Cotula duckittiae (L.Bolus) Levyns

Jakoet, A., Mucina, L. & Magee, A. R., 2019, The pseudo-radiate buttons: A taxonomic revision of the Cotula turbinata group (Asteraceae; Anthemideae) and the description of two new species *, South African Journal of Botany 121, pp. 282-293 : 292

6. Cotula duckittiae (L.Bolus) Levyns , in Adamson & Salter, Fl. Cape Penins. 161 (1950); Bremer & Humphries, Bull. Nat. Hist. Mus. London, Bot. 23: 159 (1993).

Cenia duckittiae L.Bolus, Ann. Bolus Herb. 4: 15 (1925).

Type: South Africa. Western Cape, Malmesbury (3318): Darling (− AD), Sep 1922, C. J. Duckitt 17,184 (BOL, holo.!; K–image!, iso.).

Annual herb, 165–580 mm. Not rooting at the nodes. Stems usually decumbent, 135–283 mm long, sparsely hairy. Leaves alternate, decreasing in length towards upper part of plant, 2- to 3-pinnatisect, 9–72 × 10–19 mm, obovate, green, petiole-like base usually present; lobes linear, 1–6 × 0.4–1.0 mm, ±terete, becoming progressively smaller towards the leaf base, usually downy, apices cuspidate to acute. Capitula heterogamous, 12–22 mm in diameter, disciform, pseudo-radiate, disc face flat to slightly concave, solitary, terminal, pedunculate; peduncles 40–192 mm long, apically swollen in fruit, swelling obconical, 5–18 × 8–15 mm, dark green, hollow. Involucre hemispherical; bracts 2- or 3-seriate; broadly ovate, 3–6 × 3–5 mm, apex obtuse to acute, hairs always present on tips, green, opaque, apex and margins scarious, brownish, 3- to 7-veined. Receptacle flat to shallowly concave. Filiform fl orets female, in single outermost series, pedicellate, corolla absent; ovary elliptic, marginally winged, slightly concave on the ventral surface, glandular; pedicels linear, 1 mm at maturity. Disc fl orets bisexual, heteromorphic, pedicellate, 4-lobed, lobes mostly triangular, ca. 0.2 mm long, florets in two outermost series with the dorsal lobe greatly enlarged to resemble a ray limb, dorsal lobe ±4 times length of other three lobes, elliptic, ca. 2–5 mm long; tube not basally draping over the ovary; limbs funnel- to bell-shaped, usually orange but sometimes canary yellow; pedicels 0.1–0.6 mm long, gradually decreasing in length towards center. Cypselae heteromorphic; those of filiform florets ovoid, 1.6–2.2 × 1.1–1.4 mm, broadly winged, wing ca. ¼ times width of the fertile portion, slightly concave on outer surface, sessile glands present; those of disc florets ovoid, 1.6 × 0.8 mm, marginal ribs prominent, sessile glands present; band of myxogentic cells on ventral surface flanking the fertile portion; resin canals absent.

Diagnostic characters: Cotula duckittiae is unique in that it has large, showy usually orange (rarely canary yellow) pseudo-radiate heads with a flat to concave disc face ( Fig.1. K–L ) and myxogenic cells flanking the fertile portion on the ventral surface of the disc cypselae ( Fig. 3. C 2 ). The enlarged dorsal lobe of the outer disc florets is significantly larger than in all the other species, ±4 times the length of the other three lobes ( Fig. 2. F ), and there are often up to two series of these modified disc florets.

Distribution and ecology: Cotula duckittiae is endemic to the West Coast where it occurs scattered from Elandsbaai to Malmesbury ( Fig. 9 ). Populations are highly localized, but locally abundant ( Fig. 1. J ). It occurs on coarse sand derived from granite. Flowers in spring (September).

Additional specimens examined: South Africa. WESTERN CAPE: 3218 (Clanwilliam): Clanwilliam, Coast S of Elandsbaai, 5.6 km N of Draaihoek Lodge (− AD) , 9 Sep 2009, Goldblatt & Porter 13,298 ( NBG) . 3318 (Cape Town ) : Farm Rondeberg 10 km SE of Darling (− AD) , 13 Sep 1989, Pool 97 ( NBG; PRE); West Coast: Rondeberg Nature Reserve (− AD) , 25 Aug 2014, Magee & Jakoet 1127 ( NBG) ; Bok Bay, Malmesbury (– CB) , 11 Sep 1937, Compton 6780 ( NBG) ; 15 Sep 1940, Kies 154 ( NBG) ; near Leerbaai, ± 2 mls North of Bokbaai (– CB) , 20 Sep 1968, Rourke 1115 ( NBG; PRE); Buffelsrivier, Malmesbury (– CB) , 18 Oct 1962, Taylor 4160 ( NBG) ; 1 km west of Pella (− DA) , 31 Aug 1977, Emdon 15 ( NBG; PRE). Precise locality unknown: Darling Flower Show , 23 Sep 1950, Maguire 447 ( NBG) .

Figures

Fig.1. Species of the Cotula turbinata group showing the main diagnostic characters.(A)The multi-nerved broad bracts found in all species in this group (from C.turbinata); (B) C.discolor; (C–D) Cotula turbinata,note the apical swelling of the peduncle;(E–H) Cotula calcicola, note the convex disc face (H) and size of the cypselae in the filiform florets (G); (I) Cotula pruinosa; (J–L) Cotula duckittiae, note the flat to concave disc face and the multiseriate pseudo-rays (K & L).

Fig.3. Cypsela variation in the Cotula turbinata group.(A) C.calcicola: (A1) cypsela of filiform floret; (A2) cypsela of disc floret;(B) C.discolor: (B1) cypsela of filiform floret; (B2) cypsela of disc floret;(C) C.duckittiae: (C1) cypsela of filiform floret;(C2) cypselaof disc floret;(D)C.perennans: (D1) cypsela of filiform floret;(D2) cypsela ofdisc floret;(E) C.pruinosa: (E1) cypsela of filiform floret;(E2) cypsela of disc floret;(F) C.turbinata: (F1) cypsela of filiform floret; (F2)cypsela of disc floret.Vouchers:(A1) & (A2) Magee & Jakoet 1138a (NBG);(B1) &(B2) Jakoet 54 (NBG);(C1) & (C2) Magee & Jakoet 1127 (NBG);(D1) Esterhuysen 33,481 (BOL);(D2) Esterhuysen 33693 (BOL) (E1) & (E2) Magee & Jakoet 1111 (NBG);(F1) & (F2) Magee & Jakoet1114 (NBG).Scale: 1 mm.

Fig. 2. Floret variation and position in the Cotula turbinata group. (A) Diagram representing the positon of the different florets in a typical capitulum, with black circles representing the filiform florets, diamond shape representing the pseudo-ray florets and the white circles representing the disc florets; (B) typical filiform floret from C.pruinosa; (C) typical disc floret from C. duckittiae; (D-I) pseudo-ray florets in C. calcicola (D), C. discolor (E), C. duckittiae (F), C. perennans (G), C. pruinosa (H), and C. turbinata (I). Vouchers: (B) Jakoet & Magee 1111 (NBG); (C) Magee & Jakoet 1127 (NBG); (D) Magee & Jakoet 1138a (NBG); (E) Jakoet 54 (NBG); (F) Magee & Jakoet 1127 (NBG); (G) Esterhuysen 35120 (BOL); (H) Jakoet & Magee 1111 (NBG); (I) Magee & Jakoet 1114 (NBG). Scale: 1 mm.

Fig. 9. Known geographical distribution of Cotula duckittiae.