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| Psoralea forbesiae C.H.Stirt., A.Bello & Muasya, in Stirton, Bello & Muasya, 2018. |
Abstract
Psoralea forbesiae C.H.Stirt., A.Bello & Muasya is a new species of Psoraleeae, Fabaceae. Psoralea forbesiae is endemic to the Swartberg Mountains and is a tall densely branched re-sprouting shrub up to 2.5 m, with bluish-green stems and with most parts covered in small crater-like glands, leaves pinnately 3-foliolate, linear-oblong, pale bluish-green, semi-conduplicate, somewhat succulent, glabrous, crowded at the end of bare branches on older stems or distributed along short branches on young shoots, petiolate. A description of P. forbesiae, together with photographs and a distribution map are presented.
Keywords: Leguminosae , New species, Endemic, Psoralea , Psoraleeae , South Africa, Taxonomy
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| Psoralea forbesiae C.H.Stirt., A.Bello & Muasya: A front view of flower B Fruiting calyces C Side view of flower D Habit E Back of standard F Stipule G Fruiting calyx H Leaf I Stem. Photographs by Charles Stirton and Abubakar Bello. Voucher Stirton & Muasya 13279 (BOL). |
Psoralea forbesiae C.H.Stirt., A.Bello & Muasya, sp. nov.
Psoralea sp. 15, Stirton & Schutte
in Manning & Goldblatt, Strelitzia 29: 574 (2012).
Diagnosis: Similar to P. axillaris L., but differs in being a resprouter with numerous shoots emerging from a woody rootstock; older plants producing a cluster of shoots (burst-branching) at the ends of the previous seasons’ terminal shoots giving an untidy habit (versus a much-branched reseeder with single stem, never with burst branching); stems coarsely fissured and greyish with age (versus furrowed, heavily lenticelled and brownish); leaves 3-foliolate; leaflets partially conduplicate, linear-oblong, with raised crater-like glands and scarcely visible veins (versus leaves 3–5-foliolate; flat, lanceolate, distinctly veined with small sunken glands); lateral leaflets symmetrical, 2–3 mm broad (versus lateral leaflets asymmetrical, 3–8 mm. broad); flowers well exerted from leaves, mauve to pale lavender, wings white (versus mostly hidden within leaves, mauve to purple with purple veins, wings mauve); standard white to pale mauve and with a single purple vertical flash plus a few shorter darker veins towards base of standard, apex greenish on front and back (versus mauve with strongly purple veins and violet basal patch, apex not greenish on front and back); wing petals flared outwards (versus wing petals held vertically).
Distribution, habitat and ecology: Psoralea forbesiae is a locally common species known only from the mid- to upper altitudes on the southern slopes and plateau of the Swartberg Mountains of the Western Cape Province (Fig. 2). It occurs in seepages, gulleys and along streams in mountain fynbos between 1200–1700 m (a.s.l.). It is restricted to the South Swartberg Sandstone Fynbos and North Swartberg Sandstone Fynbos vegetation types (FFs 23 & FFs 24) (Mucina and Rutherford 2006). It forms part of an introgressive hybrid swarm with P. sordida on the flanks of the road leading up the southern slopes of the Swartberg Pass (Bello et al. 2018). The flowers are visited by black Megachilid and Xylocopid bees.
Etymology: The specific epithet forbesiae honours Scottish born Helena Madelain Lamond Forbes (1900–1959) who immigrated to South Africa with her parents when young. She worked at the National Herbarium in Pretoria, visited Kew Gardens for one year and ended up as the Curator of the Natal Herbarium (NH). She wrote local floras of Isipingo and Malvern districts in Natal but is best known for her revisions of Tephrosia and Psoralea in South Africa (see Gunn and Codd 1981, Glen and Germishuizen 2010).
Charles H. Stirton, Abubakar Bello and A. Muthama Muasya. 2018. Psoralea forbesiae (Psoraleeae, Fabaceae), A New Species from the Swartberg Mountains of South Africa. PhytoKeys. 99: 93-98. DOI: 10.3897/phytokeys.99.24765
