Systematics and Geography of Plants

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Strombosia fleuryana, a new species from Ngomo on the Ogooué River in West Gabon is described and illustrated. The species is distinguished from the other Strombosia species of Lower Guinea by its leaves with very short petioles and by the subsessile flowers. A key to all Strombosia species of Lower Guinea is presented.
 
The tropical African genera Brachystephanus Nees and Oreacanthus Benth. are revised. A detailed morphological survey indicates that only a single genus is involved, the name Brachystephanus having priority. A new taxonomie treatment is therefore proposed with Brachystephanus sensu lato divided into three sections: sect. Brachystephanus, sect. Oreacanthus and sect. Pseudoreacanthus. The closely allied American genus Stenostephanus Nees is compared using both available morphological and molecular data. In the newly circumscribed Brachystephanus, 32 taxa within 22 species are presented among which six new species, two new subspecies and two new varieties are described here, together with new combinations or names for four taxa and a new status for two taxa being formalised. Keys to identification and descriptions are presented for each taxon together with notes on habitat and ecology, distribution, phytogeographical considerations and herbarium specimen citations, supported in many instances by illustrations. Pollen analysis with accompanying SE micrographs is provided for 21 taxa. The occurrence of plietesial life cycles, myrmecophily and gynomonoecy within the genus are discussed, together with a summary of the conservation significance of Brachystephanus. © 2009 National Botanic Garden of Belgium Permission for use must always be obtained from the National Botanic Garden of Belgium.
 
Fifteen names of taxa in the genus Elaphoglossum Schott ex J. Sm. (Elaphoglossaceae) are here lectotypified in order to stabilize the names. All these names apply to leptosporangiate ferns from the Neotropics. The typification allows a correct nomenclature of the Neotropical Elaphoglossum species. Specimens designated as lectotypes are kept in the three herbariums of Berlin (B), Brussels (BR) or Paris (P).
 
In order to compile a "Catalogue of neophytes in Belgium (1800-2005)" collections of vascular plants in the main Belgian herbaria (public as well as private) were thoroughly revised. This revision considerably enlarged the current knowledge of the alien flora of Belgium and yielded numerous additional taxa. On the other hand it has been shown that in the "Nouvelle Flore de la Belgique, du G.-D. de Luxembourg, du nord de la France et des régions voisines" a number of non-native vascular plants have been erroneously or doubtfully listed as having occurred spontaneously in Belgium. The present paper provides information on 30 non-native taxa that need to be omitted from future editions of the Flora of Belgium due to reidentification of herbarium collections. Furthermore several dubious records of non-native plants in Belgium have never been confirmed by herbarium collections and are therefore doubtful; they are listed here but have been omitted from the "Catalogue." Finally, some non-native taxa included in the "Nouvelle Flore..." have indeed been recorded for the neighbouring territories covered by this Flora, but never for Belgium and therefore they were omitted from the "Catalogue." The importance of a thorough herbarium revision as the main basis for the compilation of a catalogue of non-native plants (in stead of literature data) is stressed. Such a revision surely is more time-consuming but, above all, much more accurate and reliable. As such, it yielded 20% additional taxa in the final catalogue. Inversely, almost 3% of the taxa of the original list of Belgian xenophytes needed to be omitted.
 
Aframomum wuerthii from Nyungwe National Park is described as new species, the third of the genus for Rwanda. It is related to A. angustifolium but differs in the carmin- red and membranaceous scales and bracts, and in the white petals.
 
Three new species of Commelina L. (Commelinaceae) are described from south-central Africa. Commelina sphaerorrhizoma Faden & Layton (D.R.Congo, Zambia, Angola) is distinguished by its moniliform rhizome composed of spherical segments, glaucous leaves that are glabrous above and often have cordate-amplexicaul bases, blue flowers and very large, hairy seeds. Its rhizome is similar only to those of the yellow-flowered Commelina crassicaulis C.B.Clarke and C. welwitschii C.B.Clarke, but its one-seeded capsule locules suggest a different, as yet obscure relationship. Commelina orchidophylla Faden & Layton (D.R.Congo) is distinguished by its tuberous roots, orchid-like pair of large basal leaves that are white-tomentose beneath and appressed to the ground, and free-margined spathes. It may be related to other geophytes or hemicryptophytes with free-margined spathes such as Commelina hockii De Wild., C. scaposa C.B.Clarke and C. psuedoscaposa De Wild., but differs from all of them by its large, distinctively pubescent basal leaves. Commelina rosulata Faden & Layton (D.R.Congo) is distinguished by its basal rosette of large, glabrous leaves and clustered, subglabrous spathes with fused margins. It may be most closely related to Commelina transversifolia De Wild., C. grossa C.B.Clarke and C. grandis Brenan, and may be separated from them by its large, broad basal leaves. Commelina praecox T.C.E.Fr. is a new synonym of C. scaposa C.B.Clarke and C. bianoensis De Wild. is a new synonym of Commelina neurophylla C.B.Clarke.
 
The taxonomic history of Santiria Blume is reviewed. A revision of the African material available in eight major herbaria (a total of 187 specimens) is carried out. The material shows that the morphological characters of vegetative and reproductive organs, except the shape of the fruit, tremendously vary in shape, dimensions or pubescence. Intermediate states make it impossible to distinguish different taxa. Consequently, Santiria trimera (Oliv.) Aubrév. is confirmed as the only species of the genus in Africa and therefore redefined. Seven taxa are newly relegated to its synonymy.
 
The African species of Crudia (Leguminosae, Caesalpinioideae) are revised. Ten species, including two new ones, are recognized. The African species of the genus are confined to the Guineo-Congolian region. A key to the species is presented. To facilitate its use, the stipules of all species are illustrated. The fruits, as far as known, are illustrated as well and the distribution maps of all taxa are added.
 
The genus Polysphaeria was only in 2007 recorded for the Gulf of Guinea Islands. A specimen collected on Bioko ('Fernando Po') by Mildbraed in 1911 remained unnamed in the Rubiaceae until 1967 when it was erroneously filed under Coffea. It is in fact Polysphaeria macrophylla K.Schum., also known from the African mainland (Liberia to Cameroon). Polysphaeria macrophylla is easily distinguished from all other species of the genus by the presence of swollen internodes inhabited by ants, an apparent feature overlooked in the past. The species is neotypified and illustrated, and a key to the Guineo-Congolian species of the genus is provided.
 
Crotalaria gracilipes O. Lachenaud, a new species from Central African Republic, is described and illustrated. In its sessile, trifoliolate leaves and lateral inflorescences with very slender peduncles, it is closely related to C. leptoclada Harms and C. sessilis De Wild. The diagnostic characters between the three species are discussed. French Crotalaria gracilipes O. Lachenaud, nouvelle espèce de République centrafricaine, est décrite et illustrée. Par ses feuilles sessiles et trifoliolées et ses inflorescences latérales à pédoncule très grêle, elle est très voisine de C. leptoclada Harms et C. sessilis De Wild. Les caractères distinctifs entre les trois espèces sont discutés.
 
The soil algal flora of limed and unlimed sessile oak (Quercus petraea (Matt.) Lieb.) and Norway spruce (Picea abies (L.) Karst.) forest plots situated in the Belgian Ardenne was investigated. Chlorophyta (61 taxa) were by far the most diverse group, followed by Xanthophyta (ten taxa), Bacillariophyta (three taxa), Cyanophyta (two taxa) and Euglenophyta (one taxon). Elliptochloris incisiformis Hoffmann et Kostikov, Elliptochloris perforata Hoffmann et Kostikov and Dicranochaete terrestris Hoffmann et Kostikov are described as new taxa.
 
The paper presents phytosociological analyses of savannah vegetation infested by Chromolaena odorata and Hyptis suaveolens in the Betecoucou region of the Guinea-Congolia/Sudania regional transition zone of Benin. Some 79 phytosociological plots were analysed according to the Braun-Blanquet method. A total of 199 species of vascular plants have been recorded belonging to 53 families. Hemicryptophytes (4.8%) and geophytes (3.9%) are less abundant in the colonised sites than in the non-colonised ones. The colonised sites are dominated by species that are therophytes (50.8%) or chamaephytes (39.9%). Species that are widely distributed (45.9%), mainly pantropical (26.7%) and paleotropical (18.3%) in distribution, are also more frequent in infested than in non-infested sites. On the contrary, African pluriregional elements, e.g. Sudano-Zambezian species (44.4%) and afrotropical species (16.6%) are more frequent in non-infested than in infested sites. Among the widely distributed species, those that are ruderal or nitrophilous are the most frequent. © 2009 National Botanic Garden of Belgium Permission for use must always be obtained from the National Botanic Garden of Belgium.
 
Two analyses are carried out for a reconstruction of the phylogeny of the large angiosperm family Rubiaceae. The position of Luculia and Coptosapelta, unresolved or sister to all other Rubiaceae in most of the recently published results, is reanalysed by using five plastid and three nuclear DNA regions sequenced for selected Rubiaceae taxa. A supertree is constructed for more than 500 species in 300 genera, i.e. ca. 50% of the genera known in the family. The supertree is derived from four source trees based on rbcL, rps16, trnL-trnF and atpB-rbcL, the latter with 106 newly generated sequences. The results are confronted with the morphological, anatomical and biogeographical knowledge of the family and discussed in the light of other molecular phylogenies. It is proposed to recognize only two subfamilies, Cinchonoideae (raphides mostly absent; secondary pollen presentation common) and Rubioideae (raphides present; heterostyly common). Luculia and Coptosapelta are found to be basal to the rest of the Cinchonoideae, which are divided in two newly recognized supertribes, Ixoridinae and Cinchonidinae. Also in the subfamily Rubioideae, two major clades may be distinguished and are recognized as supertribes Psychotriidinae (predominantly woody) and Rubiidinae (predominantly herbaceous); the genus Colletoecema and the tribes Urophylleae, Ophiorrhizeae, Lasiantheae and Coussareeae are basal Rubioideae falling outside these two supertribes. Four alliances are spotted as groups for which major problems exist with regard to relationships and tribal delimitation: three neotropical groups, viz. the Calycophylleae/Condamineeae alliance, the Catesbaeeae/Chiococceae complex and the Rondeletieae alliance, and the pantropical Spermacoceae s.lat. The cladogenesis of Rubiaceae depicted by the supertree is strongly correlated with the present geographical distribution of taxa. The results are summarized in a conspectus of the family enumerating the tribes and listing all their genera for which the inclusion is corroborated by DNA sequences. Newly recognized tribes and subtribes are the Henriquezieae-Posoqueriinae, the Palicoureeae and the Rubieae-Theligoninae and -Kelloggiinae. Some tribes are reduced to subtribes, viz. Virectarieae (subtribe of Sabiceeae), Bertiereae (subtribe of Coffeeae) and Isertieae (subtribe of Cinchoneae). Novel positions are proposed for the genera Aulacocalyx, Calycosiphonia, Cremaspora, Crossopteryx and Morelia.
 
The Leguminosae (Caesalpinioideae, Mimosoideae and Papilionoideae) of Angola were revised and a catalogue of the taxa endemic to the country is presented together with distribution maps. Up to present, 1016 taxa belonging to 166 genera of Leguminosae have been recorded for the flora of Angola. There are 144 native genera and 863 native species. The endemism is c. 19 %, with 185 taxa endemic to Angola, consisting of 165 species and 20 infraspecific taxa. The genera Crotalaria and Indigofera have the highest number of endemics, with 46 and 20 species, respectively. Huíla is the province where more endemic taxa occur, with 83 taxa (44 %) recorded. As shown by the data analysed, 39 endemic taxa (20 %) are only known from the type specimens and 77 (41 %) have not been collected since 1960. A total of 93 names that were recorded in the Flora 'Conspectus Florae Angolensis' as endemics, are either synonyms of widespread taxa or are now known to occur also elsewhere.
 
After the transfer in 2006 of two Anthonotha species to Englerodendron (Leguminosae, Caesalpinioideae), the larger, remaining part of the African genus Anthonotha is divided in two genera: Anthonotha sensu stricto and Isomacrolobium. Triplisomeris is synonymized under Isomacrolobium. The characters to separate the two genera are discussed and illustrated, and summarized in a table. For both genera a list of species is added. For Isomacrolobium it includes three new combinations. © 2008 National Botanic Garden of Belgium. All rights reserved.
 
This study is based on 598 phytosociological relevés and 1021 plant species taken during an extensive vegetation survey in the Republic of Benin. Site selection was primarily directed towards forest reserves to understand the potential vegetation patterns countrywide. Distributional patterns assessed by means of numerical analyses suggested a meaningful subdivision of Benin into ten phytogeographical districts (PDs). Chorological analysis proved to be valuable as a complementary approach to the characterisation of the phytosociologically-defined districts and allowed their merging into three major phytochorological zones, namely the Guineo-Congolian and Sudanian regions, linked by the Guineo/Sudanian transition zone. The phytogeographical patterns described were consistent with the hypothesis of water availability-driven variation in species and chorotype compositions. While the climate in terms of several climate elements was the primary factor, rainfall considered alone failed to explain the observed patterns. The biogeographical particularities of the PD Pobè in southern Benin were elucidated by the exclusive presence of many Guineo-Congolian endemic genera. The PDs Bassila and Atacora Chain turned out to be of great ecological and biogeographical relevance within the Sudanian regional centre of endemism. Evidence is provided for a former floristic connection of these PDs to the West African Forest Blocks. The results show how the phytosociology approach through numerical analyses of a large dataset constitutes an effective methodological tool for clarifying phytogeographical patterns at meso-scale. Moreover, phytosociology and chorology appear as complementary approaches to phytogeography.
 
A species of the genus Inga Mart., Inga edulis Mart. native to Brazil, was introduced twice in Congo-Brazzaville, viz. in 1980 and 1991. The species seems well adapted to the ecological conditions of its new environment and is on the way to naturalisation. French En provenance du Brésil, Inga edulis Mart., une espèce du genre Inga Miller (Leguminosae, Mimosoideae), introduite au Congo-Brazzaville au cours des années 1980 et 1991, s'est bien adaptée aux nouvelles conditions écologiques du Congo et est sur le point de se naturaliser.
 
Surirella bifrons var. intermedia O.Müll. and Surirella fuellebornii O.Müll., including its infraspecific taxa, were re-evaluated using historical East African material collected in the early 20th century from which Otto Müller described more than 100 new diatom taxa. In addition, material from the Hustedt Diatom Collection together with material collected during the past decades in the region of the African Great Lakes was studied. The investigation of the original material of Surirella bifrons Ehrenb. in the Ehrenberg Collection allowed to elevate Surirella bifrons var.intermedia to species rank: Surirella kusberi nom. nov. The variation observed in the material studied supported the abandonment of taxonomic recognition of Surirella fuellebornii f. subconstricta O.Müll. and var. constricta O.Müll. On the other hand, var. tumida Hustedt and var.elliptica O.Müll. are here elevated to species rank: Surirella crawfordii nom. nov. and Surirella friedelhinziae nom. nov. respectively. Finally, Surirella fuellebornii var.worthingtonii H.Bachm. was found to belong within the variability of Surirella malombae O.Müll.
 
In order to compile a catalogue of non-native vascular plants in Belgium the main Belgian public herbaria were revised. During this revision a few cases were encountered where the nomenclature had to be improved. In the present paper Helenium ×clementii (Asteraceae) is described as a new nothotaxon. In addition, the following new combinations are made: Dysphania pseudomultiflora (Chenopodiaceae), Leptochloa parviflora and Medicago monantha subsp. incisa.
 
The inselberg vegetation in the southern part of Centre-Benin was investigated using floristic relevés within plots of 900 m2 each. A total of 108 floristic relevés were performed and 380 plant species recorded. Five types of vegetation were identified: dry forest, woodland, tree savannah, fallow, and meadow. The dry forest remnants are located on inselbergs with deep crevices and depressions between the hill tops. The crevices in rocky area constitute moist pockets. Savannah vegetations colonise the rocky that are covered with topsoil. The species richness ranges from 18 species in the meadows to 227 species in dry forest. Two plant species are to be confined to the studied inselbergs in Benin: Cordia millenii and Urera cameroonensis. The most important plant families were Leguminosae (in particular Papilionoideae), Poaceae, and Rubiaceae. French La végétation des inselbergs du secteur méridional du Centre-Bénin a été étudiée à l'aide de relevés floristiques à l'intérieur de placeaux de 900 m2. Au total, 108 relevés ont été effectués et 380 espèces ont été inventoriées. Quatre types de végétation sont identifiés: la forêt dense sèche, la savane arborée, la prairie et la jachère. Les îlots de forêt dense sèche sont localisés sur les inselbergs à anfractuosités profondes et dans les dépressions intra-rocheuses. Les anfractuosités rocheuses constituent donc des poches d'humidité. Les groupements de savane arborée sont situés sur les inselbergs à dalles rocheuses recouvertes de sols peu profonds. La prairie est localisée sur les inselbergs à dalle dénudée. La richesse spécifique varie de 18 espèces en prairie à 227 espèces en forêt dense sèche. les Cordia millenii et Urera cameroonensis sont deux espèces inféodées à cet habitat saxicole au Bénin. Les familles les plus importantes, par ordre d'importance spécifique, sont les Leguminosae (surtout les Papilionoideae), les Poaceae et les Rubiaceae.
 
A new species of Bertiera (Rubiaceae) from Cameroon and Gabon, Bertiera heterophylla Nguembou & Sonké, is described and illustrated. This new species belongs to the subgenus Bertiera and appears to be closely related to Bertiera bicarpellata. Bertiera heterophylla differs from B. bicarpellata in having lateral branches with terminal inflorescences while on the main stem, the inflorescences are axillary.
 
1: Cosmarium bellum; 2-4: C. cunningtonii; 5-7: C. doidgei var. depressum, 5: holotype; 8-10: C. okavangicum, 8: holotype; 11, 12: C. haynaldii var. africanum, 11: holotype; 13: C. haynaldii var. ambadiense; 14, 15: C. richianum; 16: C. geminatum var. triordinatum; 17: C. taxichondrum var. pentachondrum; 18, 19: C. pseudotus, 19: holotype. Scale bar = 35 µm (fig. 1, 5-16) or 50 µm (fig. 2-4, 17-19).
In the present paper, a sequel to an earlier discussion on desmid algae from the Botswana Okavango Delta and the annexed Namibian Caprivi Strip, 25 taxa belonging to the genera Cosmarium, Xanthidium and Staurastrum are dealt with. Nine taxa are newly described: Cosmarium doidgei var. depressum, C. fuelleborniforme, C. haynaldii var. africanum, C. moremiense, C. okavangicum, C. permaculatum var. bituberculatum, C. pseudotus, Xanthidium micracanthum var. angustatum and Staurastrum okavangicum. The names of four taxa are newly given or recombined: Cosmarium fritschii, C. haynaldii var. ambadiense, C. taxichondrum var. pentachondrum and C. thomassonii. The majority of the taxa discussed can be characterized as African endemics.
 
The effect of exotic tree species on the flora of their undergrowth was investigated in an afforested site of Sèmè in Benin. The main vegetation in the area consists of timber tree plantation and fallow. Widely distributed species were in the majority (68.8% of spectrum) compared to guineo-congolian species (16.9% of spectrum). These plantations were poor in indigenous species and housed an undergrowth quite different from the native flora surrounding the plantations. This impoverishment of the original floristic diversity was related to ecological effects (shallows, litter amount, soil acidity, competition, allelopathy, etc.) induced by exotic trees (Acacia auriculiformis, Acacia mangium, Casuarina equisetifolia and Eucalyptus camaldulensis). In the Acacia plantation, undergrowth was covered by Acacia pods, stems, phyllodes and a litter amount of 21.05 t MS/ha. The Casuarina equisetifolia plantations presented also a high amount of litter and low plant species richness in the undergrowth. Eucalyptus camaldulensis plantations negatively influenced flora diversity through soil acidification and allelopathy. Casuarina equisetifolia alone or in association with Acacia auriculiformis increased the floristic diversity of the undergrowth.
 
Verbena incompacta – representative individual; herbarium specimen collected in Spain.  
Verbena brasiliensis, of South American origin, is reported for the first time from Sukhumi, Georgia. The species is shortly described and depicted. The spread of this weedy to invasive species outside its area of origin is discussed.
 
Ongoing molecular studies of the subfamily Lamioideae have demonstrated that several genera do not correspond to monophyletic groups as currently circumscribed. Leucas R.Br. and Otostegia Benth. are particularly problematic in this respect. To confront the issue of monophyly taxonomically, the genus Rydingia A.-C. Scheen & V.A. Albert is described here with four species formerly assigned to Otostegia. The number of species of Moluccella L. is increased to three with the recognition of Moluccella aucheri (Boiss.) A.-C. Scheen which is transferred from Otostegia. The number of species of Isoleucas O.Schwartz is increased to two with the recognition of Isoleucas somala (Patzak) A.-C. Scheen, which is transferred from Otostegia. It was also necessary to distinguish two different groups of Leucas: 1) Leucas sensu stricto and 2) the "African Leucas clade", which preliminarily may be referred to as Leonotis (Pers.) R.Br. sensu lato due to nomenclatural priority.
 
From the Netherlands four desmid species are newly described: Cosmarium calculus, C. jugatum, C. medioretusum and Roya closterioides. The names of eight taxa are newly given or recombined: Closterium tortitaenioides, Euastrum biscrobiculatum, Staurastrum crassangulatum, S. hirsutum var. arnellii, S. reductum, Staurodesmus cuspidatus var. divergens, Std. extensus var. malaccensis and Std. incus var. indentatus. Taxonomic affinities, habitat characteristics and regional distribution data are dealt with.
 
Coptosperma in Comoro Islands: A, young vegetative internodes of C. mitochondrioides ; 
Coptosperma mitochondrioides : A, inflorescence; B, flower; C, infructescence and vegetative shoot showing “bec de canard” stipules; D, longitudinal section through fruit showing the abortion of one locule and the ruminate seed. A-C, from field pictures by A. Mouly and F. Barthelat; D, from Mouly 610 (P). 
SE micrographs of the seed of Coptosperma mitochondrioides : 
Distribution of Coptosperma mitochondrioides : A, overall distribution map, showing northern Madagascar and Mayotte (arrow); B, detailed distribution map of C. mitochondrioides on Mayotte. 
In the Comoro Islands, Rubiaceae are one of the largest families of flowering plants, represented by 33 genera and sixty species. Among these genera, Coptosperma (Pavetteae, Ixoroideae) is represented by two widely distributed species, also occurring in Madagascar and continental Africa, and a third species new to science. Coptosperma mitochondrioides Mouly & De Block possesses large stipules of the "bec de canard" type and ribbed fruits. While this type of stipule is typical for many Malagasy Coptosperma species, ribbed fruits are very rare within the genus. Within the Comoro archipelago C. mitochondrioides is restricted to Mayotte, but the species is also known from northern Madagascar. The new species is described and illustrated and a key to the species of Coptosperma occurring in the Comoros is provided.
 
Sixty-four species are newly reported from the Republic of Congo. The occurrence of seven species reported without specimen citation by Sita & Moutsamboté (1988), and which constitute important range extensions, is also confirmed and documented. The vascular flora of the Republic of Congo now includes about 4538 species, fifteen of which are endemic. Its diversity nearly compares with that of neighbouring Gabon (4710 species), which, however, has a much higher number of endemics (508 species). French Soixante-quatre espèces sont signalées pour la première fois de la République du Congo. La présence de sept espèces signalées sans indication d'échantillons par Sita & Moutsamboté (1988) et qui constituent d'importantes extensions de répartition, est également confirmée et documentée. La flore vasculaire de la République du Congo comporte environ 4538 espèces, dont quinze endémiques. Sa diversité est donc presque comparable à celle du Gabon voisin (4710 espèces), où le nombre d'endémiques est cependant beaucoup plus élevé (508 espèces).
 
Partial 16S rDNA sequences were determined for six Microcystis strains from lakes in the region of Plön (Northern Germany) assigned to four different species on the basis of their morphology. These sequences appear very similar to each other and to those of 71 Microcystis strains from four continents available in the databases. This great genotypic homogeneity, as measured by 16S rDNA sequence similarity (334 characters), is contrasting with the conspicuous morphological differences observed for the studied strains.
 
Distribution olplots and transects for the three different survey methods used on Mount Cameroon. The positions of the transects have been added to a map originally constructed to show ONADEF and Rapid Botanical Survey plots.  
Advantages and drawbacks of three vegetation survey approaches used on Mount Cameroon. 
Between 1990 and 2000 a number of vegetation surveys were undertaken on the Mount Cameroon area using mainly three methods: 0.25 ha sample plots, 20 m wide transects and rapid botanical surveys. A comparison of these methods in terms of data collected, operational characteristics and output relevance, revealed their strengths and weaknesses. The methods vary markedly in their ecological value (0.25 ha sample plots superior), taxonomic scope and rigour (rapid botanical survey superior) and logistic efficiency (transects superior). The combined outcome of all these surveys is discussed and recommendations made on the use of the rapid botanical survey in order to rapidly fill the remaining gaps on plant distribution. /// Durant la période 1990-2000, une série d'inventaires floristiques a été réalisée au Mont Cameroun. Ces inventaires étaient basés principalement sur trois méthodes: utilisation de placettes d'échantillonnage de 0,25 ha, de layons ou transects de 20 m de large et la technique d'inventaires botaniques rapides. Les points forts et les faiblesses des trois méthodes sont révélés par comparaison des types de données collectées, des caractéristiques logistiques et des résultats obtenus. Les méthodes varient nettement quant à leur valeur écologique (technique des placettes de 0,25 ha étant supérieure), leur rigueur et leur dimension taxonomique (technique d'inventaires botaniques rapides supérieure) et leur efficacité dans la réalisation des opérations (technique des transects supérieure). Les résultats combinés de tous ces inventaires sont discutés et des recommandations formulées pour l'utilisation de la méthode d'inventaires botaniques rapides afin de combler rapidement les lacunes dans la connaissance de la distribution des plantes. Traduit par le journal.
 
Sile du fac Baromhi Mho, vers 300 m d'afrilude dans fe.lfàrêls de l'Oue.l1 Cameroun (d'après Mafey & Brellae f99Xa). (grisé: total des pourcentages des pollens d'arbres; blanc: total des pourcentages des pollens d'herbacées, surtout les Gramineae qui dominent en savane; noir: pollens de Cyperaceae. herbacées aquatiques). 
A phase of climatic disturbance and catastrophic destruction of Central African forests (in the region of south Cameroon, south Central African Republic, Gabon and Congo) occurred 2500 years BP (<sup>14</sup>C). This synchronous event for the different sites studied was manifested in either a brutal extension of the savannas, especially for the sites near the north (West Cameroon) and towards the south (Mayombe) of the Forest Domain, or a brutal extension of pioneer vegetation. Forest reinvasion began from 2000 years BP for some sites, or was a little later for others, according perhaps to the position of residual forests. This reinvasion still continues at the present time. Fires in the peripheral savannas can slow up this reinvasion, but in the long term the forests have continued to transgress into open regions. These major variations in the forest environment are illustrated by the history of two tree species of which numerous data have been able to be obtained: oil palm (Elaeis guineensis) and Okoumé (Aucoumea klaineana). This massive disturbance which culminated about 2500 years BP is contextualised at the global and regional scale in the broader paleoclimatic framework of the upper Quaternary. Concerning climatic change and the dynamics of the monsoon on Central Africa, the key role which has always been played by Sea Surface Temperatures is shown. It is also shown that this vast disturbance which occurred alongside relatively "warm" regional and global conditions could be an "analog" to what could occur in Central Africa during the phase of "Global Warming" predicted for the 21st century. /// Une phase de perturbation climatique et de destruction catastrophique des forêts d'Afrique centrale (secteurs Sud Cameroun, Sud Centrafrique, Gabon et Congo) est survenue vers 2500 ans BP (<sup>14</sup>C). Ce phénomène, synchrone pour les différents sites étudiés, s'est traduit soit par une extension brutale des savanes, surtout pour les sites vers le nord (Ouest Cameroun) ou vers le sud (Mayombe) du Domaine Forestier, soit par une brutale extension des végétations pionnières. La reconquête forestière a débuté dès 2000 ans BP pour quelques sites, soit elle a été plus tardive pour d'autres, suivant peut-être la position des îlots forestiers résiduels. Cette reconquête forestière se poursuit encore à l'époque contemporaine. Les feux dans les savanes périphériques peuvent retarder cette reconquête mais, sur le long terme, les forêts ont toujours transgressé sur les milieux ouverts. Ces variations importantes du Domaine Forestier sont illustrées par l'histoire de deux arbres pour lesquels de nombreuses données ont pu être obtenues: le palmier à huile (Elaeis guineensis) et l'Okoumé (Aucoumea klaineana). Cette vaste perturbation, qui a culminé vers 2500 ans BP, est replacée dans le cadre paléoclimatique plus général du Quaternaire récent, au niveau global et régional. Concernant les changements climatiques et la dynamique de la mousson sur l'Afrique centrale, on montre le rôle clé qui a toujours été joué par les variations des Températures Marines de Surface. Enfin, on montre que cette vaste perturbation qui est survenue avec des conditions régionales et globales relativement "chaudes" peut être un "analogue" de ce qui pourrait se produire en Afrique centrale au cours de la phase de "Réchauffement Global" qui est prédite pour le XXIème siècle.
 
Dactyladenia ndjoleensis from Ndjolé, NW Gabon, is described and illustrated.
 
Description of Sorindeia oxyandra (Anacardiaceae) from Gabon, given with an illustration. /// Description de Sorindeia oxyandra (Anacardiaceae) du Gabon, accompagnée d'une illustration.
 
Gardenia epiphytica (Rubiaceae) from the forests of Gabon and Cameroon is described and illustrated. It is the fourth record of an epiphytic species in afrotropical Rubiaceae.
 
Clerodendrum sassandrense Jongkind (Lamiaceae, Ajugoideae) from the forest of south-west Côte d'Ivoire is described and illustrated.
 
Psychotria kwewonii (Rubiaceae) from the forests of Liberia, Côte d'Ivoire and Ghana is described and illustrated, and its possible affinities discussed.
 
Annickia affinis (Exell) Versteegh & Sosef: A. leaf, lower surface, and flower; B. detail, lower leaf surface; C. floral bud with bracteoles (Le Testu 1783); D. torus; E. petal; F. stamen front and back view; G. carpel and section of carpel; H. fruit (Letouzey 5412).-Annickia ambigua (Robyns & Ghesq.) Setten & Maas: I. leaf, lower surface; J. detail, lower leaf surface; K. floral bud; L. fruit (Sargos 193). © Publications Scientifiques de Muséum national d'Histoire naturelle, Paris, reproduced with permission from Le Thomas (1969: 311).
Annickia lebrunii (Robyns & Ghesq.) Setten & Maas: A. leaf, lower surface; B. detail, lower leaf surface (Leonard 1595). – Annickia chlorantha (Oliv.) Setten & Maas: C. leaf, upper surface; D. detail, lower leaf surface; E. carpel; F. stamen (Okafor FHI 66039). Drawing by Mrs. W. Wessel-Brand.  
Annickia kummerae (Engl. & Diels) Setten & Maas: A. flowering branch (Greenway 921); B. floral bud (from Engler 1901). C. cross section of flower (sepals removed); D. petal; E. stamen, front view; F. stamen, side view; G. carpel (Greenway 921). H. fruit; I. seed; J. transverse section of seed; K longitudinal section of seed (Kummer 44). Drawing by Pat Halliday, reproduced with permission from Verdcourt (1971: 73).
Annickia le-testui (Le Thomas) Setten & Maas: A. flowering branch, leaves, lower surface; B. detail, lower leaf surface; C. stellate hair through microscope; D. floral bud; E. petal; F. stamen; G. carpel, section of carpel; H. diagram of flower (Le Testu 8432).-Annickia pilosa (Exell) Setten & Maas: I. leaf, lower surface, and floral bud; J. detail, lower leaf surface; K. flower; L. petal; M. stamen; N. carpel, section of carpel (CTFT s.n.). © Publications Scientifiques de Muséum national d'Histoire naturelle, Paris, reproduced with permission from Le Thomas (1969: 307).
Annickia polycarpa (DC.) Setten & Maas; A. flowering branch; B. detail of leaf, lower surface; C. flower; D. petal; E. carpel; F. stamen; G. fruit (de Koning 1021, de Koning 6415). Drawing by Mrs. W. Wessel-Brand.  
complete revision, including a key to the species, drawings and distribution maps, of the tropical African Annonaceae genus Annickia (= Enantia Oliv., non Falc.) is presented. The exact phylogenetic position of this genus within the family has long been, and in fact still is, unclear. The status of four species, A. ambigua, A. atrocyanescens, A. kwiluensis and A. olivacea, has been elucidated. All four refer to the same species: A. ambigua. One new combination, A. affinis (Exell) Versteegh & Sosef, was needed. The well-known A. chlorantha, the bark of which is reputed for its anti-malarial activity, appears to be a rare species confined to southern Nigeria and Cameroon. It has been frequently confused with the more widespread A. affinis. The genus Annickia now comprises eight species, several of which show interesting distribution patterns.
 
Strombosia retivenia S.Moore (Olacaceae) from Nigeria, hitherto treated as a synonym of Diogoa zenkeri (Engl.) Exell & Mendonça (Olacaceae), proved to represent a distinct species of that genus. The combination Diogoa retivenia is made. As a consequence Diogoa is no longer monospecific. The two Guineo-Congolese species are geographically separated. Their distributions are mapped. The wide gap in the distribution of Diogoa zenkeri is discussed. Diogoa retivenia, as well as the main distinguishing features of D. zenkeri, are illustrated. A key to the two species is provided. D. zenkeri is lectotypified.
 
A monograph of Chilocarpus, a genus counting thirteen species of the Apocynaceae-Plumerioideae-Chilocarpeae restricted to tropical Asia, is given. Two keys to the species are presented, one for flowering and one for fruiting material. All species are described in detail and maps depict their geographical distribution. The study is based on herbarium specimens; for only five species living material was at disposal. /// Une monographie de Chilocarpus, un genre de treize espèces restreint à l'Asie tropicale, est présentée. Deux clés des espèces sont données, une pour les échantillons florifères et une pour du marériel en fruit. Toutes les espèces sont décrites en détail et des cartes de répartition sont produites. L'étude est basée surtout sur matériel d'herbier, seulement cinq espèces étant disponibles à l'état vivant.
 
Monograph of Melodinus, the only genus of the Melodineae (Apocynaceae, Plumerioideae, Carisseae), containing 19 species and restricted to tropical Asia and Australia. Five keys to the species are presented, one for the entire genus, one for the species represented in China, one for the species present in the countries covered by Flora Malesiana, one for the species known from New Caledonia and one for those from Australia. /// Monographie de Melodinus, le seul genre des Melodineae (Apocynaceae, Plumerioideae, Carisseae). Il comprend 19 espèces et est limité à l'Asie et à l'Australie. Cinq clés des espèces sont presentées, une pour le genre entier, une pour les espèces représentées en Chine, une pour les espèces trouvées dans les pays couverts par la Flora Malesiana, une pour la Nouvelle-Calédonie et une pour l'Australie.
 
Leuconotis Jack, a genus counting five species, is restricted to tropical Asia. A key to the species is presented. All five species, two of which are new to science are described in detail and distribution maps are given for the most wide-spread species. Most of the names known from literature turned out to be synonyms of L. anceps. The study is based mainly on herbarium material as only a few specimens have been seen as living plants. Several type specimens of names, putative synonyms of L. anceps, were sterile, and some were lost. For L. anceps a neotype is selected, as no type material could be traced. /// Leuconotis, un genre de cinq espèces est restreint à l'Asie tropicale. Une clé des espèces est présentée. Les cinq espèces, parmi lesquelles deux sont nouvelles pour la science, sont décrites en détail; des cartes de répartition sont ajoutées pour les deux espèces à large distribution. La plupart des noms connus de la littérature apparaissent être des synonymes de L. anceps. L'étude est fondée surtout sur du matériel de l'herbier, parce que peu des échantillons ont été vus comme plantes vivantes. Plusieurs échantillons types de noms, probablement synonymes de L. anceps, sont steriles, et quelques uns sont perdus. Un néotype a été choisi pour L. anceps, parce que son type ne pouvait pas être retrouvé.
 
Phytochorological spectra for (A) all species (358 species) in Pongara National Park, (B) forest species (232 species), and (C) savannah species (92 species). 
Phytochorological spectra for the Guineo-Congolian species from the forest vegetation in Pongara National Park (191 species). 
This first checklist of the vascular plants of Pongara National Park in coastal Gabon comprises 385 taxa. The checklist is based on a botanical inventory carried out in 2006-2007 and on existing collections from the Park. Information on ecology and chorology is given for each species. Ninety-five species were collected in the littoral savannah, half of which belonged to Poaceae, Cyperaceae and Orchidaceae, and 356 species in the littoral forest, mainly Rubiaceae (33), Orchidaceae (15) and Euphorbiaceae (12). The savannah has a much higher percentage of widespread species than the forest. Eighty-three species are endemic to Lower Guinea, nine of which are endemic or near endemic to Gabon.
 
Leptoderris sassandrensis from the forests of West Africa (Upper Guinea), is described and illustrated. The differences between the new species and Leptoderris fasciculata are explained.
 
The taxonomy of Millettia Wight & Arn. is in need of revision. For Africa, sect. Efulgentes and Opacae are under review. The main distinction between both sections is the shininess of the leaves. In line with the treatments of Asian species the African material has been described and prepared for phylogenetic analysis. A brief overview with preliminary data is given. Full details are intended to be published in the forthcoming revision.
 
In this study the possibility of rainforest outside the postulated refuge areas is explored by assessing the presence of rainforest Caesalpinioideae in Lope forest savannah mosaic in Gabon. In this dry area twenty-six tree species of this subfamily were located. Their physiological ability to cope with drought stress and their impossible migration from the nearest postulated refuge area strongly suggests that these species remained in the Lope area during the last ice age. Extrapola- ting this observation and incorporating all refuge indicator species outside the postulated refuge area, supports the idea that small fragments of forest persisted during the last ice age acting as
 
In 1903 and 1904, Georges Bronckart, a Belgian living in Indochina, corresponded with the orchid specialist Alfred Cogniaux. Five of his letters, in French, conserved in BR, are reproduced here. They deal with specimens send from Annam (Vietnam) to Belgium, ask for information on their identification, and make proposals for trade. The scanty biographical information on this orchid amateur is reviewed. Some Bronckart material became important for horticulture and hybridizing, e.g. Dendrobium bronckartii De Wild.
 
A short biographical sketch introduces the list of the 427 publications of André Lawalrée, honorary Head of the Department Vascular Plants (Spermatophyta-Pteridophyta) of the National Botanic Garden of Belgium. His works deal with systematics and floristics of a wide array of vascular plant groups (inter alia ferns and composites) from Europe and tropical Africa, botanical illustration, and history of botany. A list of the twelve taxa that commemorate André Lawalrée is given.
 
From the early sixties onwards, the fragility and exceptional biological richness of the forest ecosystem of Aubeville, situated in the Niari valley, has been acknowledged. The region figures on a list of critical sites that urgently need to be conserved. In spite of this status, the forest, of which the flora was very imperfectly known, has suffered from industrial wood exploitation (1953–1988), traditional exploitation of goods and services by locals, and finally, since 1988, from strong human pressure due to slash and burn agriculture. The present study, though incomplete, is the very first one to inventory the floristic diversity of Aubeville forest. As a result, 135 species are identified; they belong to 122 genera and 60 families. They are associated with crop plants and introduced plants. This flora marks three habitats that correspond to microclimatic variations of the mesoclimat. French L'écosystème forestier aubevillois, dont la fragilité physique et l'exceptionnelle valeur de la biodiversité, au sein de la vallée du Niari sont reconnues dès le début des années soixante est inscrit sur la liste des sites critiques à protéger prioritairement. En dépit de ce statut, cette forêt, qui n'a pas livré les secrets de sa flore, a connu successivement et/ou concomitamment, l'exploitation industrielle de bois d'œuvre (1953–1988), l'exploitation artisanale des biens et des services, par les populations locales, et enfin, depuis 1988, elle connaît une forte pression anthropique due à la quête de nouvelles terres propices à l'agriculture itinérante sur brûlis. Cette étude, quoique partielle, est la toute première qui marque un intérêt à l'inventaire et à la connaissance de sa biodiversité floristique. Au stade actuel des connaissances, 135 espèces sont identifiées pour 60 familles et 122 genres. Elles sont associées aux plantes cultivées et aux spontanées. Cette flore marque trois habitats tenant à des variations microclimatiques au sein de ce mésoclimat.
 
A new species of Bertiera (Rubiaceae) from Cameroon and Gabon, Bertiera heterophylla Nguembou & Sonké, is described and illustrated. This new species belongs to the subgenus Bertiera and appears to be closely related to Bertiera bicarpellata. Bertiera heterophylla differs from B. bicarpellata in having lateral branches with terminal inflorescences while on the main stem, the inflorescences are axillary.
 
Top-cited authors
Elmar Robbrecht
  • Meise Botanic Garden
Luc Ector
  • Luxembourg Institute of Science and Technology (LIST)
Rainer W Bussmann
  • Staatliches Museum für Naturkunde Karlsruhe
Brice Sinsin
  • University of Abomey-Calavi
Erik F Smets
  • Naturalis Biodiversity Center