Jacobsenia hallii L.Bolus

Klak, C., Hanáček, P. & Bruyns, P. V., 2018, A recircumscription of Jacobsenia (Aizoaceae): Re-instating Drosanthemopsis, with two new quartz-endemics from Namaqualand, South Africa and sinking Knersia *, South African Journal of Botany 116 (10), pp. 67-81 : 76-77

2. Jacobsenia hallii L.Bolus ,

Notes Mesembryanthemum 3: 329 (1958). Drosanthemum jacobsenii G.D. Rowley, Natl. Cact. Succ. J. 33(1): 8 (1978).

Type: South Africa. Western Cape, Komkans (3118AA), 50 miles N of Vredendal , 3rd Sept. 1955, H. Hall sub NBG 405/54 ( BOL, holo!) .

Compact shrublets to 15 cm high, main stem in old plants procumbent, adult plants without clear distinction between long shoots and short shoots; each stem mostly developing 2 leaf-pairs per season; leaf-pairs occasionally slightly anisophyllous. Leaves often slightly curved, moderately spreading, mostly terete with upper surface flattened, lower surface slightly keeled, 30–70 mm long, 8–10 mm diam.; epidermis with large, ± circular bladder cells with a single central hair-like protrusion. Flowers emerging from the connate portion of the 2nd leaf-pair of the season, 80–85 mm diam., pedicels 10–20 mm long; sepals 6, two outer ones opposite, the remaining spirally arranged; petals white or light yellow; filaments deep yellow. Fruit shape of capsule seen from above 6-angled, 8–17 mm diam., locules mostly 6, rarely 5, 7 or 8.

Ecology and distribution: The species is restricted to a small area north of Vredendal, South Africa.Here it forms very localized, dense colonies on loamy strongly saline sand, with a cover of large quartz gravel. Flowering time is from August to September. ( Fig. 7 ).

Diagnostic characters: Jacobsenia hallii has a compact habit, lacking the characteristic long shoots found in J. kolbei . The epidermis of the leaves is covered with large bladder-cells, which each have a single central hair-like protrusion.

Conservation status: Jacobsenia hallii is a rare species, known from only two localities and has been listed by Raimondo (2009) as vulnerable (VU).

Additional specimens examined

South Africa. WESTERN CAPE: 3117 (Lepelfontein): NE of Brand se Baai , farm Kerskloof (-BB), Klak 2318 (BOL) ; 3118 (Vanrhynsdorp): NW of Komkans (−AA), Bruyns 6142 (BOL) ; Komkans (− AA), H. Hall sub NBG 405 /54 (BOL) ; NW of Komkans farm house (− AA), Klak 2293 (BOL) ; Komkans , H. Hall 2569 (NBG) .

Figures

Fig. 7. Distribution of Jacobsenia. J.kolbei and J.hallii, with Knersvlakte phytochorion indicated (red hashes).