International audience[No abstract available

This paper aims to provide a baseline for conservation planning by documenting patterns of plant diversity and vegetation in the upper catchment of the Cuito River. 417 species are recorded from this region. Nine of these are species potentially new to science. Ten species are newly recorded from Angola, with an additional species only recorded previously within Angola from the northern enclave of Cabinda. The 108 new provincial records for Moxico clearly indicate the lack of collections from Angola’s largest province. We note the existence of extensive peat deposits in the Cuito river system for the first time and suggest that one of Barbosa’s vegetation types in the area needs to be reassessed.

Five nickel hyperaccumulators belonging to the Asteraceae are known from ultramafic outcrops in South Africa. Phytoremediation applications of the known hyperaccumulators in the Asteraceae, such as the indigenous Berkheya coddii Roessler, are well reported and necessitate further exploration to find additional species with such traits. This study targeted the most frequently occurring species of the Asteraceae on eight randomly selected serpentinite outcrops of the Barberton Greenstone Belt. Twenty species were sampled, including 12 that were tested for nickel accumulation for the first time. Although the majority of the species were excluders, the known hyperaccumulators Berkheya nivea N.E.Br. and B. zeyheri (Sond. & Harv.) Oliv. & Hiern subsp. rehmannii (Thell.) Roessler var. rogersiana (Thell.) Roessler hyperaccumulated nickel in the leaves at expected levels. A new hyperaccumulator of nickel was discovered, Senecio conrathii N.E.Br., which accumulated the element in its leaves at 1695 ± 637 µg g−1 on soil with a total and exchangeable nickel content of 503 mg kg−1 and 0.095 µg g−1, respectively. This makes it the third known species in the Senecioneae of South Africa to hyperaccumulate nickel after Senecio anomalochrous Hilliard and Senecio coronatus (Thunb.) Harv., albeit it being a weak accumulator compared with the latter. Seven tribes in the Asteraceae have now been screened for hyperaccumulation in South Africa, with hyperaccumulators only recorded for the Arctoteae and Senecioneae. This suggests that further exploration for hyperaccumulators should focus on these tribes as they comprise all six species (of 68 Asteraceae taxa screened thus far) to hyperaccumulate nickel.

The Tankwa Karoo National Park has been enlarged from 27 064 ha to 143 600 ha. This whole area is severely under-collected for plants in general and therefore it was an obvious target for the South African National Parks (SANParks) Programme, a component of the Pretoria National Herbarium (PRE) Plant Collecting Programme. This programme not only aims to survey national parks that have been poorly surveyed, but also inadequately known taxa, unique habitats, remote and inaccessible areas and plant species flowering at irregular times, especially after events such as fire or unusual timing of, or high, rainfall. General collecting in the Tankwa Karoo National Park has already led to the description of two new taxa, from two families. It furthermore resulted in new distribution records for the park and for the Northern Cape Province. These are reported on here.Conservation implications: Although the Tankwa Karoo National Park falls within the Succulent Karoo Biome (a biodiversity hotspot of international importance), information on its plant diversity is insufficient because it is an under-collected area. Results of this study will guide conservation and supply occurrence and distribution data required to compile management plans for the park.