Xander M. van der Burgt

Royal Botanic Gardens, Kew · Herbarium

Virectaria (Sabiceeae-Cinchonoideae-Rubiaceae), is a morphologically isolated genus of tropical African herbs or subshrubs, occurring from Senegal to Tanzania. Virectaria stellata, a new species from Guinea, is published. It is a perennial herb, with stems becoming creeping and rooting, to 60 cm long. Virectaria stellata has stellate hairs, recorde...

Virectaria is a morphologically isolated genus of tropical African herbs or subshrubs, occurring from Senegal to Tanzania. Virectaria stellata, a new species from Guinea, is published. It is a perennial herb, with stems becoming creeping and rooting, to 60 cm long. Virectaria stellata has stellate hairs, recorded here for the first time in the fami...

Ancistrocladus pachyrrhachis (Ancistrocladaceae), described in 1950, is resurrected and compared with A. barteri, the species with which it was synonymised in 2005. The fruits of Ancistrocladus barteri and A. pachyrrhachis are described and illustrated here for the first time, and a full description of the species is provided, as is a key to the th...

Premise of research. Several morphotypes of well-preserved legume leaflet compressions are known from the early Miocene Mush plant assemblages from the northwestern plateau of Ethiopia. One of these morphotypes represents a member of the Amherstieae tribe (subfamily Detarioideae) and is prevalent in the assemblage. Morphological and epidermal micro...

Tephrosia kindiana , a new plant species from Guinea, is described and illustrated. It is a shrub 90 – 120 cm tall, multi-stemmed from the base. The leaves have 5 – 13 oblanceolate leaflets; the inflorescence consists of solitary flowers in the leaf axils, or 2 – 3-flowered fascicles; the flowers are orange and 24 – 26 mm long. The species occurs i...

The Checklist of the Vascular Plants of the Republic of Guinea (CVPRG) is a specimen-based, expert-validated knowledge product, which provides a concise synthesis and overview of current knowledge on 3901 vascular plant species documented from Guinea (Conakry), West Africa, including their accepted names and synonyms, as well as their distribution...

Many tropical wet forests are species-rich and have relatively even species frequency distributions. But, dominance by a single canopy species can also occur in tropical wet climates and can remain stable for centuries. These are uncommon globally, with the African wet tropics supporting more such communities than the Neotropics or Southeast Asia....

We describe two range-restricted new species to science from the genus Impatiens (Balsaminaceae), both threatened, from lowland of the Cross-Sanaga Interval of western Cameroon. The first, Impatiens banen, appears to be restricted to an open seepage microhabitat on granitic inselbergs in the lowland-submontane forest zone of the Ebo Forest in Litto...

Conservation action plans need to be devised and implemented if we are to reduce the extinction risk faced by globally threatened plants. However, most plant species categorized as threatened globally on the IUCN Red List lack conservation action plans. In West Africa, Guinea is one of the most diverse countries in terms of botanical species. In to...

The tribe Sonerileae in tropical Africa and Madagascar is a morphologically diverse lineage that consists of 239 species in 10 genera. In this study, we present the first in‐depth phylogenetic analysis of African Sonerileae to test monophyly of the currently recognised genera. Phylogenetic analyses were performed using sequence data from two nuclea...

Abstract: Benna is a new monospecific genus in the Melastomataceae, from the Benna Plateau in Forécariah Prefecture in Guinea, West Africa. Molecular sequence data show the genus Benna is nested within the tribe Sonerileae but clearly unrelated to the other African Sonerileae genera. The genus is weakly supported as sister to the South American Son...

Background The Ebo Forest area is a highly threatened centre of diversity in the Littoral Region of Cameroon, globally important for conservation with many threatened species including 68 threatened species of plant, yet not formally protected. The tropical African evergreen forest tree genus Uvariopsis Engl. & Diels (Annonaceae) is characterised b...

Background and aims – We studied a cluster of trees in the Leguminosae subfamily Detarioideae, to: (1) determine the size, structure, and tree species composition of this cluster; (2) map the size, shape, and structure of groups of individual Detarioideae tree species in the cluster.Location – Lowland rain forest in southern Korup National Park, in...

Four species of Rinorea are described as new to science; all four species are endemic to evergreen rain forest in Cameroon. Rinorea villiersii Achound. and R. amietii Achound are placed in Rinorea [unranked] Crassiflorae M.Brandt, while, R. dewildei Achound. and R. faurei Achound. fall in Rinorea [unranked] Dentatae Engl. The first species appears...

A new species of rheophytic grass from Benna Plateau in Guinea. The plateau is a species-rich area and is designated as a Tropical Important Plant Area.

Four species of Rinorea are described as new to science; all four species are endemic to evergreen rain forest in Cameroon. Rinorea villiersii Achound., and Rinorea amietii Achound. are placed in Sect. Crassiflorae Wahlert, while Rinorea dewildei Achound. and Rinorea faurei Achound. fall in Rinorea section Dentatae (Engl.) Wahlert. The first specie...

A new species to science of evergreen forest tree, Uvariopsis ebo (Annonaceae) is described, illustrated, mapped, and compared morphologically with the other cauliflorous species of the genus. Restricted so far to a single site in evergreen lowland forest in the Ebo Forest, Yabassi, Littoral Region, Cameroon, this species is Critically Endangered u...

The genus Cailliella includes a single species, C. praerupticola, restricted to a sandstone plateau region in Coyah, Dubreka, Forécariah and Kindia Préfectures, Guinea, West Africa. Until its rediscovery in 2016, this species was known only by the type gathering made in 1937. We provide an emended description, photographs of living material, locali...

This is the first revision in more than 100 years of the African genus Pseudohydrosme , formerly considered endemic to Gabon. Closely related to Anchomanes , Pseudohydrosme is distinct from Anchomanes because of its 2-3-locular ovary (vs. unilocular), peduncle concealed by cataphylls at anthesis and far shorter than the spathe (vs. exposed, far exc...

This is the first revision in nearly 130 years of the African genus Pseudohydrosme , formerly considered endemic to Gabon. Sister to Anchomanes, Pseudohydrosme is distinct from Anchomanes because of its 2–3-locular ovary (not unilocular), peduncle concealed by cataphylls at anthesis and far shorter than the spathe (not exposed, far exceeding the sp...

Trichanthecium tenerium Xanthos, a new species from Guinea-Conakry, is described and illustrated. Trichanthecium tenerium is at present known only from two uninhabited sandstone table mountains in the Kounounkan Massif, Forécariah Prefecture. The species is assessed under the IUCN category Endangered. A key to the annual species of Trichanthecium i...

To achieve conservation success, we need to support the recovery of threatened species. Yet, <5% of plant species listed as threatened on the IUCN Red List have Species Conservation Action Plans (CAPs). If we are to move from a Red List to a Green List for threatened plant species, CAPs need to be devised and implemented. Guinea is one of the most...

Conservation Action Plan for Eriosema triformum, endemic species of Guinea

Ternstroemia guineensis is described from a sandstone table mountain at Kounounkan, possibly the last in the Fouta Djallon (Guinea Highlands) to remain largely unimpacted by humans and to have mainly intact natural habitats. It occurs about 2400 km westward of the nearest existing record (Nigeria) of the genus in Africa. It is confined to cloud (su...

Gladiolus mariae Burgt (Iridaceae), a new species from Guinea, West Africa, is described and illustrated. The new species is placed in Gladiolus sect. Decorati Goldblatt and compared with the nine species already known from that section. Flowering plants stand 28 - 160 cm high with 1 - 6 bright orange flowers, opening one at a time. The ecology of...

Conservation Action Plan for Cailliella praerupticola, an endemic Melastomataceae species from Guinea.

Conservation Action Plan for Talbotiella cheekii, an endemic legume tree from Guinea.

Talbotiella cheekii Burgt, a new tree species from Guinea, is described and illustrated. It is a tree to 24 m high, with a stem diameter to 83 cm, and occurs in forest dominated by tree species of the Leguminosae subfamily Detarioideae, on rocky stream banks and rocky hill slopes, at an altitude of 100 – 600 m. It is estimated that 1600 – 2400 matu...

Ledermanniella yiben Cheek is described from the Seli (Rokel) river bed at a single rapid to be flooded by the proposed Yiben hydroelectric dam and reservoir in Sierra Leone. It is assessed as Critically Endangered using the IUCN categories and criteria. The species appears to be unique among African Podostemaceae in bearing dimorphic shoots having...

Background: Understanding the patterns of biodiversity distribution and what influences them is a fundamental pre-requisite for effective conservation and sustainable utilisation of biodiversity. Such knowledge is increasingly urgent as biodiversity responds to the ongoing effects of global climate change. Nowhere is this more acute than in species...

Abstract Six new species of Inversodicraea (I. feika from Sierra Leone, I. liberia from Liberia, and I. ebo, I. eladii, I. tchoutoi, and I. xanderi from Cameroon) are described as new to science in the context of a synoptic revision of this African genus, now comprising 30 species, including I. cussetiana comb. nov., newly transferred from Macropod...

Five new species of Englerophytum K. Krause (Sapotaceae) are described: Englerophytum paludosum L. Gaut., Burgt & O. Lachenaud, Englerophytum gigantifolium O. Lachenaud & L. Gaut., Englerophytum libenii O. Lachenaud & L. Gaut., Englerophytum sylverianum Kenfack & L. Gaut., and Englerophytum ferrugineum L. Gaut. & O. Lachenaud. All five species are...

The tropical vegetation of Africa is characterized by high levels of species diversity but is undergoing important shifts in response to ongoing climate change and increasing anthropogenic pressures. Although our knowledge of plant species distribution patterns in the African tropics has been improving over the years, it remains limited. Here we pr...

Humans possess the unique ability for cumulative culture [1, 2]. It has been argued that hunter-gatherer's complex social structure [3-9] has facilitated the evolution of cumulative culture by allowing information exchange among large pools of individuals [10-13]. However, empirical evidence for the interaction between social structure and cultural...

Gambeya korupensis Ewango & Kenfack (Sapotaceae: Chrysophylloideae), a new rain forest tree species from the Southwest Region in Cameroon, is described and illustrated. A distribution map is provided. G. korupensis has the leaf blade below pubescent on the midribs and secondary nerves, flowers with a pedicel 0.5 – 1 mm long, and a fruit which is ov...

Two new tree species, Didelotia korupensis and Tessmannia korupensis (Leguminosae, Caesalpinioideae), are described and illustrated. Didelotia korupensis is the 12th species in the genus. It is an understory tree to 15 m tall with an often leaning stem to 30(–53) cm diam. Didelotia korupensis is only known from an area of c. 4 km2 in and near the p...

The tropical vegetation of Africa is characterized by high levels of species diversity but is undergoing important shifts in response to ongoing climate change and increasing anthropogenic pressures. Although our knowledge of plant species distribution patterns in the African tropics has been improving over the years, it remains limited. Here we pr...

The Gilbertiodendron ogoouense species complex consists of 14 tree species. Eight species are here newly described and one is here reinstated: G. bambolense Burgt; G. breteleri Burgt; G. ebo Burgt & Mackinder; G. ecoukense (Pellegr.) Burgt; G. maximum Burgt & Wieringa; G. minkebense Burgt & Estrella; G. quinquejugum Burgt; G. scutatum Wieringa & Es...

Premise of research: Gilbertiodendron is a genus endemic to Africa with ∼30 species made up of trees of primary dry-land, riverine, and gallery forests. Recently, the west and central African monotypic genus Pellegriniodendron was merged into Gilbertiodendron. Gilbertiodendron is one of 17 genera that form the exclusively African Berlinia clade, an...

The tree species Cryptosepalum korupense Burgt, sp. nov. (Leguminosae: Caesalpinioideae) is described and illustrated. Cryptosepalum korupense, sp. nov. is related to C. staudtii Harms. Cryptosepalum korupense, sp. nov. has (10-)14-21(-26) pairs of leaflets; C. staudtii has 10-14(-16) pairs of leaflets. The placement of the midvein of the small, em...

The large-crowned emergent tree Microberlinia bisulcata dominates rain forest groves at Korup National Park, Cameroon, along with two codominants, Tetraberlinia bifoliolata and T. korupensis. M. bisulcata has a pronounced modal size frequency distribution around ∼110 cm stem diameter: its recruitment potential is very poor. It is a long-lived light...

A photograph taken in the field of the amphicarpous Schoenoplectiella oxyjulos (S. S. Hooper) Lye provided evidence for the first time of a very close association between the ‘basal’ female floret and upper bisexual spikelet of an inflorescence. Dissections and observations show this affects development within the bisexual floret.

Two new species of Eriocaulon (Eriocaulaceae) from the Sula Mountains in northern Sierra Leone are described and illustrated. Eriocaulon petraeum S. M. Phillips & Burgt is a perennial herb forming dense clumps on bedrock and boulders in the riverbed of the Tonkolili River in the Sula Mountains. Eriocaulon sulanum S. M. Phillips & Burgt is a perenni...

Eriosema triformum Burgt (Leguminosae: Papilionoideae), a new species from Guinea in West Africa, is described and illustrated. E. triformum is a pyrophytic herb with unifoliolate leaves, from submontane grassland at 1,250 – 1,600 m altitude. The species exhibits three phases during the year: a dormant phase during which only the underground tuber...

A revision of the genus Talbotiella Baker f. (Caesalpinioideae: Leguminosae) is presented. Four species from Cameroon are described as new and a species of Hymenostegia, also from Cameroon, is transferred to Talbotiella bringing the number of species in Talbotiella to eight: T. bakossiensis Cheek, T. batesii Baker f., T. breteleri (Aubrév.) Mackind...

Gilbertiodendron tonkolili Burgt & Estrella sp. nov. (LeguminosaeCaesalpinioideae) is described and illustrated. The new species is endemic to a small area in central Sierra Leone. Gilbertiodendron tonkolili is characterised by leaves bearing 46 pairs of leaflets; stipules comprising a lower auriculate and an upper linear part, creamwhite coloured...

The tree species Gilbertiodendron newberyi Burgt (Leguminosae: Caesalpinioideae) is described and illustrated. The new species is related to G. ogoouense (Pellegr.) J. Léonard s. s. Trees of G. newberyi can grow to 51 m high and 197 cm trunk diam. The new species is ectomycorrhizal, grows gregariously, and presents ballistic seed dispersal. G. newb...

Pseudovigna sulaensis R. Clark & Burgt (Leguminosae: Papilionoideae), a new species from Sierra Leone, is described and illustrated. It is a herb from submontane grassland, with annual twining stems to several metres long, sprouting from a perennial woody rootstock. The erect inflorescences have violet flowers. The new species is only known from th...

In groves of ectomycorrhizal caesalpiniaceous species in the Atlantic coastal forest of Central Africa the dominant tree Microberlinia bisulcata, which is shade-intolerant as a seedling but highly light-responding as a sapling, shows very limited regeneration. M. bisulcata saplings were mapped in an 82.5-ha plot at Korup and found to be located sig...

Background In the course of the identification work of trees in the permanent plots around the "P transect" in the southern part of Korup National Park, Cameroon, two new taxa in Magnistipula Engl. were discovered. Key results Magnistipula multinervia Burgt and Magnistipula butayei De Wild. subsp. korupensis Burgt (Chrysobalanaceae) are described a...

In groves of ectomycorrhizal caesalpiniaceous species in the Atlantic coastal forest of Central Africa the dominant tree Microberlinia bisulcata, which is shade-intolerant as a seedling but highly light-responding as a sapling, shows very limited regeneration. M. bisulcata saplings were mapped in an 82.5-ha plot at Korup and found to be located sig...

Five species of achlorophyllous heteromycotrophs, better known as saprophytes, are here reported from Guinea for the first time, raising the national total to six. They include a new species, Gymnosiphon samoritoureanus Cheek, which is described and illustrated, and assessed as Vulnerable using IUCN (2001). Key wordsachlorophyllous heteromycotroph...

An edited volume based on the proceedings of the eighteenth Association for the Taxonomic Study of the Flora of Tropical Africa Congress held in Yaoundé, Cameroon, Systematics and Conservation of African Plants includes one hundred research papers in separate sections on taxonomy, phytogeography, ethnobotany, and the conservation and sustainable us...

Lecomtedoxa plumosa Burgt (Sapotaceae), a new tree species from the southern part of Korup National Park in Cameroon, is described and illustrated. The flowers show the characteristics of the genus Lecomtedoxa: for example the staminodes are free and placed alternately to the stamens and corolla lobes. The leaves of the new species are clearly diff...

Buttressing is a trait special to tropical trees but explanations for its occurrence remain inconclusive. The two main hypotheses are that they provide structural support and/or promote nutrient acquisition. Studies of the first are common but the second has received much less attention. Architectural measurements were made on adult and juvenile tr...

The tree species Berlinia korupensis Mackinder & Burgt is described as new. The species is endemic to the southern part of Korup National Park in Cameroon. Seventeen trees have been found so far, the largest being 42 m high and having a trunk diam. of 88cm. The new species is assessed as Critically Endangered (CR D) under the criteria of IUCN. Two...

Englerodendron korupense Burgt (Fabaceae, Caesalpinioideae), a new tree spe- cies from the southern part of Korup National Park in Cameroon, is described and illustrated. Only 16 trees of this new species have been found up to the present. Th e largest of them was 36 m high and had a stem diameter of 83 cm. Th e infl orescence is a terminal pendulo...

Gluema korupensis Burgt (Sapotaceae), a new species from the southern part of Korup National Park in Cameroon, is described and illustrated. In total 176 trees ≥ 25 cm in stem diam. were found. The tree from which the holotype was collected was 42 m high and 125 cm in diam.; the largest tree was 238 cm in diam. The seeds are dispersed ballistically...

A 272-ha grove of dominant Microberlinia bisulcata (Caesalpinioideae) adult trees [greater-than-or-equal]50 cm stem diameter was mapped in its entirety in the southern part of Korup National Park, Cameroon. The approach used an earlier-established 82.5-ha permanent plot with a new surrounding 50-m grid of transect lines. Tree diameters were availab...

The growth rings of Pinus occidentalis Swartz trees in La Celestina, Dominican Republic, show between-tree uniformity. With difficulty, two mean time series were made from ring widths of 1) all visible, including intra-annual, rings and 2) groups of rings that were hypothesized to be annual. Both were compared with a 63-year range of rainfall data....