Pteronia anisata B.Nord.

Kolberg, H. & van Slageren, M. 2014. A synopsis of the genus Pteronia (Compositae: Astereae) in Namibia including the resurrection of Pteronia quadrifaria. Kew Bulletin 69: 9488. DOI https://doi.org/10.1007/s12225-014-9488-y

Type

Type: South Africa, Northern Cape Prov., Namaqualand Div., Richtersveld, Cornell's Kop, N slopes, 31 Oct. 1962, Nordenstam 1694 (holotype S-G-5140!; isotypes M-0104529!, PRE, SAM).

Morphology General Habit

Aromatic shrub, to 40 cm high

Morphology Stem

Stems brown when young, dark grey when older

Morphology Leaves

Leaves opposite, clustered along stems, succulent, green with brown resin dots, surface minutely papillate, terete to trigonous to somewhat flattened, to 20 × 1.5 mm, base somewhat clasping with tuft of hairs in axil

Morphology Reproductive morphology Inflorescences Capitulum

Capitula solitary, terminal, cylindrical, to 10 × 6 mm; apex rounded in bud

Morphology Reproductive morphology Flowers Receptacle

Receptacle with lobed and fringed scales

Morphology Reproductive morphology Inflorescences Bracts Phyllaries

Phyllaries 3 – 4-seriate, ovate to oblong, outer 3 × 1.5 mm, inner 10 × 4 mm, green with dark, resinous striations; apex obtuse; margins membranous white

Morphology Reproductive morphology Flowers Florets

Florets to 8; corollas 7 – 7.5 mm long, yellow; lobes triangular with few resin glands on outside; tube puberulous at base

Morphology Reproductive morphology Fruits

Achenes obovoid with constricted apical neck, densely off-white sericeous, 3 – 4 × 2 mm

Morphology Reproductive morphology Seeds Pappus

Pappus of numerous setae united into an annulus at base, 5 – 6 mm long, pale red-brown

Distribution

Africa: Namibia, South Africa. Map 3.

Ecology

On blue dolomite or white quartz outcrops in steppe dominated by succulent species; 200 – 450 m.

Conservation

Pteronia anisata occurs in the protected diamond mining area of Namibia where human access and activities are strictly controlled and limited. Mining occurs in very restricted localities and mostly along the coast, outside the distribution area of this species. Although the estimated EOO and AOO would qualify the species as VU under criterion B, the required two criteria of fragmentation, decline or fluctuation of populations have not been observed. Similarly, under criterion D2 P. anisata is known from fewer than 5 localities but this is not coupled with the required plausible future threat. The species therefore is evaluated as LC in Namibia (IUCN 2001, 2013), but the scarcity of herbarium specimens and information from recent collections suggests that it is rare in Namibia.

Phenology

Flowering: October.

Note

Described in 1971 from the Richtersveld in South Africa (Nordenstam 1971), Roessler & Merxmüller (1982) reported that this species was also recorded in southern Namibia in 1977, some 170 km NNW of the type locality. Only 30 years later the species was found again just north of the Namibian – South African border (Map 3 & Fig. 1). The known distribution of Pteronia anisata suggests that it is near-endemic to Namibia and rare. The specific epithet denotes that the plant smells of aniseed (Nordenstam 1971).