Revision of Slangbos Seriphium plumosum complex: 8 species with 4 new species
https://www.inaturalist.org/taxa/1534922-Seriphium-plumosum
Zaynab Shaik, G.Anthony Verboom, Bengt Oxelman, Nicola G. Bergh, 2024
Revision of Seriphium plumosum (Gnaphalieae: Asteraceae) in southern Africa with description of new species in Seriphium,
South African Journal of Botany 165: 367-383,
https://doi.org/10.1016/j.sajb.2023.12.046.
Abstract
Seriphium plumosum L. from southern Africa has been shown to comprise at least seven distinct species based on analysis of morphological, environmental, and multilocus DNA sequence data. On that evidence, < we reinstate >
Stoebe burchellii Levyns,
Stoebe virgata Thunb., and
Stoebe vulgaris Levyns
and four new species are described, viz.,
Seriphium alto-argillaceum Z.Shaik,
Se. burrowsii Z.Shaik,
Se. crypticum Z.Shaik, and
Se. dunensis Z.Shaik.
Four of these species are endemic to the Cape Floristic Region of South Africa, and one is so far known from a single high-elevation locality. We present a key to species in the Seriphium plumosum complex, and for each species provide a formal description with accompanying images, typification and synonymy, with distribution maps based on verified field-collected and herbarium specimens.
Comments
Koekemoer sank in S. plumosum:
** Stoebe plumosa Thunb., which is widespread in the winter-rainfall zone of the western coastal region of southern Africa,
** St. burchellii Levyns, from the Little Karoo margins in the Western and Eastern Cape of South Africa, and
** St. vulgaris Levyns from the summer-rainfall temperate grasslands of eastern southern Africa.
These are now reinstated.
Some diagnostic and useful features:
** Seriphium alto-argillaceum - small stature, long leaves usually not arranged into fascicles.
** Seriphium dunensis has larger corollas (particularly tube and lobe length, longer involucral bracts longer pappus bristles, and pendulous, paniculate heads than morphologically similar Se. virgatum with erect, sparser heads.
** Seriphium cinereum has long, reflexed leaves, but the similar Se. burrowsii has erect to spreading leaves, & branches at right angles.
** Seriphium vulgaris also has very narrow, linear leaves (like Seriphium cinereum and Se. burrowsii) but is a multi-stemmed resprouter, with acute angled branches.
** Seriphium burchellii - minute, green, awl-shaped leaves, paniculate synflorescences, exclusively foliaceous outer involucral bracts, and smaller corollas, involucral bracts, and pappus bristles (than other species).
Seriphium crypticum, Se. plumosum, and Se. virgatum are very similar, but
** Seriphium crypticum - smaller size (up to 0.5 m tall), more compact growth form, relatively long, densely tomentose, imbricately arranged leaves, dead leaves retained on old branches, and very compact spicate synflorescences of spherical glomerules on terminal elongate axes.
** Seriphium plumosum - larger (up to 1.5 m tall), openly branched growth form, spicate but also paniculate synflorescences, and non-imbricate leaves arranged in well-separated fascicles.
** Seriphium virgatum - erect, generally taller growth form, and diffuse, paniculate synflorescences.
Species:
Cape:
Seriphium alto-argillaceum Hex Snakebush
Distinguished by having adpressed, imbricate, unfascicled leaves that are also much larger with a denser tomentum.
** Alpine, Conical Peak, Hex River mountains.
Seriphium burchellii Smoke Snakebush
Minute (up to 1 (-1.3) mm long), lightly tomentose or glabrous, green, awl-shaped leaves subtending fascicles, and synflorescences that are exclusively paniculate.
** Fynbos around the Little Karoo from Touws River to Langkloof.
Seriphium dunensis Dune Snakebush
Distinguished by large size, supple, flexible and whip-like branches, longer corollas, involucral bracts and pappus bristles, large masses of capitula are borne on pendulous inflorescences, and its grey-white, succulent leaves. (very similar to Se virgatum)
** Unconsolidated coastal dune sands and slacks from Hout Bay to the Fish River valley, below 30 m elevation and near sea.
Seriphium virgatum Limestone Snakebush
Most closely resembles Se. dunensis but is distinguished by features of the leaves, florets, involucral bracts, and branches.
** On limestone and consolidated calcareous soils. From Noordhoek to (very common) on Algulhas Plain to Kariega (PE) in coastal areas on limestone and calcretes (10-55 m elevation).
Seriphium cinereum Karoo Snakebush
Distinctly reflexed leaves, and the leaves are longer than most other species in the complex.
** Peninsula, Hottentots Holland (Franschhoek to Hermanus) and Groot Winterhoek
Seriphium crypticum Hawequas Snakebush
Branching angle always acute, leaves always densely tomentose (imbricate or widely spaced), weakly grouped into poorly defined fascicles.
** Hawekwas (Wellington Sneeukop to Wemmershoek Peak) and Hottenotots Holland (to Victoria Peak) and Riviersonderend (to Jonaskop). Elevations above 1000m.
Seriphium plumosum Common Snakebush
Of 2 elevational morphs (morphologically distinct, but not genetically).
High altitude morph ( > 1000 masl) - branches oriented at an angle less than or equal to 90°, long (to 5.6 mm) leaves subtending the fascicles, and synflorescences of interrupted or continuous spikes.
Low altitude morph (100-1400 masl) - branches oriented at right angles, short (∼1 mm long) leaves subtending the fascicles, and synflorescences of loose panicles or interrupted spikes.
** Distribution (core): common from Nieuwoudtville to Cape Town, and east to Swartberg Pass. Also: on afrotemperate “sky islands” at Windhoek (Namibia) & Huila (Angola). Populations often highly localised and often confined to moist facies.
Summer rainfall region:
Seriphium vulgaris Grassveld Snakebush
Resembles the low-altitude morph of Se. plumosum, but has a subterranean rootstock.
** Widespread and dense stands in Lesotho, Eswatini, Mozambique, Zimbabwe, and the e summer-rainfall region of South Africa, from Umtali (Zimbabwe) to Hogsback (ZA). Seriously undercollected. An indicator of overgrazing in grassveld and savanna.
Seriphium burrowsii Escarpment Snakebush
Has non-reflexed leaves and 90° stem branching angle, and single stemmed below.
** Confined to Buffelskloof Private Nature Reserve and Pilgrim's Rest (Mpumalanga)
Key to Seriphium
.1' Leaves not fascicled, densely tomentose, imbricate and obscuring the stem, 4–7mm long, entire plant grey-green, not whitish; outermost involucral bracts scarious, pubescent; shales above 1800 m on Matroosberg and Conical Peak ... Seriphium alto-argillaceum
.1" Leaves fascicled, lightly to densely tomentose, erect to spreading, loosely imbricate or non-imbricate; leaves subtending fascicles 0.7–8mm long, leaves within fascicles 0.3–3.1 mm long; stem visible between leaves; entire plant green to greyish-white; outermost involucral bracts scarious or foliaceous, pubescent or glabrous ... Goto 2
.2' Synflorescence a loose panicle, never a dense spike, borne at or below the level of the uppermost branches ... Goto 3
.2" Synflorescence a continuous or interrupted spike of glomerules or a diffuse panicle on terminal branches above the level of the uppermost branches ... Goto 5
.3' Leaves green, adaxial leaf surface lightly pubescent, abaxial surface glabrous; leaves subtending fascicles awl-shaped and to 1.3mm; leaves within fascicles granular; stem green, never densely tomentose; synflorescences sparse, erect; outermost involucral bracts foliaceous; above 600 m around northern Little Karoo from Touws River to Langkloof ... Seriphium burchellii
.3" Leaves grey, white, or green, pubescent to densely tomentose; leaves subtending fascicles linear and up to 3.1mm long; leaves within fascicles linear or ovate; branches pubescent to tomentose; synflorescences pendulous or erect; outermost involucral bracts scarious or foliaceous; coastally or near-coastally distributed ... Goto 4
.4' Leaves densely tomentose, grey to white; leaves subtending fascicles linear, up to 2.9mm long; branches supple, flexible, and whip-like; synflorescences pendulous with very many capitula; outermost involucral bracts foliaceous; in littoral dune habitats below 30m from Hout Bay to Fish River valley ... Seriphium dunensis
.4" Leaves pubescent to densely tomentose, green or grey; leaves subtending fascicles linear, up to 3.1mm long; branches erect; synflorescences sparse, erect; outermost involucral bracts scarious or foliaceous; coastal margins below 300m from Noordhoek to Kariega PE) ... Seriphium virgatum
.5' Leaves green, leaves subtending fascicles distinctly reflexed, twisted once, 3.6mm or longer; synflorescence a continuous or interrupted spike of glomerules on terminal and lateral branches; on moist slopes from Franschhoek Pass to Hermanus and Cape Town, & also Grootwinterhoek Mountains ... Seriphium cinereum
.5" Leaves subtending fascicles not reflexed, 0.9–5.6mm long; synflorescence a spike or diffuse panicle ... Goto 6
.6' Leaves in fascicles less than half the length of the leaves subtending fascicles on main stem; plants single-stemmed at or below ground level, not resprouting ... Goto 7
.6" Leaves in fascicles more than half the length of the leaves subtending fascicles on main stem; belowground rootstock present with multiple resprouting stems ... Goto 8
.7' Synflorescence a tight spike of glomerules, never a panicle; upper leaves live, dead leaves retained at base; plants compact, up to 0.5m tall; on slopes and summits in extreme southwestern Cape above 1000m ... Seriphium crypticum
.7" Synflorescence a continuous or interrupted spike of glomerules or a diffuse panicle; dead leaves not retained; plants openly branched; up to 1.5m tall; from Vanrhynsdorp to Cape Town and Swartberg Pass above 60m (also central Namibia & Angola) ... Seriphium plumosum
(8). Branching angle acute; plants up to 1 m tall usually comprising several narrow, resprouting stems; distributed in Lesotho, Mozambique, Swaziland, Zimbabwe, and e ZA summer-rainfall region above 1400m ... Seriphium vulgaris
Branching usually at right angles; tangled shrublet up to 1.5m tall and ≥ 500mm in circumference; stems dense, tangled; escarpment edge, Mpumalanga above 1600m ... Seriphium burrowsii
MAPS:
https://www.inaturalist.org/taxa/map?taxa=1534924,873820,1534925,594442,1534923,1534914,1534927,431651,1534926#6/-27.304/26.015
The map is still a mess. We need to change Seriphium plumosum to plumosum, crypticum (Hawekwas), burchellii (Little Karoo) and vulgaris (non-Cape) (and alto-argillaceum from Matroosberg, and burrowsii from Tvl Escarpment).
Along the coast it should be mainly dunensis (on dunes) and virgatum (on limestone).
Please help push new species names here:
PASS ONE
Summer-rainfall: https://www.inaturalist.org/observations/identify?verifiable=any&taxon_id=431651&place_id=any&preferred_place_id=113055&swlng=25&swlat=-32.9&nelng=37&nelat=-15
Western Cape: https://www.inaturalist.org/observations/identify?nelat=-15&nelng=21&place_id=any&preferred_place_id=113055&subview=map&swlat=-37&swlng=11&taxon_id=431651&verifiable=any
Southern Cape: https://www.inaturalist.org/observations/identify?nelat=-33&nelng=28&place_id=any&preferred_place_id=113055&subview=map&swlat=-35&swlng=21&taxon_id=431651&verifiable=any
PASS TWO
Summer-rainfall: https://www.inaturalist.org/observations/identify?verifiable=any&taxon_id=1534922&place_id=any&preferred_place_id=113055&swlng=25&swlat=-32.9&nelng=37&nelat=-15
Western Cape: https://www.inaturalist.org/observations/identify?nelat=-15&nelng=21&place_id=any&preferred_place_id=113055&subview=map&swlat=-37&swlng=11&taxon_id=1534922&verifiable=any
Southern Cape: https://www.inaturalist.org/observations/identify?nelat=-33&nelng=28&place_id=any&preferred_place_id=113055&subview=map&swlat=-35&swlng=21&taxon_id=1534922&verifiable=any
Two vernaculars appear to have become "unbundled" during all the Latin shenanigans.
Bankruptcy Bush has become applied to Se plumosum, but should be for Se vulgaris, as it is more applicable in Grassveld than in Fynbos.
Karoo Snakebush has become associated with Se cinereum, but should apply to Se burchellii.
Pro Forma (for queries)
Please join family projects at regional level to stay up to date with progress in the families.
In this case, please join:
https://www.inaturalist.org/projects/asteraceae-of-southern-africa/join
& see the journal articles: viz:
https://www.inaturalist.org/posts/91649-revision-of-slangbos-seriphium-plumosum-complex-8-species-with-4-new-species
Please feel free to comment or enquire on the posting.
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