Acanthopsis carduifolia, , Drege, 1843

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 : 117-119

6. Acanthopsis carduifolia (L.f.) Schinz (1890: 200); Clarke (1901: 33); Snijman (2013: 163) ( Figs. 1 , 3F & 9 )

Basionym:— Acanthus carduifolius Linnaeus (1782: 294) . Blepharacanthus carduifolius (L.f.) Nees in Steudel (1840: 209). Acanthodium carduifolium (L.f.) Nees von Esenbeck (1847: 278), pro parte. Blepharis carduifolia (L.f.) Anderson (1864: 35), pro parte. “ Acanthus carduifolius Thunb. ” in Drège (1837: 2), nom nud.

Type: — SOUTH AFRICA. Northern Cape: Cap. bona Spei. Cape of Good Hope, Crescit in rupibus Hantum [Hantam], fide Thunberg (1823)], Thunberg 83 (lectotype LINN 816.2! designated here).

Perennial, compact subshrub, (5–)7–10(–12) cm tall with very short internodes. Leaves sessile, base petiole-like with spines 3–5 mm long; lamina oblanceolate, 35–45(–70) × 4–6(–10) mm, puberulent to hirsute with strigose to spreading short hairs, also with subsessile glandular hairs; apex acute, base attenuate, margin undulate, coarsely dentate-spinose, spines rigid, 2–4 mm long, yellowish, often reddish towards base. Inflorescences semi-dense, cylindrical, subsessile to shortly pedunculate with 3 (or 4) pairs of peduncular bracts at the base, (25–)40–60(–90) mm long, 6–9(–10) mm in diameter; peduncle up to 20 mm long, pubescent with spreading hairs. Bracts obovate to wedge-shaped, 17–23 mm long (including spines), lamina 7–9(–11) mm long, base attenuate; hirsute to pubescent with deflexed or spreading short hairs and short to subsessile glandular hairs abaxially, silky-hairy adaxially, lamina rarely villose with long spreading, antrorse hairs (see Pearson 3346, BOL); middle and upper bracts ending in 5 primary spines; central primary spine usually simple or occasionally with 1 pair of very short, marginal secondary spines; lateral primary spines often with 1 basal secondary spine on side facing central primary spine; spines often porrect in flower, porrect to recurved in fruit. Bracteoles linear, 7–8 mm long, silky-hairy, especially towards base. Calyx with dorsal sepal ovate, apiculate, 11–12 mm long, silky-hairy especially adaxially, 7(–9)-veined; ventral sepal ovate, 10–11 mm long, 5–7-veined, silky-hairy especially adaxially; lateral sepals 7 mm long, silky-hairy especially adaxially, often with fringe of long, silky hairs around margin, 3-veined from base. Corolla white or cream to lilac with purple veins and white or cream throat, 20–25(–27) × 8–10(–12) mm, tube 5–8(–10) mm long, central lobe wider than long or equal, constricted at the base, emarginate. Filaments 6–7 mm long, glandular; anthers beige to orange, 3 mm long. Style with patch of glandular hairs at the base. Capsules 8–9 × 3 mm. Seed 3 × 3 mm.

Etymology: —The specific epithet carduifolia refers to its leaves resembling those of the genus Carduus Linneaus (1753: 820) .

Distribution, ecology and phenology: — Acanthopsis carduifolia is near-endemic to the Hantam-Roggeveld Centre of Endemism ( Van Wyk & Smith 2001) and is known from a few locations in an area to the north-west of Calvinia (Northern Cape) ( Fig. 1 ). This distribution falls within the Succulent Karoo Biome ( Rutherford & Westfall 1994, Low & Rebelo 1996, Mucina & Rutherford 2006) in the Trans-Escarpment Succulent Karoo Bioregion ( Mucina & Rutherford 2006) where it receives predominantly winter rains with an average of ± 200 mm per year. This species prefers loamy soils derived from Ecca shale but is also found on sandy soils to the north of the distribution range, and mainly grows on hill slopes at elevations between 550 and 960 m. Specimens with flowers were collected from September to November.

Conservation status: —A range-restricted (EOO 2614 km ²) and rarely recorded species that is likely to be under-sampled, as it occurs in a botanically poorly explored area. There are no severe threats to this species and subpopulations are large, therefore it is not suspected to be in danger of extinction. Field observations indicate that this species is fairly abundant even in heavily overgrazed areas, suggesting that it is likely to be resilient to disturbance and hence is categorised as Least Concern according to the IUCN Red List Category and Criteria ( IUCN 2012) (L. von Staden, pers. comm.).

Additional specimens examined: — SOUTH AFRICA. Northern Cape: Upper Namaqualand and Karroo, Alewyn’s fontein, (3018 BC), 22 December 1908, Pearson 3318 ( BOL) ; Little Namaqualand. In sand at foot of kopje – Alewyn’s Fontein , 22 December 1908, Pearson 3346 ( BOL) ; Namaqualand District. South of Alewynsfontein, on koppie W of road to Platbakkies , 961 m, 29 September 2015, Steyn 2106 ( PRE) ; Namaqualand and Bushmanland, about 10 miles [16 km] north east of Klipplaat , (3019 CC), December 1908, Pearson 3308 ( BOL, SAM in NBG) ; 40 km NW of Calvinia on Naresie road, 640 m, (3119 AD), December 2013, Scholtz s.n. ( PRE) ; Calvinia District. NW of Calvinia on Gannabos / Naresie road, 549 m, (3119 AD), 30 September 2015, Steyn 2108 ( PRE) ; North of Calvinia on the Toren road, 960 m, (3119 BC), 22 October 2014, Koekemoer 4620 ( PRE) ; Calvinia District . N of Calvinia ; 23.5 km on Loeriesfontein road - turn right at Toren turn-off, (3119 BC), 31 August 2012, Steyn 1894 ( PRE) ; Calvinia District. On Toren road, 956 m, (3119 BC), 30 September 2015, Steyn 2109 ( PRE) .

Without precise locality: Masson s.n. (BM); Thunberg s.n. (P), Thunberg 84 (SBT), Thunberg s.n. (UPS).

Notes: — Acanthopsis carduifolia differs from A. villosa H.M.Steyn in Steyn & Van Wyk (2015: 14) in having semi-dense inflorescences with hirsute bracts ending with a simple central primary spine (not dense inflorescences with densely villose bracts ending with a compound central primary spine), and the white-cream to lilac flowers with purple veins (not purple flowers with darker veins) and strigose leaves (not densely villose leaves). Acanthopsis carduifolia can be distinguished from A. glabra by the smaller flowers, the obovate to wedge-shaped (not oblong to obovate) bracts with an attenuate (not cuneate) base, the bract spines usually being longer than the bract lamina (not occasionally longer than lamina), and the much shorter inflorescences ((25–)40–60(–90) mm long) (not (50–)70– 140(–250) mm long).

The earliest known herbarium specimen of a member of what is at present classified as Acanthopsis , was probably “ Acanthus carduifolius Thunberg ” collected by Carl Pehr (Peter) Thunberg in the Hantam (region surrounding the present-day town of Calvinia in the Northern Cape) during November 1774. A specimen housed in Paris (Thunberg (?) s.n.) (P04426164), is labelled “ Acanthus carduifolius Thunberg ” in Thunberg’s handwriting. The name Acanthus carduifolius was validly published by the younger Linnaeus (1782: 294) based on a collection claimed to be collected by Anders Sparrman from “Cap. bonae Spei” [Cape of Good Hope, South Africa]. What is most probably the sheet used by the younger Linnaeus (Linnean Herbarium: LINN 816.2) gives no information on the collector or locality, only the number 83 and the name Acanthus acaulis in the older Linnaeus’ hand. In addition, the epithet “acaulis ” has been deleted and replaced with “ carduifolia ”. It is inferred that this collection was collected by Thunberg as the first known botanical exploration into the Hantam region was done by Thunberg and Francis Masson in 1774 when they travelled to the Roggeveld via the Hantam ( Forbes 1986, Glen & Germishuizen 2010). Both Thunberg and Masson collected Acanthus (= Acanthopsis ) specimens on this trip: Thunberg s.n. (P04426164), Thunberg s.n. (UPS V-14645), Thunberg 83 (LINN 816.2), Thunberg 84 (SBT12606) and Masson s.n. (BM000810289, BM000810290). These specimens could only have been from the Hantam region as no other member of Acanthopsis are known to occur anywhere else along the route they followed ( Fig. 1 ).

In 1837 Jean François (Johann Franz) Drège listed the name Acanthus carduifolius ( Drège 1837: 2) . Meyer in Drège (1843: 69, 91) recorded it as being collected twice by Drège during October 1830 at “Kaus (Gebirge bei Goedemanskraal, Rustbank und Kookfontein), 3000–4000 ft ” and November 1830 at “Bei Ezelsfontein und am Roodeberg, 3500–4000 ft ” respectively. The “Alphabetisches Verzeichniss” [Alphabetical List] ( Drège 1843: 161), however, indicates that two different forms (not the typical form sensu Thunberg ) were collected, namely [variety] ά (“Bei Ezelsfontein und am Roodeberg”) and [variety] ss (“Kaus (Gebirge bei Goedemanskraal, Rustbank und Kookfontein”). A sheet in the Paris Herbarium (Drège 2431) (P04426162) is labelled with “ Acanthus carduifolius Th. ά spica glabriuscula EM.” [E.Meyer] in Meyer’s handwriting. This form was listed as being collected only once by Drège (1843) and possible duplicate sheets of Drège 2431 are found in Paris and Stockholm (Drège s.n.) (P04426165) and (Drège s.n.) (S09-4229, S11-26492), labelled by Meyer, Drège and Meyer respectively. One Stockholm sheet (S11-26492) was labelled with an incorrect locality as this form (ά spica glabriuscula) was collected at Ezelsfontein and Roodeberg ( Drège 1843) and not at Kaus as indicated on the specimen label. These sheets are now considered to be A. scullyi . Only one sheet of Drège’s Acanthus carduifolius Th. ss spica villosa EM. [E.Meyer] could be traced to the Paris Herbarium (Drège 2433) (P04426163) and was labelled by Meyer. The latter name (based on the Drège specimen) is now regarded as a synonym of Acanthopsis villos a H.M.Steyn in Steyn & Van Wyk (2015: 14).

Figures

FIGURE 1. Known distribution of A. glabra (○), A. scullyi (▲), A. nitida (□), A. glandulopalmata (■) A. insueta (Δ) and A. carduifolia (●). Thunberg’s route (1774) indicated in red. (for explanation see Notes under taxonomic treatment of A. carduifolia)

FIGURE 3. Comparison of floral parts, associated bracts and bracteoles (from left to right): bracts (2), bracteoles (2), calyx (4 sepals: dorsal, ventral and 2 lateral ones) and corolla with anthers.A. A. glabra, B. A. scullyi, C. A. nitida, D. A. glandulopalmata, E. A. insueta, F. A. carduifolia. Note: the bract on the left is from lower down in the same inflorescence. Scale bar = 10 mm. Vouchers:A = Steyn 1893 (PRE), B = Steyn 1911 (PRE), C = Steyn 1884 (PRE), D = Steyn 1890 (PRE), E = Steyn 1805 (PRE), F = Koekemoer 4620 (PRE).

FIGURE 9. Acanthopsis carduifolia. A & B. Habit. C & D. Leaf indumentum (abaxial). E & F. E &F. Bract. G. Calyx. H. Corolla (lobes cream to lilac; throat cream or white). I. Glandular hairs at base of style. J. Capsule. K. Seed. Vouchers: C–I = Koekemoer 4620 (PRE), J = Steyn 2106 (PRE), K = Steyn 2108 (PRE). Photographed by: M. Koekemoer (A) and H.M. Steyn (B–K).