Psoralea oreopola C. H. Stirt., 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

10. Psoralea oreopola C. H. Stirt. sp. nov.

Figs 2 , 13 , 14 , Table 1

Psoralea sp. 18 (“ Psoralea oreopola C. H. Stirt. ms. ”, nom. nud.), Stirton and Schutte (2012: 574)

Type.

SOUTH AFRICA – Western Cape Province: 3218 (Clanwilliam) • Cederberg, Middelberg Pass, Kleinfontein extension, Elandskloof ; 5 Nov. 1986; Stirton, Chimphango & Muasya 11488; holotype: BOL .

Diagnosis.

Species similar to Psoralea papillosa C. H. Stirt. & Muasya , from which it differs in its 1.5–2 m tall obovate to broadly obovate habit with multiple stems ( P. papillosa hemispherical habit with 2–4 main stems), seasonal shoots bright yellowish green, glabrous; ( P. papillosa greenish black, bristly pubescent); leaves (2 –) 3 foliolate, basal pair of leaflets shorter than terminal leaflet ( P. papillosa leaves 5 (– 7) - foliolate, basal pair of leaflets longer than the terminal leaflet); stipules subulate, rigid, sharp, senescent but persistent on older leaves, free from base of petiole ( P. papillosa subulate-triangular, recurving, becoming woody when old, tightly recurved, sides reflexed, fused to base of petiole); flowers 1–2 (– 3) per axil, basal bracts or scales absent at base of peduncle ( P. papillosa flowers 1 (– 2) per axil, basal bracts paired and present at base of peduncle); inner face of cupulate teeth finely white-haired ( P. papillosa inner face of cupulate teeth sparsely black-haired); standard petal almost reniform in shape, transversely depressed, 3 times wider than long, appendages large and swollen ( P. papillosa standard petal broadly elliptic, appendages present but scarcely swollen); calyx lobes 7–8 mm long, inside densely covered with white pubescence, carinal tooth same size but broader than the rest of the teeth ( P. papillosa calyx lobes 5.0– 5.5 mm long, inside black-haired in sinuses and midrib area, carinal tooth slightly longer but narrower than the rest).

Description.

Obovate to broadly obovate spreading shrub up to 2 m tall; resprouter, strongly aromatic. Stems numerous, branching from lower and central parts, erect to arcuate, greyish brown with semi-storied lenticels; young seasonal shoots produced in a burst branching manner looking somewhat shrublet-like, bright yellowish green, glabrous. Leaves either 2 - digitately foliolate or slightly pinnately 3 - foliolate, upper rachis 1 mm long, petiole 12–15 mm long, petiolule yellow. Leaflets with terminal longer than lateral pair, 22–33 mm long, <1 mm wide; lateral leaflets equal, 15–25 × 0.5 mm, furrowed on adaxial surface, convex below, surface with slightly raised small yellow glands, margins regular. Stipules 1 mm long, subulate, senescent but persisting in older leaves, glabrous, pungent, sharp, apex acute, angled at 45 ° to shoot. Inflorescences axillary to upper nodes of seasonal shoots, 1–2 (– 3) per axil; peduncle 7–9 mm long. Flowers 10–15 mm long, basal bracts or scales absent at base of peduncle; buds slender, acuminate; cupulum 5–6 mm long, teeth 3 mm, erect, acuminate, teeth equal, appearing bilobed but with abaxial pair deeply cleft, appearing trilobed, adaxial lobe broadest, enveloping the base of flower buds but free once the flower is mature, finely white-haired on inner face, minutely glandular. Calyx lobes 7–8 mm long, yellowish, teeth subequal, carinal lobe slightly longer but narrower than the rest, 4 mm long, outside glabrous, densely glandular between veins, outer teeth glabrous, inside densely covered with white pubescence; tube 5 mm long, slightly longer than teeth. Standard petals 5 × 15 mm, almost reniform in shape, transversely depressed, 3 times wider than long, white, reflexed 90–120 °; nectar patch 2 mm wide, purple stripe with a few short radiating purple arms, arising above the large vertical paired swollen callosities, veins mauve; apex emarginate; claw 2 mm long, broad, straight. Wing petals 11–15 × 5 mm, longer than keel petals, strongly folded along mid line; blade spathulate, auricle well-developed, swollen and anastomosing; sculpturing present along top groove, upper basal, comprising up to 10 curving transcostal lamellae; claw 6 mm long. Keel petals 9 × 4 mm, sharply upcurved, apex acute; claw up to 7 mm long. Androecium 12 m long; tenth stamen free, sheath split adaxially, fenestrate. Pistil 10–11 mm long, ovary 7 mm long, stalked, with small recurved stalked glands, glabrous; style height of curvature 4 mm, thickest at point of flexure, stigma capitate, base fringed with a ring of hairs. Fruits and seeds unknown.

Distribution and habitat.

Endemic to fynbos on montane and lower slopes in the Cederberg in the Western Cape Province, South Africa (Fig. 2 ). A colonial species, it is found mainly on lower slopes, but also on upper sandy table lands and restio plains with occasional Protea laurifolia Thunb. and Protea nitida Mill. (fide Bean & Viviers 1765, BOL). The main soil type is acidic lithosol soil derived from Ordovician sandstones of the Table Mountain Sandstone Group on the Olifants Sandstone Fynbos and Cederberg Fynbos Sandstone vegetation types (FFS 3, FFS 4; Mucina and Rutherford 2006). The distribution is patchy; most of the records are from roadside collections, so it may be more common than its current distribution.

Phenology and ecology.

Flowering occurs from September to January but mainly in December and rarely up to April. Incidences of hybridization involving P. oreopola have been documented at two disjunct localities in the Cederberg mountains. On the Pienaarsvlakte, above Algeria in the Cedarberg, there is a hybrid swarm between P. oreopola and P. intonsa C. H. Stirt., Muasya & A. Bello. The hybrid swarm encompasses a range of intermediate leaf foliolation ranging from 3 - to 7 - pinnate leaflets (Stirton, Muasya & Bello 11489 with 5–7 leaflets; Stirton, Muasya & Bello 11492 with 3 -, 5 -, and 7 - pinnate leaflets). The variation in this population is considerable and shows a range of flower colour intermediates. See Table 1 . Hybridization between these two species (Fig. 14 ) also occurs in the large sandy vlei below the parking lot at the top of Pakhuis Pass above Clanwilliam: Psoralea oreopola , hybrids (e. g. Muasya & Stirton 3272, 3274), and P. intonsa . Variation in this population is more complex than in the Algeria swarm and is complicated by the presence of P. verrucosa . It has not been studied in detail as in our previous studies of hybridization in Psoralea ( Bello et al. 2018) as the area was later burnt and we were unable to revisit.

Etymology.

The specific epithet oreopola is derived from the Greek word ὄρειος (of the mountain) and refers to their preferred locale.

Preliminary IUCN conservation assessment.

Nearly all the existing populations occur in protected areas and only the plants on the lower slopes of valleys along road routes might be affected should changes occur to the landscape or via roadworks. The only perceived threat would be the establishment of new forest plantations and the spread of Pinus L. We consider it as Least Concern: LC ( IUCN 2012).

Additional material examined.

SOUTH AFRICA – Western Cape Province: 3218 (Clanwilliam) • Pakhuis Pass, Clanwilliam (– BA); Nov. 1929; Thode s. n.; PRE • Sandy vlei below the parking lot at the top of Pakhuis Pass above Clanwilliam (– AA); 11 Dec. 2007; Muasya & Stirton 3271; BOL • Heuningvlei, Pakhuis Pass, Cedarberg (– AA); 4 Sep. 2011; Muasya & Stirton 1322; BOL • 3219 (Wuppertal): Uitkyk Pass , Cedarberg (– AA); Dec. 1934; Leipoldt s. n.; BOL, NBG, PRE • ibid.; 3 Dec. 1934; Salter 5077; NBG, PRE • Middelburg Pass, Kleinfontein extension, Elandskloof (– AC); 5 Nov. 1986; Stirton 11488; PRE • Elandskloof, Koue Bokkeveld (– AC); 16 Dec. 1935; Levyns 5142; BOL • Welbedacht Kloof, Cedarberg (– AC); 19 Oct. 1923; Pocock 418; NBG, PRE • NE base of Sneeuberg from Eikeboom farm up to Hoogvertoon , Sederhoutskloof, Cedarberg Forest Reserve (– AC); 5 Dec. 1964; Taylor 6182; NBG, PRE • Top of Uitkyk Pass , Cedarberg , Top end of Die Vlei, between Meid se Berg and Malkopkraal (– AC); 7 Feb. 2009; Muasya & Stirton 4170; BOL • ibid.; 7 Feb. 2009; Muasya & Stirton 4270; BOL • Wolfberg, Cedarberg Mountains (– AC); 7 Feb. 2009; Muasya & Stirton 4376; BOL • Pienaarsvlak above Algeria in Cedarberg (– AC); 7 Nov. 1989; Stirton 11489; PRE • Sneeuberg track above Sederhoutskloof , 9 Dec. 1982; Taylor 10519; K, NBG • Mouton’s Klip, Welbedacht Vlei , Cedarberg (– AC); 5 Nov. 1986; Bean & Viviers 1765; BOL • Top of Duivelkop , Clanwilliam Division (– BA); Jan. 1945; Stokoe 9240; BOL • Top of Middelberg Pass (– CA); 13 Nov. 1985; Snijman 975; NBG, PRE • ibid.; 8 Feb. 2009; Muasya & Stirton 4397; BOL • Middelberg Plateau , Clanwilliam District (– CA); 12 Dec. 1939; Esterhuysen 2471; BOL • Middelberg mountains , Clanwilliam District (– CA); 14 Dec. 1941; Esterhuysen 7191; BOL • Grootberg Summit , Clanwilliam District (– CA); 21 Dec. 1940; Esterhuysen 4188; BOL • South west slope of Cederberg Tafelberg (– CB); 17 Dec. 1950; Esterhuysen 18132; BOL • Grootberg Mountain, near Algeria (– CB); 19 Sep. 1991; Stirton 9190; PRE • 91 km from Op-die-Berg to Clanwilliam (– CB); 19 Sep. 1991; Stirton 9184, 9185, 9187, 9190; PRE • In vlei Cederberg reserve (– CC); 11 Dec. 2007; Muasya & Stirton 3271; BOL .

Figures

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

Figure 13. Psoralea oreopola. A. Colony of plants in typical habitat. B. Habit. C. Bark of old stem. D. Young shoot showing stipule. E. Resprouting shrub after fire showing bright new green growth and old burnt stems. F. Side view of a flower. G. Flower and subtending 3 - foliolate leaves. H. Frontal view of a flower. Photographs: A – F by Charles Stirton; G by Nick Helme; H by Brian du Preez.

Figure 14. Hybrid swarm between Psoralea intonsa and P. oreopola in the large sandy vlei below the parking lot at the top of Pakhuis Pass above Clanwilliam. A. Four different hybrids. B. Hybrid. C. Hybrid. D. Flowering P. intonsa in foreground with non-flowering P. verrucosa around it. E. Group of P. oreopola plants. F. Hybrid. G. White flowers of P. oreopola. H. Hybrid. I. Hybrid. J. Flowering shoot of P. intonsa. K. P. oreopola in foreground and hybrid behind. Photographs: A – K by Charles Stirton.