Psoralea psammophila C. H. Stirt. & Muasya, 2025

Stirton, Charles H., Bello, Abubakar & Muasya, A. Muthama, 2025, Nomenclatural notes on the genus Psoralea (Psoraleeae, Fabaceae) in South Africa, Plant Ecology and Evolution 158 (2), pp. 168-180 : 168-180

6. Psoralea psammophila C. H. Stirt. & Muasya nom. nov.

Fig. 7

Otholobium incanum C. H. Stirt., South African Journal of Botany 57 (2): 124. 1991. ( Stirton 1991).

Psoralea incana (C. H. Stirt.) C. H. Stirt. ( Bello et al. 2022: 68), nom. illeg.; non Psoralea incana Nutt. ( Nuttall 1818: 102) = Pediomelum argophyllum (Pursh) J. W. Grimes.

Type

SOUTH AFRICA – Western Cape Province: 3118 (Van Rhynsdorp) • 14.8 km NE of Lamberts Bay (– CB); 7 Jul. 1968; Acocks 19782; holotype: PRE [ PRE 0430600 -0]; isotype: K [ K 000392552 ] .

Diagnosis

Psoralea psammophila is closest to P. argentea Thunb. Both have white flowers and silvery digitately trifoliolate and petiolate leaves. Psoralea psammophila differs in its sprawling to virgate habit up to 1 m tall with greyish brown finely fissured branches with sparse white lenticels ( P. argentea a slender woody shrublet with reddish brown branches and flattened pustules); terminal leaflet (10 –) 13–16 (– 22) × 6–9 mm ( P. argentea 7–9 (– 10) × 5–6 mm); stipules sericeous, narrowly triangular, densely glandular ( P. argentea densely hairy, subulate, glandular at base); inflorescences axillary in upper axils of short shoots, pseudo-capitate, 15–25 mm long, comprised of 6–7 triplets of flowers borne on short 1 mm long pedicels ( P. argentea arising from the terminal axil of a 5–12 cm long shoot comprised of 3–4 triplets borne of 1.0–1.5 pedicels); subtending bract of the flower triplets obovate with an acute apex ( P. argentea the subtending bract broadly ovate and acuminate); flowers 8–10 mm long ( P. argentea flowers 7.0– 7.5 mm long); calyx teeth as long as the tube, triangular, hoary ( P. argentea calyx teeth shorter than the tube, falcate, sericeous).

Description

Sprawling to virgate shrublet up to 1 m tall. Stems much branched towards the base; branches greyish brown, finely fissured and sparsely covered in white lenticels; young twigs and flowering shoots pustulate and hoary. Leaves digitately trifoliolate, petiolate. Leaflets unequal, terminal leaflet (10 –) 13–16 (– 22) × 6–9 mm, obovate, hoary; scarcely mucronate, mucro patent, apex rounded to emarginate, base cuneate; laterals smaller than the terminal leaflet, symmetrical; petiole 3 mm long, petiolule <1 mm long. Stipules 1.5–3 mm long, narrowly triangular, densely glandular, straight, apex acute; glabrous inside, sericeous outside, persistent. Inflorescences axillary in terminal axils of short shoots, pseudocapitate, 15–25 mm long, comprised of 6–7 triplets of flowers borne on short 1 mm long pedicels; each set subtended by a single persistent short 1–2 mm long obovate bract with acute apex; peduncle 5–15 mm long, exceeding the subtending leaf. Flowers 8–10 mm long, white, ebracteate. Calyx teeth as long as the 3 mm long tube, equal, triangular; lobes 6 × 1.0– 1.5 mm, vexillary lobes fused up to two-thirds their lengths; hoary, scarcely to sparsely gland-dotted. Standard petals 8–9 × 6.0–7.0 mm, claw 2 mm long; broadly elliptic, distinctly auriculate, apex emarginate. Wing petals 7–8 × 2.0– 2.5 mm, longer than keel petal, claw 3 mm long, distinctly auriculate, sculpturing upper basal and upper central, more pronounced in the upper right central region, transcostal, lamellate, up to 35 curving lamellae in a single row. Keel petals 6–7 × 2.5 mm; claw 3 mm long. Androecium 7–8 mm long, vexillary stamen free. Pistil 7–8 mm long; ovary 2.5–3.0 mm long, pubescent, glandular, sessile; height of curvature 2 mm, style thickened maximally just before flexure, stigma penicillate. Fruits and seeds unknown.

Distribution and habitat

Psoralea psammophila is restricted to the region between Vredendal and Lutzville to Lamberts Bay (Fig. 2 ). It occurs in West Coast Sandveld (Veld Type 34; Acocks 1975) and more precisely in the critical endangered Klawer Sandy Shrubland vegetation type (SKs 13; Mucina and Rutherford 2006; Government Gazette 2022). It occurs between 80–120 m a. s. l. and prefers calcareous sandy soils.

Phenology and ecology

Flowering between August and October.

Etymology

The specific epithet psammophilus is derived from the Ancient Greek words ψάμμος (psámmos, “ sand ”) and φίλος (phílos, “ dear, beloved ”) and is generally translated as sand loving and refers to the fact that this species prefers and thrives in sandy soils.

Preliminary IUCN conservation assessment

Psoralea psammophila was first collected in 1958 by Acocks and since then only two other collections have been made. However, it has not been recorded since it was last seen in 1981, despite regular collecting expeditions to the area, when it was assessed as a rare and localized species (EOO of 57 km 2, classifying it as Critically Endangered, and an AOO of 12 km 2, classifying it as Endangered). No photos are known of this species, and it is only known from Van Rhynsdorp. Given the expansion of agricultural lands for crop cultivation there is certainly ongoing habitat loss. The species is therefore assessed as Critically Endangered: CR B 1 ab (iii, iv) ( IUCN 2012).

Additional material examined

SOUTH AFRICA – Western Cape Province: 3118 (Van Rhynsdorp) • 10.5 km WNW of Vredendal (– CB); 7 Aug. 1968; Acocks 24082; PRE, STE • 17.8 km from Vredendal to Lutzville (– CB); 4 Dec. 1981; Stirton 10131; K, NBG, PRE, STE .

Figures

Figure 2. Known distribution of the six described Psoralea species. Map by Abubakar Bello using QGIS v. 3.28 (QGIS Development Team 2020).

Figure 7. Psoralea psammophila. A. Flowering stem. B. Terminal leaflet. C. Apex of terminal leaflet. D. Side view of flower. E. Standard petal. F. Wing petal. G. Keel petal. H. Pistil. I. Upper part of androecial sheath split to expose staminal arrangement. J. Calyx opened out, inner face. K. Triplet bract. Drawn by Angela Beaumont from Acocks 19782 (PRE).