A taxonomic revision of the Cotula coronopifolia group (Asteraceae) and implications for the conservation statuses of the species *
Author
Powell, R. F.
Author
Boatwright, J. S.
Author
Magee, A. R.
text
South African Journal of Botany
2014
2014-07-31
93
105
117
http://dx.doi.org/10.1016/j.sajb.2014.03.008
journal article
10.1016/j.sajb.2014.03.008
1727-9321
10496967
5.
Cotula pusilla
Thunb., Fl. Cap.
695 (1823);
DC., Prodr. 78 (1838); Spreng., in Linn., Syst. Veg 3: 498 (1826); Harv., Harv. & Sond., Fl. Cap. 3: 178 (1865); Levyns, in Adamson & Salter, Fl. Cap. Penins. 162 (1950); Goldblatt & Manning,
Cape
Pl.: 366 (2000); Manning & Goldblatt, Pl. Gr. C.F.R. 366 (2012).
Type
:
South Africa
.
Western Cape
, (3318) ‘Swartlandiae’
Thunberg s.n. sub THUNB-UPS 20225
(UPS, lecto. image,!, designated here).
Upright, annual herb.
Stems
5–15 mm
, glabrous, herbaceous,
0.5–1.5 mm
wide.
Leaves
alternate, spreading, ±terete, entire, once-pinnate or twice-pinnate, 6.0–35 × 2.0–6.0 mm; base dilated, forming a prominent sheath around the stem, sheath 1.0–4.0 mm long; lobes linear to ovate, 0.3–2.0 × 0.1–2.0 mm, flat, leathery, light to dark green, densely to sparsely hairy, apices acute, margins entire.
Capitula
heterogamous, disciform, solitary, terminal, pedunculate, peduncles glabrous to sparsely hairy, 5.0–15.0 mm.
Involucre
hemispherical, 2.0–6.0 × 3.0–9.0 mm, 1-seriate, bracts broadly elliptic, 2.0–4.0 × 1.0–2.0 mm, glabrous, purplish, opaque, apex and margins scarious, distinctly three veined, secondary venation obscure.
Receptacle
flat, epaleate; disciform pedicels linear, 0.15–1.0 mm at anthesis, uniform, pedicel attaching to floret apically.
Disciform
fl
orets
female, ca.4 to 6, in single outer series, corolla absent, style
0.45–0.6 mm
, ovary marginally winged, with dense terete hairs on inner face.
Disc
fl
orets
bisexual, ca. 20 to 40, corolla
1.2–1.5 mm
long, whitish, oblong, tube draped basally over ovary apex, longitudinal resin canals sometimes present, limb same width as tube, 4 lobed; lobes triangular, upright to spreading, dorsally tuburculate, glandular; anthers
0.5–1.2 mm
long (including apical appendages), ecaudate, apical appendages ovate, acute; style terete with thickened base; branches truncate, papillate apically-dorsally; ovary marginally winged, dense terete hairs on inner face.
Cypselas
heteromorphic; disciform cypselas ovoid, ca. 1.7 ×
1.4 mm
, marginally winged, ±equal to width of ovary, base cordate, inner face with dense terete hairs; disc cypselas ovoid, ca. 1.2 × 0.6, marginally winged, wing width equal to ovary, with dense terete hairs.
Fig. 8.
Known geographical distribution of
Cotula vulgaris
.
Diagnostic characters
Cotula pusilla
may be readily confused with the southern populations of
C. bipinnata
with which it shares the white florets (
Fig. 1.I and K
), but can be distinguished by the broadly elliptic bracts (oblong in
C. bipinnata
), the marginally winged disc ovaries and the dense terete hairs on the inner face (
Fig. 4.E
) of both the disciform and disc ovaries (marginally ribbed and glabrous in
C. bipinnata
).
Distribution, ecology and conservation status
Cotula pusilla
is a widespread but localised habitat specialist occurring from Clanwilliam along the West Coast to the
Cape
Flats and Caledon (
Fig. 9
). It is found on the margins of seasonal saline pools in sandy coastal areas and as a result of agricultural expansion, the remaining subpopulations are largely confined to isolated fragments among crop fields. The conservation status of the species has been upgraded to VU B2ab(i,ii,iii,iv,v) and it is threatened by further habitat loss due to agricultural and urban expansion (
Powell et al., 2013e
).
Additional specimens examined
Fig. 9.
Known geographical distribution of
Cotula pusilla
.
South Africa
.
WESTERN CAPE
:
3217 (Vredenburg):
West Coast, Vredenburg, at road to Jacobsbaai (–DD),
Mucina & Jakubowsky 040806/21
(NBG).
3218 (Clanwilliam):
Zeekoei Vlei (–BA),
Schlechter 8582
(BOL); West Coast, Sandveld, road Velddrif to Piketberg, Tasaars Kuil Farm (–CD),
Mucina & Jakubowsky 040806/31
(NBG).
3318 (
Cape
Town):
West Coast, Darling, road between Malmesbury and Darling, near Wylands (–AD),
Mucina & Jakubowsky 040806/04A
(NBG); Porterville (–BB),
Schlechter 4883
(BOL); Green Point,
Cape
Town (–CD),
Thode 585
(NBG),
Ecklon & Zeyher 38779
(SAM); Claremont (–CD),
Schlechter 1066
(BOL); Three Anchor Bay (–CD);
Wolley 7253
(BOL), Robben Island (–CD),
R.S.A. s.n.
(BOL); Intaka Island (–CD),
Magee & Powell 1029
(NBG).
3321 (Ladismith):
Muiskraal (–CC),
Bolus 11320
(BOL).
3419 (Caledon):
Caledon,
1 km
South of Caledon, just east of rifle range and cemetery (–AB),
Helme 2332
(NBG); Overberg region, Fairfield farm, stop 3 (–BD),
Walton 462
(NBG).