Lotononis harveyi B.-E.van Wyk

Clark, Vincent Ralph, Bentley, Joanne, Dold, Anthony P., Zikishe, Vathiswa & Barker, Nigel P., 2016, The rediscovery of the Great Winterberg endemic Lotononis harveyi B. - E. van Wyk after 147 years, and notes on the poorly known Amathole endemic Macowania revoluta Oliv. (southern Great Escarpment, South Africa), PhytoKeys 62, pp. 113-124 : 113-115

Lotononis harveyi B.-E.van Wyk Fig. 1 ; Plate 1

Remarks.

Described by William Harvey in Flora Capensis as Buchenroedera spicata Harv. in 1862 ( Harvey and Sonder 1862), this species was collected (without date) by Mrs Elizabeth Mary Barber sometime in the 1800s on the ‘Winterberg’. Three vouchers of this original material exist: one in the Bolus Herbarium (BOL), under her own initials; one in Kew (K) under F.W. Barber, her husband’s initials; and one in Trinity College Dublin Herbarium (TCD), also under her own initials. At the time of Van Wyk’s (1991) ' Synopsis of the genus Lotononis ', this species was still only known from the type material. This remained the case when Clark et al. (2014) published their overview of plant diversity and endemism in the GWA.

Extensive fieldwork by VRC in the Great Winterberg in January 2009 for his PhD resulted in the first recollection of this species since its publication in Flora Capensis, although this was not realised at the time. The specimen (Clark VR, Pienaar C, Daniels R 316; GRA, NBG) was given the tentative identification Lotononis cf. viminea (E.Mey.) B.-E.van Wyk until re-examination in 2014 suggested that it was in fact Lotononis harveyi . A follow-up expedition to find more plants was undertaken on the 6th November 2014, based on the 2009 specimen having been in fruit in January 2009, as it was thought the plants might flower in November-December.

The 2009 site (hereafter Locality 1) was relocated without difficulty, and the search extended southwards down the 19th century wagon trail to the trigonomic beacon and eastwards to the edge of Paradise Kloof (part of the Fenella Falls gorge complex), covering approximately one square kilometre. Despite exploring the area carefully (in the plateau grassland and along the edge of the ravine, as well as in the fynbos and grassland on the steep slopes of the ravine) only six individual plants were found (three in flower, three not).

Key characters confirming rediscovery.

The 2009 specimen was assigned to Lotononis harveyi on the basis of the elongated racemes (therefore not Lotononis trichodes (E.Mey.) B.-E.van Wyk, another local Great Winterberg endemic); the white flowers with densely hairy petals (based on the label information and a few remaining petals on the specimen, as the plant was mostly in pod); the long calyx lobes, hirsute leaves, and long stipules (which match Van Wyk’s 1991 figure 89 very well). The identification was confirmed by the November 2014 plants, especially by the white, hairy petals.

Population assessment.

The plants at the three localities are described separately:

In 2009, two plants were found and collected at Locality 1, recorded as ca. 50 cm tall and with white flowers. This site occupies two square meters and is located on the two meter-wide 'middle man’ between the 19th century wagon trail over the Great Winterberg and the current Finella Falls farm access road. In November 2014, at the same site, three plants were found. One was 45-50 cm tall, branched and in full flower. The other two were 15 cm and 5 cm tall respectively, both damaged on their main axes (probably being the two specimens collected in 2009, one lodged in the Selmar Schonland Herbarium, GRA, and a duplicate to the Compton Herbarium, NBG) but shooting side branches; neither were flowering. Locality 2, situated on the western lip of Paradise Kloof, comprised one plant 15 cm tall, in flower. Locality 3, only a little further back from Locality 2, contained two plants: one 30 cm tall, in flower, the other 20 cm tall, not in flower.

Habit and ecology.

Van Wyk (1991) indicated that the habit of Lotononis harveyi was not known. From the recent collections it can now be stated that it is an erect to spreading woody shrublet 20-50 cm tall, comparing well with Mrs Barber’s notes on her TCD voucher: ' about a foot and a half high - slender with very few branches - perennial '. As was postulated by Van Wyk (1991), it is indeed distinct from the prostrate habit of Lotononis trichodes . Mrs Barber notes on her TCD voucher ' blossoms in autumn ', and as we found the species in full bloom in November, Lotononis harveyi perhaps flowers in sync with the bimodal rainfall regime dominant in this area, i.e. early and late summer ( Mucina and Rutherford 2006).

If the two smaller plants recorded in November 2014 at Locality 1 are indeed the survivors of the two 2009 vouchers, their limited growth since then suggests that the species grows extremely slowly, and this may partly account for its apparent rarity. In contrast, it is surprising that there is no obvious evidence of recruitment despite the floribund inflorescences.

Habitat.

Generally speaking, Lotononis harveyi occurs in Amathole Montane Grassland ( Mucina and Rutherford 2006). The habitat conditions at each locality are discussed separately to identify common ecological factors which may account for this species’ apparent rarity.

Locality 1 consists of a very small area of moribund Themeda triandra Forssk. grassland. Other species present in this area are Cliffortia sp. (50-60 cm tall), Luzula africana Drège ex Steud. and Fingerhuthia sesleriiformis Nees. The remainder of the road reserve comprises the invasive tree Populus x canescens (Aiton) Sm.. The soil is deep and clayey. No plants were evident in the grassland on either side of the road reserve: these grasslands comprise well-gazed Themeda triandra grassland studded with tall Festuca costata Nees tussocks. The gradients are gentle, soils deep and rich, there is limited rockiness, and the grass is probably burnt on a regular basis to limit the spread of the unpalatable Festuca costata .

Locality 2 comprised (prior to burning) Tenaxia disticha (Nees) N.P.Barker & H.P.Linder (= Merxmuellera disticha (Nees) Conert)- Themeda triandra - Festuca costata grassland with the fynbos elements Erica leucopelta Tausch, Searsia rosmarinifolia (Vahl) F.A.Barkley, and shrubs/trailers such as Rubus ludwigii Eckl. & Zeyh. subsp. ludwigii and Rubus rigidus Sm.. The edge of the plateau comprises rocky sandstone outcrops favoured by the fynbos elements, while away from this the soil is a deeper, loamy clay.

Locality 3 comprises moribund Tenaxia disticha - Themeda triandra - Festuca costata veld with scattered Arrowsmithia styphelioides DC. dwarf shrublets and Helichrysum splendidum (Thunb.) Less.. Fire has evidently been absent for some time.

Mrs Barber’s TCD voucher notes that her specimens grew ' amongst the rocks and long grass ' and in ' good soil '. This - together with the six plants all being found in fire-exclusion areas or moribund grassland - suggests that the species is susceptible to fire and possibly grazing pressure. There is no currently no indication on whether this species is a resprouter or a reseeder, and research into the autecology of this species is warranted.

Conservation status and threats.

Lotononis harveyi is currently listed as Data Deficient ( Victor and Dold 2005). Based on our observations we suggest that it be considered 'Critically Endangered’ until more surveys in the general area are carried out. Currently virtually nothing about its biology is known, and accordingly no concrete conservation recommendations can be made. Possible general threats are the over-use of fire (a fire management history of the relevant farms can probably be obtained to indicate fire frequency), although fire has been a natural part of the ecology of these mountains well prior to the discovery of this species.

The general area is vulnerable to invasion by Rosa rubiginosa L. (a fast-emerging invader, with several seen in Localities 1 & 3) and Pinus patula Schltdl. & Cham. (Locality 2), while Locality 1 is in danger of being overrun by Populus x canescens . The targeting of mountain environments for wind farms in South Africa is another concern, with potentially detrimental impacts on localised endemics such as Lotononis harveyi .

Areas for further exploration.

A more exhaustive search along the rugged, extensive rocky rims of the Fenella Gorge area and perhaps on the (still unexplored) slopes of Mount Frederick and Besterskop (the promontory below the main Great Winterberg peak) and the scarp slopes below The Ruitjies might produce more plants. In fact, much of this area has still to be explored botanically, particularly from Mount Frederick-Besterskop eastwards along the scarp below The Ruitjies. The relevant localities/properties are summarised as follows (taken from 1:50 000 sheet 3226AD Spring Valley): Finella Falls 1 (parts of this farm were well surveyed in 2009, but there are extensive rocky areas not yet explored); the scarp margins on the Bosch River Spruit 26; Petraea 2 (being the south-western slopes of Mount Frederick and Besterskop); Oribi Fountains 3 (also being the south-eastern slopes of Mount Frederick and Besterskop, as well as the south-facing scarp of The Ruitjies); and those portions of Emerald Hill 26 and adjacent farms that comprise the ‘Groenberg’.

Collections and localities.

South Africa, Eastern Cape Province, 3226AD, Farm Emerald Hill 26, Great Winterberg (Adelaide): grassland in road reserve on farm track towards Fenella Falls. 32°22'34"S, 26°20'28"E, 1616 m, 23 January 2009. Clark VR, Pienaar C, Daniels R 316 (GRA, NBG) (= Locality 1).

-Eastern Cape Province, 3226AD, Farm Emerald Hill 26, Great Winterberg (Adelaide): grassland in road reserve on farm track towards Fenella Falls. 32°22'25"S, 26°20'24"E, 1649 m, 6 November 2014. Clark VR, Bentley L 9 (= Locality 1; the same population as above, but the 2009 GPS and altitude were a generic reading taken for plant collections along the entire road, and are not as accurate as these provided here. Only photographs were taken of these plants).

-Eastern Cape Province, 3226AD, Farm Bosch River Spruit 26, Great Winterberg (Adelaide): plateau grassland. 32°23'42"S, 26°21'04"E, 1616 m, 6 November 2014. Clark VR, Bentley L 11 (GRA) (= Locality 2; only this plant was collected as a voucher specimen, as the landowner indicated that this area was to be burnt the following day).

-Eastern Cape Province, 3226AD, Farm Emerald Hill 26, Great Winterberg (Adelaide): moribund grassland on the plateau. 32°23'42"S, 26°21'04"E, 1619 m, 6 November 2014. Clark VR, Bentley L 12 (= Locality 3; only photographs were taken of these plants).

Figures

Figure 1. Localities of Lotononis harveyi B. - E. van Wyk and Macowania revoluta Oliv. in the Great Winterberg-Amatholes, Eastern Cape, South Africa. Cartography by J. Bentley.

Plate 1. The first ever photographs of the Great Winterberg-Amatholes endemic Lotononis harveyi B. - E. van Wyk A flower detail (Clark VR, Bentley L 9) B habit (Clark VR, Bentley L 9; the Garmin GPS indicates scale) C montane grassland habitat, with Lotononis harveyi in the middle foreground (Clark VR, Bentley L 11) D complete and open inflorescences (Clark VR, Bentley L 12). Photographs by V. R. Clark.