Acanthopsis, , Clarke, 1901

Steyn, Hester M. & Van Wyk, Abraham E., 2016, Taxonomic notes on the shrublet species of Acanthopsis (Acanthaceae, tribe Acantheae), with two new species from South Africa, Phytotaxa 244 (2), pp. 145-160 : 148

Key to the shrublet species of Acanthopsis (species are also compared in Table 1)

1. Inflorescences <30(–35) mm long; middle to upper bracts with central primary spine spatulate (Namaqualand, Northern Cape).... ................................................................................................................................................................................... 1. A. spathularis

- Inflorescences (25–)30–70(–90) mm long, middle to upper bracts with central primary spine ensiform, narrowly triangular or ovate (but never spatulate)...........................................................................................................................................................................2

2. Leaves lanceolate to linear, margin very coarsely dentate-spinose; spines rigid, 4–7 mm long, yellow; bract spines silky hairy on margins ............................................................................................................................................................................ 2. A. horrida

- Leaves lanceolate to oblanceolate, margin coarsely dentate-spinose; spines fine to rigid, 1–4 mm long, orange-brown; bract spines never silky hairy on margins..............................................................................................................................................................3

3. Middle to upper bracts ending in 5 drawn-out, narrowly triangular primary spines, corolla throat white ........................ 3. A. erosa

- Middle to upper bracts ending in 3 ovate, mucronate to spinose lobes, corolla throat lemon-yellow ......................... 4. A. dregeana