Acanthopsis, Harvey, 1842

Steyn, Hester M. & Van Wyk, Abraham E., 2017, Taxonomic notes on Acanthopsis (Acanthaceae, tribe Acantheae): the group with semi-dense spikes and 5 - fid bracts, Phytotaxa 324 (2), pp. 101-121 : 104

Key to the species of Acanthopsis in the semi-dense spike group with 5-fid bracts:

1. Leaves strigose to villose; inflorescences usually> 70 mm long; floral bracts lax (overlap <30%) ( Fig. 2 ); inflorescence axis often exposed; bract spines often shorter than bract lamina........................................................................................................................2

- Leaves puberulent, strigose or with appressed hairs; inflorescences usually <70 mm long; floral bracts semi-dense (overlap 30– 60%) ( Fig. 2 ); inflorescence axis rarely exposed; bract spines usually as long as or longer than bract lamina ................................3

2. Leaves strigose; floral bracts usually with simple central primary spine, spines usually ensiform; bracts hirsute with deflexed to appressed short hairs ( Kamiesberg area , Northern & Western Cape) ...............................................................................1. A. glabra

- Leaves villose; floral bracts nearly always with compound central primary spine, spines usually triangular; bracts pubescent or villose with antrorse silky hairs (Steinkopf to Kamiesberg, Northern Cape)....................................................................2. A. scullyi

3. Leaves puberulent, glossy; bracts puberulent to glabrous; calyx glabrous ( Anenous Pass area , Northern Cape).............3. A. nitida

- Leaves with indumentum of appressed, strigose or spreading hairs; bracts hirsute (often pubescent to villose); calyx hirsute to pubescent ............................................................................................................................................................................................4

4. Bracts with relatively long (up to 0.25 mm), spreading glandular hairs; primary spines winged (lanceolate), nearly always simple; corolla relatively large (28–32 mm long), tube 9–10 mm long, (Richtersveld, Northern Cape) .....................4. A. glandulopalmata

- Bracts with short (usually <0.16 mm), deflexed to spreading eglandular hairs (rarely pubescent to villose); primary spines narrow (ensiform) to narrowly winged, central primary spine often simple, lateral ones usually with basal secondary spine on the side facing the central primary spine; corolla smaller (20–25 mm long), tube 5–9 mm long........................................................................5

5. Plants grey due to appressed, densely packed short hairs on leaves; middle to upper bracts ending in (3–)5 primary spines, upper bracts very often 3-fid; secondary spines often longer than primary spines; corolla throat lemon-yellow (Richtersveld, Northern Cape).................................................................................................................................................................................5. A. insueta

- Plants pubescent with strigose short, white hairs on leaves; middle to upper bracts ending in 5 primary spines; secondary spines (if present) always shorter than primary spines; corolla throat cream or white (Hantam, Northern Cape)....................6. A. carduifolia

Figures

FIGURE 2. Types of inflorescences found in Acanthopsis based on density of individual flowers and their bracts. A. dense (>60% bract lamina overlap), B. semi-dense (30–60% bract lamina overlap), C. semi-dense (<30% bract lamina overlap). Scale bar = 10 mm. Artist: Daleen Roodt.