The taxonomy of perennial Sesuvium species in Africa has been poorly investigated until now. Previously five perennial species of Sesuvium were recognised in Africa (S. congense, S. crithmoides, S. mesembryanthemoides, S. portulacastrum, and S. sesuvioides). Based on the differing number of stamens, S. ayresii is accepted here as being distinct from S. portulacastrum. Field observations in Angola also led the authors to conclude that S. crystallinum and S. mesembryanthemoides are conspecific with S. crithmoides. A new subspecies, Sesuvium portulacastrum subsp. persoonii, is described from West Africa (Cape Verde, Gambia, Guinea-Bissau, Mauritania, Senegal). The molecular phylogeny indicates the position of S. portulacastrum subsp. persoonii within the “American lineage” as a part of the Sesuvium portulacastrum complex which needs further studies. A diagnostic key and taxonomic notes are provided for the six perennial species of Sesuvium found in Africa and recognised by the authors (S. ayresii, S. congense, S. crithmoides, S. portulacastrum subsp. portulacastrum, S. portulacastrum subsp. persoonii, S. verrucosum and the facultatively short-lived S. sesuvioides). The distribution of S. crithmoides, previously considered to be endemic to Angola, is now confirmed for the seashores of Republic of Congo and DR Congo. The American species S. verrucosum is reported for the first time for Africa (the Macaronesian islands: Cape Verde and the Canaries). It is locally naturalised in Gran Canaria, being a potentially invasive species. These findings as well as new records of S. verrucosum from Asia and the Pacific Islands confirm its proneness to transcontinental introduction. Lectotypes of S. brevifolium, S. crithmoides, S. crystallinum and S. mesembryanthemoides are selected. The seed micromorphology and anatomy of the perennial African species is studied. Compared to the seeds of some annual African Sesuvium investigated earlier, those of perennial species are smooth or slightly alveolate. The aril is one-layered and parenchymatous in all species and usually tightly covers the seed. The aril detachments from the seed coat that form a white stripe near the cotyledon area easily distinguish S. verrucosum from other species under study.

The main objective of our study is to determine whether regeneration of Pinus pinea (an exotic species) is spreading within a Pinus canariensis (native species) stand. The study area is located in the Natural Park of Tamadaba, 1400 m asl., in the NW of Gran Canaria Island (Canary Islands). Stems and regeneration of P. canariensis and P. pinea were mapped in five randomly selected plots where both species were planted together around 45 years ago. Densities and basal areas of both species were also recorded. P. canariensis demonstrated a greater ability to disperse than P. pinea. The two species showed different spatial patterns, with P. pinea tending toward a more aggregate spatial distribution of individuals than P. canariensis. Bivariate spatial relationships showed no difference from a random spatial distribution, indicating the lack of any pattern of aggregation or rejection between the species. These results indicated that P. pinea has not spread because it is less able to disperse (strongly barochorus) than P. canariensis (barochorus and anemochorus). Given that the future ability of P. pinea to disperse cannot be predicted, eradication of this species, together with additional plantings of P. canariensis in open areas, is proposed to restore the P. canariensis stand.

Summary Salas Pascual, M., Acebes Ginovés, J. R. & Arco Aguilar, M. del: Arbutus ×androsterilis, a new interspecific hybrid between A. canariensis and A. unedo from the Canary Islands. – Taxon 42: 789‐792. 1993. – ISSN 0040‐0262. Arbutus ×androsterilis, nothosp. nov., results from the hybridization between A. canariensis, a Canary Islands endemic, and A. unedo, a Mediterranean species locally naturalized in Tenerife. The name A. canariensis is typified.

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Background – Species of Agave and Furcraea (Agavaceae, Asparagaceae s. lat.) are widely cultivated as ornamentals in Mediterranean climates. An increasing number is escaping and naturalising, also in natural habitats in the Canary Islands (Spain). However, a detailed treatment of variously naturalised and invasive species found in the wild in the Canary Islands is not available and, as a result, species identification is often problematic.Methods – The present study is based on many years of fieldwork on the islands of Fuerteventura, Gran Canaria, Lanzarote and Tenerife. Results – Fourteen species and several additional infraspecific taxa of Agave have been identified. In addition to the widely naturalised and invasive Agave americana, A. fourcroydes and A. sisalana (incl. the not previously reported var. armata), the following species of Agave were observed: A. angustifolia (incl. var. marginata), A. attenuata, A. filifera, A. franzosinii, A. lechuguilla, A. macroacantha, A. murpheyi, A. oteroi, A. salmiana (var. ferox and var. salmiana), A. aff. tequilana and A. vivipara. From the genus Furcraea three species were found: F. foetida, F. hexapetala and F. selloana. Several of these newly detected species of Agave and Furcraea are at least locally naturalised. A key for the identification of the representatives of these genera in the study area is presented and all species are illustrated. Additional nomenclatural, taxonomic and ecological notes are also provided.