Four new species of Chlorophytum (Anthericaceae) from tropical Africa

Four new species of Chlorophyrum from tropical Africa are described: C. graniticola from Zimbabwe, C. minor and C. perfoliatum from Zambia, and C. velutirzum from Malawi, Tanzania, Zambia and Zaire.     

New combinations of African species in the genus Chlorophytum (Anthericaceae)

The generic delimitation of the genus Chlorophytum Ker-Gawl emend. Nordal is discussed and outlined, especially in relation to the genus Anthericum L. Two new names and 39 new combinations for African taxa have been necessitated by the emendated delimitation of the genus.     

Reproductive biology in diploid Anthericum ramosum and tetraploid A. liliago (Anthericaceae)

Polyploidy is often thought to be associated with asexual reproduction, self-compatibility and self-pollination. Polyploids are also often regarded as being less sensitive than diploids to the negative effects of inbreeding. The reproductive biology of two lilioid species, the diploid Anthericum ramosum and the tetraploid A. liliago , was compared in a series of greenhouse and field experiments. Pollination experiments were carried out to study agamospermy (seed set without fertilization), self-compatibility and early inbreeding depression for both species. Tetraploid A. liliago showed no greater ability to self-pollinate than diploid A. ramosum and neither of the species showed agamospermy. Both species were self-compatible, but levels of fruit and seed set were lower after self-fertilization than after cross-fertilization in A. ramosum ( P <0.001). No reduction in fecundity after self-fertilization was observed in A. liliago . Fruit set in natural populations of A. ramosum increased significantly ( P <0.001) after emasculation (which excluded the possibility of autodeposition of pollen within flowers). In contrast, emasculation of flowers reduced the fruit set within natural populations of A. liliago ( P <0.05). The reproductive biology of diploid A. ramosum and tetraploid A. liliago is discussed in the context of polyploidization and the reduced fruit and seed set after self-fertilization in A. ramosum is discussed in terms of early inbreeding depression.     

Genetic variation in Scandinavian Anthericum liliago (Anthericaceae): allopolyploidy, hybridization and immigration history

 We investigated patterns of isozyme variation and the hierarchic structure of genetic diversity in 25 Scandinavian populations of the lilioid herb, Anthericum liliago. Isozyme data suggest that tetraploid A. liliago has an allopolyploid origin and that A. ramosum may be one of its diploid progenitors. Two populations contained known or suspected hybrids between A. liliago and A. ramosum. Isozymes show that one population from S Sweden contains both triploid (hybrid) and tetraploid individuals whereas a putatively hybrid Danish population represents diploid A. liliago. There is an overall northward and eastward decline in allelic richness in the tetraploid populations, with the highest numbers of alleles in Denmark and SW Sweden. This pattern is consistent with a progressive loss of allelic variation during the species' postglacial colonization of Scandinavia. The between-population component of genetic diversity is 4% (compared with 12% in diploid A. ramosum), the between-region diversity component is 7% and 89% of the total diversity is stored within populations. Received March 13, 2002; accepted September 24, 2002 Published online: December 11, 2002     

A new species of Acacia (Leguminosae) from the Horn of Africa

Acacia cernua , sp. nov., is described from open Acacia-Commiphora bushland on the foothills of the north-facing limestone escarpment running along the coast of northern Somalia. The new species is obviously closely related to the widespread A. etbaica that is common on this escarpment, but at considerably higher altitudes. A. cernua differs from A. etbaica in, for example, its smooth, ash grey to white bark, and in its slender, hanging terminal branches with a glaucous foliage.     

Four new species of Sida (Malvaceae) from the Horn of Africa

Sida floccosa , sp. nov., from eastern Ethiopia and north-western Somalia, S. ogadensis , sp. nov., from eastern Ethiopia and central Somalia, 5. calliantha , sp. nov., from coastal dunes in southern Somalia, and S. longipedicellata sp. nov., from coastal dunes and sandy plains in central and south-central Somalia, are described and illustrated.     

Seven new species of Pavonia (Malvaceae) from the Horn of Africa

Pavonia friisii , sp. nov., from south-eastern Ethiopia and south-central and southern Somalia, P. nigrescens , sp. nov., from south-central and southern Somalia, P. matteiana , sp. nov., from south-central Somalia, P. longipilosa , sp. nov., from eastern Ethiopia, P. rotundifolia , sp. nov., from eastern Ethiopia and northern and central Somalia, P. marginata , sp. nov., from central Somalia, and P. paucibracteata , sp. nov., from central Somalia, are described and illustrated.     

Synopsis of Canotia (Celastraceae) including a new species from the Chihuahuan desert

Canotia, a genus of holacanthoid shrubs of southwestern United States and northern Mexico, is redescribed, and reasons are advanced for retaining it in the family Celastraceae. Two species are recognized, includingC. wendtii sp. nov. from Chihuahua.     

New taxa of Chlorophytum (Anthericaceae) from southern tropical Africa with notes on their sister group relationships

Six new taxa of Chlorophytum (five from Zambia and one from Malawi) are described, namely C. bulbinifolium Hoell & Nordal, C. zambiense Bjorå & Nordal, C. chelindaensis Kativu & Nordal, C. clarae Bjorå & Nordal, C. blepharophyllum Schweinf. ex Baker ssp. rubropygmaeum Bjorå & Nordal, and C. blepharophyllum Schweinf. ex Baker ssp. pendulum Hoell & Nordal. The sister group relationships of the new taxa were studied by cladistic analyses of nuclear and chloroplast DNA sequences. Chlorophytum bulbinifolium has an isolated position in the cladogram. It is morphologically closest to C. subpetiolatum (Baker) Kativu, but differs by its narrow succulent leaves and smaller flowers. Chlorophytum zambiense is nested with C. andongense Baker, C. macrosporum Baker, and C. viridescens Engl., but differs by being more slender and by having ebracteate peduncles and smaller flowers. Chlorophytum chelindaensis belongs in the C. colubrinum Engl. complex, differing from C. colubrinum by its small habit and hairy leaves. Chlorophytum clarae is in a clade with C. pusillum Schweinf. ex Baker and C. pauper Poelln. It is morphologically closest to C. macrophyllum Asch., but has globose capsules and smaller irregularly folded seeds.  © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society , 2008, 157 , 223–238.     

A new species and new records of Helianthemum (Cistaceae) from the Horn of Africa region

Helianthemum speciosum , sp. nov., from gypsum outcrops in north-eastern Somalia, is described and illustrated. H. stipulatum is recorded for the first time from Somalia and Yemen.     

Genetic structure detected in a small population of the endangered plant Anthericum liliago (Anthericaceae) by RAPD analysis

We report results showing that the RAPD technique is a powerful method for detailed genetic analysis of a small natural population of the endangered plant species Anthericum liliago L. (Anthericaceae). This population grows on silicate grasslands in central Germany. We investigated all 127 ramets found in the population area. Within the population area, restricted to ca 45 m², we visually identified three subpopulations. Analysis of 54 RAPD markers revealed a relatively low level of genetic polymorphism (34.6%) and a pronounced subpopulation structure within the studied population. Our results show a significant (p<0.001, r=0.423) correlation between genetic and spatial distances within this population which may be a result of restricted pollen and seed dispersal and of a high selfing rate. In the studied population the ant species Myrmica sabuleti (Meinhart) is probably the main pollinator for A. liliago. These ants have a relatively small radius of movement and therefore pollen transfer mediated by ants probably restricts gene flow in the A. liliago population. We suggest that the time of flowering and the distance between individual plants play an important role in successful pollination and seed production of the investigated A. liliago population.     

Trachyandra triquetra (Asphodelaceae), a new species from the Horn of Africa

The new species Trachyandra triquetra , from shady limestone rocks in north-eastem Somalia, is described and illustrated. This apparently narrow endemic is the only member of this mainly South African genus in eastern and north-eastem tropical Africa except for the widespread T. saltii .     

Diceratella alata (Cruciferae), a new species from the Horn of Africa

Diceratella alata (Cruciferae, Matthioleae) is described and illustrated. It is only known from a small area in Central Somalia and SE Ethiopia. By its prominently winged siliquae it is extreme within the genus.     

Habitat fragmentation and the structure of genetic diversity within disjunct isolates of Anthericum ramosum L. (Anthericaceae) in Scandinavia

The lilioid herb, Anthericum ramosum , occurs in four geographically-isolated regions (Sjælland, Skåne, Öland and Gotland) in Denmark and southern Sweden. We investigated allozyme variation at nine polymorphic loci in A. ramosum from 16 sites (33 populations) in the four regions. There was no clear overall geographic pattern of differentiation between the regions, but the southernmost Gotland and the Öland populations had similar allele frequencies, suggesting that they have had a common history. The total genetic diversity (H_10t) was 0.458 and the between-region, site- and population components of diversity accounted, respectively, for 13%, 10% and 2% of the total diversity. The species is restricted to grassland habitats. Such habitats have become increasingly rare in the Sjælland and Skåne regions, where A. ramosum now has a highly fragmented distribution. Within three of the regions (Sjælland, Skane and Öland) there was a negative relationship between the extent of grassland habitat and the between-site components of genetic diversity. Öland, with its extensive grassland habitats and low levels of population disjunction, showed litde allelic differentiation between sites and the lowest between-site component of diversity (3%), suggesting that there is (or has been) extensive gene flow between sites. The between-site components of diversity were higher within Skåne (7%) and Sjaelland (12%). The high within-region G_ST (25%) for the fourth region, Gotland, cannot be explained in terms of recent habitat disjunction but is, instead, interpreted in terms of the restricted distribution of limestone bedrock on Gotland and the fact that die southern and northern Godand populations appear to have had different origins.     

A phenetic analysis and revision of Guineo-Congolean rain forest taxa of Chlorophytum (Anthericaceae)

The taxonomy of rain forest species of the genus Chlorophytum in central and west Africa has to date been difficult to resolve. Plants collected in the Guineo-Congolean plant geographical region deposited in several herbaria formed the basis for a morphometric analysis using Principal Component Analyses and including 16 characters. In total, 166 individuals were included from 461 herbarium collections, from which 57 seeds were scanned to investigate the surface structures. Eight species are recognized, including one with three subspecies and another with three varieties. Four new combinations are proposed ( Chlorophytum comosum (Thunb.) Jacques var. bipindense (Engl. & K. Krause) A.D. Poulsen & Nordal, C. comosum (Thunb.) Jacques var. sparsiflorum (Baker) A.D. Poulsen & Nordal, C. lancifolium Baker ssp. cordatum (Engl.) A.D. Poulsen & Nordal, and C. lancifolium Baker ssp. togoense (Engl.) A.D. Poulsen & Nordal), ten new synonyms are introduced and three lectotypes are designated.  © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society , 2005, 148 , 1–20.     

Three new species of Chascanum (Verbenaceae) and notes on the genus in the Horn of Africa region

The new species Chascanum mixtum, from evergreen bushland and rocky slopes in north-western Somalia, C. elburense. from deciduous bushland mainly on sand in central Somalia, and C. glandulosum, from Acacia-Commiphora bushland on sandy soil in north-western Somalia, are described and illustrated. C. sessilifolium (Vatke) Moldenke is recircumscribed and neotypified with a specimen from the original type locality, and C. obovatum Sebsebe ssp. glaucum Sebsebe is placed in the synonymy of C. gillettli Moldenke.