Achyranthemum N.G.Bergh, 2019

Bergh, N. G. & Manning, J. C., 2019, Achyranthemum N. G. Bergh, a new genus segregated from Syncarpha DC. (Asteraceae, Gnaphalieae) *, South African Journal of Botany 125, pp. 434-456 : 440

Achyranthemum N.G.Bergh , gen. nov.

Type species: Achyranthemum paniculatum (L.) N.G.Bergh

Helichrysum [unranked] Paniculatae [as ‘ Paniculata ’] Harv. in Fl. Cap. 3: 225 (1865). Type: H. paniculatum (L.) Willd. = A. paniculatum (L.) N.G.Bergh, lecto., designated here.

Diagnosis: Perennial shrublets; abaxial or both leaf surfaces with a grey-white, usually dense and sheathing indumentum of hairs; capitula homogamous, discoid; involucral bract stereomes undivided, laminae papery and shiny; receptacles epaleate; apical anther appendages mucronate to caudiculate, cypsela twin hairs ± hemispherical and without a swelling cushion; pappus bristles fused into a smooth ring at the base, shaft nude to scabrid, apex scabrid to barbellate.

Low, sparsely branched subshrubs, usually 0.2–0.7 m high but up to 1.2 m, woody below, branching mostly near base, stems simple or sparsely branched above, new growth initiated from below previous year’ s synflorescence. Leaves alternate, laxly to densely imbricate, sessile, basal portion apressed or decurrent, distal portion erect to spreading, sometimes incurved or apically recurved, linear to oblanceolate, ± concave or conduplicate, size variable, 8–35(–65) × 0.8–3.0(–5.0) mm, margins flat or narrowly involute, usually mucronate or sometimes pungent, firm-textured or rigid, abaxial or both leaf surfaces with a dense (rarely sparse) indumentum of grey-white or silvery hairs, usually cohering to form a reticulating sheath-like layer. Capitula terminal, (1–)3 to 12(–40) in corymbiform synflorescences, spherical or cylindrical, 7–18 × 4–18 mm, sessile in bud but usually pedunculate at maturity, individual peduncles slender, branched or unbranched, 2–60 mm long, variously hairy, subtended by a basal leaf and often bearing one or two bracteoles. Involucral bracts ± 40 to 120 in ±6–9 series, with a distinct stereome and lamina, stereome undivided, cartilaginous, strongly curved, concave, thickened and tinged reddish-purple, abaxially with a patch of woolly hairs, size relative to lamina increasing acropetally; lamina and margins thin, glabrous, shiny and papery, white, cream, or yellow, frequently tinged pink when immature, rarely rose-pink at maturity, progressively narrower acropetally; outermost involucral bracts erect or squarrose at maturity, broadly lanceolate, stereome small, lamina and margins translucent, lamina apically acute, somewhat keeled; most bracts in middle series, erect sometimes becoming squarrose, linear-lanceolate to narrowly oblanceolate, overtopping florets, with small ovate stereome bearing a patch of dense white hairs; bracts in innermost series sparse, smaller than outer and middle, erect, equalling florets, stereome linear, cartilaginous with dark purple-brown steaks and glabrous or with a patch of long, tangled white hairs on the abaxial apex, lamina as in outer bracts but short and obtuse. Receptacle flat, shallowly tubercled or honeycombed. Florets ±(20–)40 to 90(–150), hermaphrodite, corolla not or slightly expanded apically, yellow, lobes small, recurved after anthesis, narrowly triangular, acute with marginal vascular trace, abaxially bearing small globose trichomes; anther apical appendage acuminate to caudiculate. Cypselae cylindrical, dark reddish-brown, bearing hemispherical myxogenic twin hairs without a swelling cushion. Pappus bristles united at base into a smooth ring, shaft barbellate, apex nude but ends of apical cells inflated and enlarged forming acute, barb-like projections, frequently appressed. Basic chromosome number: unknown.

Species 7, almost restricted to the Core Cape Floristic Region of South Africa, with most taxa centred on the coastal plain in the Algoa Bay area.

Key to the species of Achyranthemum :

1. Leaves with a dense sheath-like layer of thick, long silvery-white arachnoid hairs that cohere to form shiny , ropy longitudinally oriented reticulating strands.......................................................................................................2

1'. Leaves not as above: either with a thick layer of tangled villous hairs, or with a very thin layer of fine, cohering grey-white hairs; or with a sparse- to dense covering of long non-cohering, non-tangled, straight whitish hairs...................................................................................................3

1. Capitula strictly solitary.................................................................................3. A. recurvatum

2'. Capitula in groups of at least 2, rarely a plant with some solitary capitula..............................................................................................................................4

3. Stems below synflorescences sparsely leafy; inner involucral bracts white, outer bracts white and deep rose-pink; rarely all bracts white..................................................................................................................................5. A. affine

3'. Stems below synflorescences densely leafy; involucral bracts whitish (white, cream or greyish) or yellow....................................................5

4. Involucral bracts yellow, sometimes inner bracts flushed pink when immature............................................................................................................2. A. mucronatum

4'. Involucral bracts white, sometimes inner bracts flushed pink when immature...............................................................................................1. A. paniculatum

5. Peduncles shortly grey-felted but lacking long spreading hairs...6

5'. Peduncles dark reddish-brown and densely covered with very slender, long, spreading whitish hairs................................................................7. A. striatum

6. Leaves with a thick loose indumentum of tangled villous hairs; involucral bracts cream to very pale yellow becoming greyish with age, capitula narrowly cupulate, up to 10 mm long; corolla tube 6.5–7.0 mm long...........................................................................................................6. A. sordescens

6'. Leaves with a thin sheath-like layer of long silvery-white arachnoid cohering hairs; involucral bracts bright white or cream, remaining so on drying, capitula spherical, 12–18 mm long; corolla tube up to 6 mm long.......................................................................................................................4. A. argenteum