Polhillia C.H.Stirt. subgen. Polhillia

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 : 165

4.4. Polhillia C.H.Stirt. subgen. Polhillia

4.4.1. Taxonomy

Type species: Polhillia obsoleta (Harv.) B.-E.van Wyk (= Polhillia waltersii (C.H.Stirt.) C.H.Stirt. )

Shrubs erect or spreading, sprouting from rootstock after fire; stipules 2, deltoid, sericeous, veins not visible, connate around base, sheathing stem, often persistent; leaves subsessile or petiolate in P. brevicalyx , pubescent, conduplicate (or flattened in P. ignota ); flowers single, paired or in clusters (4 — 5 in P. brevicalyx , P. ignota and P. fortunata ), subsessile or pseudo-pedunculate up to 15 mm long; flowers yellow, 8 — 13 mm long; calyx yellow-green, often flushed red, villous or sericeous; standard broadly ovate, apex emarginate, pubescent abaxially; wing petals variable in shape and sculpturing, mostly glabrous or pilose along midrib; keel petals variable in shape and level of pubescence, usually restricted to the fore edge; pistil green, sericeous or villous, ovules 7 — 12, style sub-erect to erect; fruit indehiscent, oblong, laterally compressed between seeds, plicate in P. ignota , P. obsoleta , P. groenewaldii , and P. fortunata , sericeous to glabrescent; seeds ovate-reniform, smooth, uniformly coloured, olive green to dark brown (except for P. connata and P. pallens that have occasional mottling).

4.4.2. Species included

1. Polhillia brevicalyx (C.H.Stirt.) B.-E.van Wyk & A.L.Schutte

2. Polhillia connata (Harv.) C.H.Stirt.

3. Polhillia curtisiae C.H.Stirt. & Muasya

4. Polhillia fortunata B.du Preez

5. Polhillia groenewaldii B.du Preez

6. Polhillia ignota Boatwr.

7. Polhillia obsoleta (Harv.) B.-E.van Wyk

8. Polhillia pallens C.H.Stirt.

9. Polhillia stirtoniana B.du Preez

10. Polhillia xairuensis B.du Preez

4.4.3. Etymology

The generic and subgeneric epithet Polhillia honours the renowned botanist and legume systematist Dr. Roger M. Polhill from the Royal Botanical Gardens, Kew ( Stirton . 1986a).

4.4.4. Diagnostic characters

The genus is divided into two subgenera: Polhillia and Roseopolhillia (this paper). The ten species in Polhillia subgen. Polhillia are distinguished from the single species in the new subgen. Roseopolhillia by having yellow flowers (versus pink or rarely white flowers); indehiscent fruit (versus dehiscent fruit); leaves and stipules entirely sericeous-canescent or villous (versus leaves mostly glabrous, and stipules pubescent only villous on adaxial surface, glabrous on abaxial surface).

4.4.5. Distribution of Polhillia subgen. Polhillia

Species in Polhillia subgen. Polhillia are distributed through lowland Renosterveld vegetation (1 — 350 m.a.s.l.) in the Overberg, Breede River Valley, Swartland and Little Karoo regions of the Western Cape Province ( Fig. 7 ). This subgenus is endemic to the Core Cape Subregion ( CCR) of the Greater Cape Floristic Region ( GCFR) sensu Manning and Goldblatt (2012).

Figures

Fig. 7. Map of the distribution of subgen.Polhillia (circles) and subgen.Roseopolhillia (triangles).