Scielo RSS http://www.scielo.org.za/rss.php?pid=0006-824120230001&lang=en vol. 53 num. 1 lang. en http://www.scielo.org.za/img/en/fbpelogp.gif http://www.scielo.org.za http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0006-82412023000100001&lng=en&nrm=iso&tlng=en BACKGROUND AND OBJECTIVES: Deforested and degraded areas can be cheaply and conveniently restored through establishment of exclosures. An area exclosure excludes animals and humans from accessing an area to promote natural regeneration of plants and rehabilitate ecological condition of the area. The study was aimed at: (1) determining the diversity (species richness, diversity and evenness); (2) assessing the stand structure (densities); and (3) assessing regeneration status of woody species inside and outside exclosed Maun International Airport, northern Botswana METHODS: Vegetation sampling was conducted from April to May 2018. A total of 48 and 37 quadrats of 20 x 20 m were laid down at 50 m intervals along transect lines inside and outside Maun International Airport, respectively. Identity, number of all live individuals and height of all woody species were recorded in all the quadrats. The diversity of all woody species was analysed by using the Shannon Diversity Index (H') and regeneration status of each woody species was assessed using frequency distribution of height class RESULTS: The diversity, evenness and species richness were significantly higher inside than outside Maun International Airport. Colophospermum mopane was the most abundant species both inside (75% of all woody species) and outside (96% of all woody species) Maun International Airport. More species showed more regeneration inside than outside Maun International Airport. The inside of Maun International Airport recorded more alien invasive woody species compared with the outside, owing to its original use as a residential area. The local communities might have introduced these species as ornamental trees CONCLUSION: This study, while limited in scale, contributes to understanding of the role of exclosures in enhancing woody species richness, diversity and evenness as well as facilitating regeneration of woody species. Degraded woodlands and other similar ecosystems could be cheaply and conveniently restored through establishment of exclosures, but more research and monitoring are required to fully understand the processes and impacts http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0006-82412023000100002&lng=en&nrm=iso&tlng=en BACKGROUND: The genus Amaranthus is taxonomically complex because of its high morphological variability, which led to nomenclatural confusion, misapplication of names and misidentifications. Unfortunately, floristic and taxonomic studies on this genus are still incomplete. A population of Amaranthus crassipes subsp. warnockii was discovered in Monastir Governorate, Tunisia, representing the first record for both the Tunisian and the African floras, as well as the first one outside of its American native distribution area OBJECTIVES: The main aim of the present study was to record Amaranthus crassipes subsp. warnockii (I.M.Johnst.) N.Bayón in Tunisia and Africa for the first time. Morphological characters and ecological data were provided. Clarification about the typification of the names Amaranthus crassipes, A. warnockii and Scleropus amaranthoides was also presented METHODS: The work was based on field surveys, analysis of relevant literature and examination of specimens preserved in the herbaria GH, HAL, P RO, NY, US and the Herbarium of the Faculty of Pharmacy of Monastir (Monastir University RESULTS: Nomenclatural notes were provided for Schlechtendal's A. crassipes (lec-totype at HAL, designated by Henrickson in 1999 but here corrected according to Art. 9.10 of the ICN); Schrader's Scleropus amaranthoides [a superfluous and illegitimate name (Arts. 52.1 and 52.2 of the ICN) and regarded as a homotypic synonym of A. crassipes s.str.]; and Moquin-Tandon's Scleropus amaranthoides [an invalid name (Art. 36.1a of the ICN CONCLUSION: Amaranthus crassipes subsp. warnockii is an alien species in Tunisia, growing in human-made habitat on clayey and sandy substrates within ruder-al vegetation where it can be considered a casual. We hope that in the future continuous monitoring of the population will take place, to verify the possible naturalisation and spread of this taxon in Tunisia. If the latter happens, actions for eradication of the plants are needed http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0006-82412023000100003&lng=en&nrm=iso&tlng=en The new combination Coleus leemannii (N.Hahn) A.J.Paton is provided for Rabdosiella leemannii N.Hahn (Lamiaceae: Ocimeae) from South Africa, a species that was overlooked in the recent synopsis of subtribe Plectranthinae. http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0006-82412023000100004&lng=en&nrm=iso&tlng=en BACKGROUND: Sorocephalus imbricatus (Thunb.) R.Br. is a range-restricted species endemic to the Cape Floristic Region (CFR), South Africa. It is currently classified as Critically Endangered in accordance with the IUCN criteria. Like many other species endemic to the CFR, S. imbricatus is subjected to several major threats including habitat loss, habitat degradation and the impacts of invasive alien species. Sorocephalus imbricatus was recently identified as a species requiring improved representation in ex-situ collections. During field work undertaken to collect germplasm for this purpose, a concerning number of dead and dying plants were observed. OBJECTIVES: To determine the cause of rapid death of individuals in a remnant subpopulation of S. imbricatus. METHOD: A field visit to a subpopulation of the only extant population, Elands-kloof, was conducted to examine the symptoms associated with S. imbricatus mortality, and to collect samples for isolation and identification of putative pathogens. RESULTS: Dead and dying plants showed clear symptoms of root and collar rot, with Phytophthora cinnamomi Rands recovered from all samples. The collections highlighted the severe impact of P. cinnamomi on S. imbricatus, with the size of the subpopulation being reduced from 62 to 37 individuals (a 40% reduction) between October 2021 and May 2022. CONCLUSION: This study describes, for the first time, rapid mortality of the Critically Endangered Proteaceae species, S. imbricatus, likely caused by the invasive pathogen P. cinnamomi. This concerning discovery highlights the urgent need for greater recognition of the threat P. cinnamomi poses not only to S. imbricatus, but to the broader floristic diversity of the CFR. Importantly, it illustrates a need for a substantial body of work to be undertaken to address a significant lack of knowledge regarding the relative threat that P. cinnamomi poses to species of the CFR. http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0006-82412023000100005&lng=en&nrm=iso&tlng=en The new combinations Colchicum burchellii (Baker) J.C.Manning & Vinn. and C. burchellii subsp. pulchrum (Schltr. & K.Krause) J.C.Manning & Vinn. are provided for the taxa currently known respectively under the names C. coloratum subsp. burchellii (Baker) J.C.Manning & Vinn. and C. coloratum J.C.Manning & Vinn., nom superfl. http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0006-82412023000100006&lng=en&nrm=iso&tlng=en The new combination Coleus leemannii (N.Hahn) A.J.Paton is provided for Rabdosiella leemannii N.Hahn (Lamiaceae: Ocimeae) from South Africa, a species that was overlooked in the recent synopsis of subtribe Plectranthinae. http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0006-82412023000100007&lng=en&nrm=iso&tlng=en The first record of the non-native, naturalised Launaea arborescens (Batt.) Murb. in the Namib Desert raised questions of its origin and whether or not it could pose a threat to the indigenous vegetation. The North African plant was introduced in a forestry nursery in the Kuiseb Delta, and some individuals were also planted outside the nursery in the early 1970s. They have maintained a likely viable population for nearly 50 years but have so far not been observed elsewhere and thus appear not to be spreading. http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0006-82412023000100008&lng=en&nrm=iso&tlng=en BACKGROUND: South African brambles (Rubus L., Rosaceae) represent a complex group of six native species and at least 12 introduced taxa with different ploidy levels and varying tendencies to hybridisation. The role of hybridisation, intro-gression and apomixis in the ongoing evolution has been hypothesised based on morphological observations, but it has not been rigorously studied to date, and nor has the phylogeny of the group. OBJECTIVES AND METHODS: This paper aims to reveal the evolutionary patterns and mechanisms in South African brambles by employing three types of molecular markers: plastid and nuclear ribosomal DNA sequences, and nuclear micro-satellites. RESULTS: The data confirmed the tetraploid R. thaumasius A.Beek and diploid R. ludwigii Eckl. & Zeyh. as distinct native species, while the other four native species are shown to be closely related and likely derived from three ancestors. CONCLUSION: Ancient hybridisation and limited gene flow between regions (particularly between winter- and summer-rainfall zones) appear to be the main drivers of current patterns in the tetraploid R. pinnatus Willd. and hexaploid R. rigi-dus Sm. Current hybridisation is also likely, although rare. The mechanism of 'octoploid bridge' is proposed, which overcomes the ploidy reproduction barrier between R. pinnatus (or other tetraploids) and R. rigidus. No gene flow was detected between native and alien taxa, but clonal duplications were discovered in the R. bergii x pinnatus hybrid, which implies the possibility of apomictic spread of homoploid hybrids formed between native and introduced brambles and the potential for a new invasion. On the other hand, heteroploid hybrids (R. bergii x rigidus) are formed recurrently and spread only vegetatively.