Note. Material of the species was sought by Smith from its type locality, but he reported (1971), "I searched the type locality for living plants, but the area is now devoted to sugarcane fi elds, and the species may have been completely eliminated." Species not yet properly placed in a genus
Descriptions. Th e initial assumption, based on the robust habit and the described yellowish brown velutinous pubescence of the stems, was of a relationship to the genus Gymnanthemum of the subtribe Gymnantheminae. Other features indicate a diff erent relationship. A high resolution image of an herbarium specimen (PRE; Fig 2D) as well as an illustration (Fig. 26), show a somewhat keeled involucral bract with a dark median stripe, a character not found in Gymnanthemum. In addition, the pollen totally lacks the strongly developed sublophate pattern that is characteristic of Gym-  nanthemum (Figs. 10 A-C) and instead is sublophate with small incipient lacunae (Fig.  27). Th e pollen and involucre characters seem to indicate a position in the subtribe Erlangeinae. Th is is most likely a new genus but without a more comprehensive study of the more northern members of the African Vernonieae we can only say that V. potamophila, while defi nitely not a true Vernonia, is unplaced as to genus.
An examination of limited fragments showed a few additional characters. Th e abaxial surface of the leaf has a tomentum of long-armed T-shaped hairs and sweeping hairs restricted to the branches of the style and the juncture of the branches at the shaft of the style. Th e lobes of the corolla had areolae that were reminiscent of the ducts in the corolla lobes of true Vernonia, but the areolae do not form continuous elongate ducts. Raphids of the achenes were short-rectangular in elongate cells. Chromosome number unknown.
Distribution. Transvaal (In cliv. Mont. Elandspruitbergen, alt. 7000 ped., leg. R. Schlechter, 2 December 1893, N. 3832). Note. Th e name is an illegitimate later homonym and cannot be used, but the species, as described, cannot be placed with other Vernonian species presently known from South Africa. Th e original description (Klatt 1896) makes no mention of corollas and they may have been absent on the type collection. According to the description, the achenes are ca. 3 mm long and the pappus is 1.5 cm long, suggesting an immature or overly mature condition. From the description it is not certain the species is actually a member of the Vernonieae.