Polhillia ignota Boatwr., 2010

du Preez, B., Dreyer, L. L., Stirton, C. H. & Muasya, A. M., 2021, A monograph of the genus Polhillia (Genisteae: Fabaceae), South African Journal of Botany 138, pp. 156-183 : 168-169

2. Polhillia ignota Boatwr. ( Fig. 9 ), S. Afr. J. Bot. 76: 143 (2010).

Type: South Africa, Western Cape, Vredenburg (3317): Between Vredenburg and “ Hoetjesbaai ” [ Houdjies Bay ] (— BB), 5 Sept 1928, Hutchinson 253 ( K, holo.!) .

Erect, rounded shrubs 1.0 — 1.5 m tall, sprouting from a woody rootstock. Branches shiny yellow-brown, densely sericeous on young branches, becoming glabrescent on older branches; lenticels absent; terminal burst branching present. Stipules 1.0 — 3.0 mm long, green. Lea fl ets elliptic-narrowly obovate, bright green, adaxial surface sparsely hairy, abaxial surface and margin sericeous mature leaflets flattened, young growth conduplicate, apex obtuse, base cuneate, terminal leaflet 4.0 — 12.0 X 1.0 — 2.5 mm, lateral leaflets 4.0 — 10.0 X 1.0 — 2.5 mm; leaves subsessile. In fl orescence (1 —)2 — 4 flowered terminal cluster, pseudo-pedunculate or rarely subsessile, pseudo-peduncles up to 15.0 mm long; pedicel up to 3.0 mm long; bract 1.0 — 1.5 mm long, linear. Flowers bright yellow, 10.0 — 12.0 mm long. Calyx 4.0 — 5.0 mm long, lime-green, villous; tube 3.0 — 3.5 mm long; dorsal teeth broadly triangular, 1.0 — 1.5 mm long, fused for less than one third of their length, tips acute; ventral teeth triangular, 1.0 — 1.5 mm long, fused, fused for about two thirds of their length, converging, tips apiculate. Standard 10.0 — 12.0 mm long; claw linear, 3.5 — 4.5 mm long; lamina broadly ovate, 7.5 — 9.0 X 9.0 — 12.0 mm, apex emarginate, base cordate; back shortly sericeous on upper parts only. Wing petals 8.0 — 10.0 mm long, ± equal in length to keel; claw 3.0 — 4.0 mm long; lamina lunate, 6.0 — 8.0 X 3.5 — 4.5 mm, glabrous, apex obtuse, base truncate to shortly auriculate, two lunate and one oval depression with lamellate sculpturing. Keel petals 8.0 — 10.0 mm long; claw 3.5 — 4.2 mm long; lamina lunate, 6.0 — 7.0 X 3.0 — 3.5 mm, pilose along fore edge, apex obtuse-rounded, base truncate. Stamens basifixed anthers 1.1 — 1.5 mm long, carinal anther 1.0 mm long, dorsifixed anthers 0.7 mm long; staminal tube 8.0 — 8.7 mm long, unfused portion remaining closely united, sub-erect, tightly arranged around style. Pistil 8.1 — 10.1 mm long; ovary 5.0 — 6.7 X 0.8 — 1.0 mm, ovules 12; style usually at about 70 — 90̊ angle, height of curvature 2.9 — 3.3 mm, sericeous to point of flexure. Fruit indehiscent, plicate, straight to slightly falcate, woody, sericeous, pale-brown, 17.0 — 20.0 X 3.0 — 4.0 mm. Seed ovate-reniform; testa olive-green to dark-brown, smooth, 2.0 — 2.5 X 1.8 — 2.3 mm, 1.6 — 1.9 mm thick.

Etymology

This distinctive species was first recognised by Stirton (1986a) as Polhillia sp. A ., which is morphologically similar to P. obsoleta , but pended describing it until fruits and seeds could confirm its status. Boatwright (2010) formally described it based on this herbarium material only, in order to facilitate indexing and including it in conservation programs and Red Data Listing. The specific epithet “ignota ” alludes to it being ignored until it was eventually described. Fruiting material was only collected in April 2016 by the first author, with flowering material collected in September 2016 to confirm the rediscovery and validity of this being a species in good standing.

Diagnostic characters

Polhillia ignota is morphologically most similar to Polhillia obsoleta . It is distinguished from P. obsoleta by its bright green leaves (versus blue-green leaves); pseudo-peduncles that are up to 15.0 mm long and carry up to four flowers (versus pseudo-peduncles of only up to 8.0 mm long carrying only one or occasionally two flowers); pale brown, densely pubescent fruit (versus russet brown, pubescent-glabrescent fruit); ventral calyx teeth converging (versus ventral calyx teeth spreading); wing petals lunate with three depressions present (versus wing petals obliquely oblong with two depressions present). The geographical distribution of this species is also distinct, as it occurs only in the Swartland, whereas P. obsoleta is restricted to the Breede River Valley around Worcester.

Distribution, ecology and conservation status

Polhillia ignota flowers from August to October. The type collection of this species is from the Vredenburg area along the west coast of South Africa. This area has, however, been extensively transformed by agricultural, industrial and urban development and the species has, most likely, now become extinct in this area. Extensive field surveys throughout this region proved unsuccessful. Its current distribution is restricted to four localities in Swartland Shale Renosterveld (FRs 9) ( Mucina and Rutherford, 2006), where it grows on shales overlaid by alluvial sediment. Two of the locations are in the northern Swartland region around Eendekuil (16 plants) along with a single plant growing in the fence line along the N7 highway 5 km north of Piketberg ( Fig. 10 ). Two further populations were recently discovered south of there in the Vo elvlei € Nature Reserve and southwest of Porterville. Additional individuals from these two new populations brought the known global population size to roughly 230 plants. Over 90% of the Swartland Shale Renosterveld has been transformed for agriculture ( Ebrahim et al., 2016; Mucina and Rutherford, 2006), but we are optimistic more populations may be discovered through more focussed searches in potentially suitable habitat fragments. The Red Data List status of this species was assessed as Endangered (EN A2c; B 1ab(i,ii,iii,iv,v)+ B 2ab(i,ii,iii,iv,v); C2a(i); D) following the latest IUCN categories and criteria ( IUCN, 2012).

Additional specimens examined

South Africa. WESTERN CAPE: 3218 (Clanwilliam): Farm Goedehoop, just south of Eendekuil (— DB), 27 Apr 2016, B. du Preez 186 (BOL); 11 Sept 2016, B. du Preez 192 (BOL); 1 Oct 2017, B. du Preez 349 (BOL); N7. About 5 km north of Piketberg (— DD), 4 Sept 2017, B. du Preez 323 (BOL, PRE). 3318 (Cape Town): Near Porterville (— BB), 27 Dec 1907, Edwards s.n. sub BOL13438 (BOL). 3319 (Worcester): Vo elv- € lei Nature Reserve, in and next to western firebreak (— AC), 8 Sept 2018, B. du Preez 526 (BOL, PRU).

Figures

Fig. 9. Composite plate of Polhillia ignota. 1 — Flower front view; 2 — Flower side view; 3 — Flower bottom view; 4 — Wing petals; 5 — Keel petals; 6 — Androecium; 7 — Gynoecium; 8 — Fruit; 9 — Close-up view of leaves and stipules; 10 — Habit. Scale bars: 4 mm. Photographs by B. du Preez

Fig. 10. Distribution of Polhillia ignota