Psoralea fulva C. H. Stirt. & Muasya, 2024

Stirton, Charles H., Bello, Abubakar & Muasya, A. Muthama, 2024, Ten new species and notes on the genus Psoralea L. (Psoraleeae, Fabaceae) from South Africa, Plant Ecology and Evolution 157 (3), pp. 291-312 : 291-312

5. Psoralea fulva C. H. Stirt. & Muasya sp. nov.

Figs 2 , 7

Psoralea sp. 5 (“ Psoralea fulva C. H. Stirt. & Muasya ms. ”, nom. nud.), Stirton and Schutte (2012: 572)

Type.

SOUTH AFRICA – Western Cape Province: 3319 (Worcester) • Kanetvlei valley, Zandrifskloof, Farm Dome Citrus , 3319 (– AD); 33 ° 29 ’ 59.73 ” S, 19 ° 29 ’ 45.21 ” E; 11 Oct. 2009; Muasya & Stirton 4075; holotype: BOL; isotype: NBG .

Diagnosis.

The species differs from Psoralea usitata in its reseeding habit ( P. usitata resprouting); smooth yellowish tan stems with dense vertical rows of white lenticels ( P. usitata grey and coarsely textured); stems give rise to numerous sparsely hairy drooping seasonal shoots each of which terminates in 5–7 small flowers giving its distinctive “ pom-pom ” look (mass-flowering) during the short flowering season ( P. usitata young seasonal shoots stiffly erect arising from the tips of old bare branches giving a terminal shrub-like appearance on the top of the bare stems, each shoot producing flowers sequentially (trap-line) in upper axils); pale mauve standard petals without darker veins and without or with a small central purple flash ( P. usitata purple to dark blue with darker veins and a distinct central purple flash), glabrescent calyx tube longer than the scarcely ribbed greenish yellow teeth ( P. usitata glabrous calyx tube shorter than strongly ribbed purplish teeth).

Description.

Large reseeding shrubs from 2–4 m tall forming large colonies. Stems 1 (– 2), tan with vertical grey lenticels, woody throughout, terete; branches erect, stiff, emerging from near base of plants, producing many erect side branchlets along the stem for first few years giving the plant a brush-like appearance; seasonal shoots erect to arching, arising along the whole branch, smooth, green with pale yellow striations, glandular. Leaves usually absent, if present on post-flowering shoots, then 1 - foliolate, 8–10 × 0.5 mm, conduplicate, covered in minute glands, finely hairy; petiole fused to apex of scales (fused stipules), scales 4 × 0.5–2.0 mm; persistent, appressed, not tightly congested, glandular, teeth 2 mm long, hairy on the inside. Inflorescences complex, pseudo-spicate, comprised of congested terminal clusters of 4–5, short 25–40 mm long shoots, each bearing 2–5 axillary flowers; each cluster subtended by a 30–55 mm long branchlet; pedicel 3–4 mm long, inserted in the cupulum; cupulum stout and rigid, bilobed with one of the vexillar lobes strongly bilabiate appearing trifid, half the length of the pedicel, free from the calyx; glabrous; lobes equally developed, narrowly triangular; base of pedicel hairy. Flowers 12–15 mm long; purple and white; maturing sequentially; basal bracts paired, free, small, 1.5 mm long, triangular. Calyx 7 mm long; tube 3 mm long; glabrous; more or less equal to lateral and vexillar teeth; teeth subequal, the keel tooth slightly longer; the lateral and vexillar calyx teeth acute, falcate, narrowly triangular, the carinal calyx tooth 4 × 2 mm; acute, slightly broader than the other four teeth; the vexillar calyx lobes scarcely fused above the tube; calyx shorter than corolla; ribs distinctly thickened; glands dense, constant in size and equally distributed across the teeth and tube, inside of teeth densely covered in stubby black hairs. Standard petal 11–12 × 11–13 mm; broadly ovate, apex minutely mucronulate, blade mauve to white but darker in upper parts, veins and central flash pale purple, appendages white, paired, prominent, ridged, free; claw 2–5 mm long. Wing petals 11–12 × 6 mm; up-curving with lateral horizontal folds, auriculate; slightly adherent to and longer than keel petals; claw 5 mm long. Keel petals 11–12 × 4 mm; claw 4–6 mm long; apex convex. Androecium 11 mm long, upper end curved inwards, tenth stamen lightly attached, scarcely fenestrate. Pistil 10 mm long, ovary 1 mm long, glabrous, uniovulate, style 7 mm long, swollen at point of flexure, height of curvature 5 mm, stigma penicillate. Fruits 4 × 3 mm, papery, reticulate, wrinkled, style persistent. Seeds 3 × 2 mm, khaki brown with fine black speckles; hilum sub-terminal, aril well-developed, white.

Distribution and habitat.

Psoralea fulva is a reseeding plant restricted to low-lying areas fringing the mountains of the Hex and Breede river valleys within the Western Cape Province (Fig. 2 ). It is allopatric with P. usitata , P. rigidula , and P. fleta which all occur higher up in the mountains. It is sympatric with the pinnately-leaved P. suaveolens C. H. Stirt., A. Bello & Muasya and occurs mostly along streams, gulleys, and seepages in mid montane valleys and in lowland fynbos between 250 and 550 m a. s. l. in the following vegetation types: Breede Alluvium fynbos (FFA 2), Breede Shale Fynbos (FFh 4), North Hex Sandstone Fynbos (FFs 7), South Hex Sandstone Fynbos (FFs 8), and Hawequas Sandstone Fynbos (FFs 10) ( Rebelo et al. 2006).

Phenology and ecology.

Flowering occurs mainly in September and October but also sporadically through to March. Psoralea fulva was incorporated previously as part of Psoralea usitata as Form 4 ( Psoralea sp. 5 ; Stirton and Schutte 2012). The young plants look superficially like P. aphylla , P. fleta , P. gigantea , and P. usitata ( Psoralea sp. 5 ; Stirton and Schutte 2012; Dludlu et al. 2015) during the first few years of growth but as they mature, they develop quite different habits. According to Bello et al. (2017), Psoralea fulva produces occasional spontaneous hybrids with P. suaveolens C. H. Stirt., A. Bello & Muasya (Muasya & Stirton 5931; BOL) where they co-occur in disturbed sandy places alongside streams as they enter the Kanetvlei lowlands. There is also a mixed population of hybrids between P. fleta and P. fulva on the left-hand lower slope on the road from Worcester as it enters the DuToitskloof. This population comprises a great array of flower colours and habits.

Etymology.

The specific epithet fulva (Latin ‘ fulvus’ (- a, - um) = tawny or yellowish brown) alludes to the distinct colour of the stems.

Preliminary IUCN conservation assessment.

This species is locally abundant where it occurs but falls largely out of conservation areas and is mostly on private lands. However, it is now quite scarce along the valley bottoms and persists only around some farm dams and in remaining seepages and drainage ditches in its former lowland habitat which has been transformed into vineyards. It is unlikely to survive on the valley bottoms due to agricultural and urban expansion and so may become restricted in future to the lowest slopes of the surrounding mountains. It is currently assessed as Near Threatened: NT ( IUCN 2012).

Additional material examined.

SOUTH AFRICA – Western Cape Province: 3319 (Worcester) • Kanetvlei valley, Zandrifskloof, Farm Dome Citrus (– AD); 11 Oct. 2009; Muasya & Stirton 4075; BOL • Near De Doorns, Citrus Farm (– AD); 26 Dec. 2007; Muasya & Stirton 3528; BOL • Hex River mountains, Kanetvlei , near Reservoir (– AD); 22 Sep. 2010; Muasya & Stirton 5512; BOL • Hex River Valley (– CB); 21 Feb. 2011; Muasya, Chimphango & Stirton 5930; BOL • Hex River Mountains, Zandrift dam, River bed below (– BC); 11 Oct. 2009; Muasya & Stirton 4079; BOL • Waaihoek turnoff on Worcester - Ceres Road (– CA); 3 Feb. 1981; Walters 2426; NBG • Du Toitskloof Mountains, Delabat Ravine (– CA); 28 Mar. 2009; Muasya, Chimphango & Stirton 4480, 4490; BOL • Du Toitskloof Pass (– BA); 27 Dec. 2007; Muasya & Stirton 3541; BOL • Near bottom of Du Toitskloof Pass (– BA); 10 Oct. 2008; Muasya & Stirton 4071, 4071, 4072, 4073; BOL • bottom of Du Toitskloof Pass on Worcester side (– CA); Esterhuysen 28238; BOL • ibid.; 24 Sep. 2014; Stirton 13995; BOL • Fairy Glen , lower slopes of Brandwagberge (– CB); 19 Sep. 1981; Stirton 9142; PRE • Die Eike Farm, Goudini , 17 Nov. 2011; Stirton 13504; BOL • Rawsonville (– CB); 14 Dec. 1938; Louw 105; NBG • Pokkraal dam (– CB); 21 Feb. 2011; Muasya & Stirton 5939, 5940; BOL • Worcester (– CB); Fine 30; PRE • ibid.; Rehmann 2429; NBG • Farm Eensgevonden, Rawsonville (– CB); 18 Nov. 2011; Stirton 13508; BOL • ibid.; 24 Jul. 2010; Muasya & Stirton 5391; BOL • Watervalkloof in Siduberg, Horlosieberg, Farm Eensgevonden (– CB); 28 Mar. 2009; Muasya & Stirton 4491; BOL • Hex River Mountains near De Doorns , Keurhoek Valley (– CB); 25 Dec. 2007; Muasya & Stirton 3504; BOL • Brandvlei (– CD); 12 Mar. 1985; Van der Kooy 1104; NBG .

Figures

Figure 2. Known distribution of the ten described Psoralea species. Map by Abubakar Bello.

Figure 7. Psoralea fulva. A. Habitat. B, C. Immature non-flowering saplings. D. Flowering plant and habitat. E. Flower buds. F. Bark of stem. G. Axillary flowers terminating seasonal shoots. H. Calyx post corolla drop. Photographs: A – H by Charles Stirton.