Abstract
Background: The grasses (Poaceae) of the Flora of Southern Africa (FSA) region (i.e. Botswana, Eswatini, Lesotho, Namibia and South Africa) are relatively well documented, for both native and non-native species. Visiting taxonomic expertise nevertheless reveals new FSA and in-country records, particularly of non-native species. Such records provide an opportunity for improving biosecurity relating to potentially invasive but hitherto undetected non-native Poaceae in the FSA region.Objectives: To improve floristic data for non-native Poaceae occurring in theFSA region.Method: Field collections were made, herbarium collections, databases and relevant literature were studied.Results: New records are presented for non-native grasses that were encountered as locally common populations in the Drakensberg Mountain Centre of Floristic Endemism (DMC, Lesotho and South Africa). Festuca rubra and Agrostis capillaris are newly reported for sub-Saharan Africa and southern Africa and are also the first verified specimens reported for the African continent, with previous reports from northern-most Africa (Morocco, Algeria and/or Tunisia) uncertain. Jarava plumosa, introduced from South America and previously known for the whole of Africa from a single population in the Western Cape, South Africa, is newly reported from the border between the Eastern Cape, South Africa and Lesotho. The ecological implications, including the potential to become invasive, are discussed for each species, with taxonomic notes given to help differentiate them from closely resembling taxa.Conclusion: These new records of alien grass species raise concerns over their potential ecological impact, particularly as they are found in an area of conservation importance. Future efforts to monitor their distribution are of importance.
Highlights
Visser et al (2017) notes that there is much uncertainty regarding the identity, numbers of species, distributions, abundances and impacts of alien grasses in the Flora of Southern Africa (FSA) region, with only 37 of the known 256 non-native species in the region considered to be invasive. Despite this lag in non-native Poaceae knowledge, South Africa has some of the most progressive invasive species legislation in the world, including for known invasive Poaceae: 18 species are listed in the National Environmental Management: Biodiversity Act’s Alien and Invasive Species Lists (2016)
The new records were collected during extensive fieldwork conducted by SPS, RJS, MDPVS and AM in the DMC between 1 Feb. and 9 Mar. 2020, with specimens deposited in the P. Sylvester et al 3451 (PRE), NU and US [exported, awaiting accession] herbaria (Herbarium acronyms follow Thiers [continuously updated])
Herbarium study was conducted at PRE between 13 and 20 Mar. 2020
Summary
The grass family Poaceae is relatively well-documented for the Flora of Southern Africa (FSA) region (comprising Botswana, Eswatini, Lesotho, Namibia and South Africa), with old and recent country-level treatments (e.g. Gibbs Russell et al 1990; Fish et al 2015) that incorporated efforts of numerous researchers who focused on different individual genera (Fish et al 2015, see references therein), as well as more recent treatments of individual genera e.g. Anthoxanthum L. (Mashau 2016); Festuca L. (Sylvester et al 2020a); Poa L. (Soreng et al 2020).In many countries, grasses have become the most damaging of invasive plants (D’Antonio & Vitousek 1992; D’Antonio et al 2011; Gaertner et al 2014), with knowledge of the distribution and ecology of these non-native grasses http://abcjournal.org | | Open accessPage 2 of 9 | Short communication crucial for effective habitat management (e.g. Gaertner et al 2014; Visser et al 2017; Monnet et al 2020). Visser et al (2017) notes that there is much uncertainty regarding the identity, numbers of species, distributions, abundances and impacts of alien grasses in the FSA region, with only 37 of the known 256 non-native species in the region considered to be invasive. The DMC, covering some 40 000 km, contains the only true alpine region in Africa south of Mount Kilimanjaro (Carbutt 2019) These high-elevation Afromontane and alpine areas are renowned for their high levels of plant diversity and endemism, with the DMC hosting ± 2 520 angiosperm species (Carbutt & Edwards 2004) of which 227 are endemic (Carbutt & Edwards 2006; Carbutt 2019). Such records provide an opportunity for improving biosecurity relating to potentially invasive but hitherto undetected non-native Poaceae in the FSA region
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