Achyranthemum N. G. Bergh, a new genus segregated from Syncarpha DC. (Asteraceae, Gnaphalieae) *
Author
Bergh, N. G.
Author
Manning, J. C.
text
South African Journal of Botany
2019
2019-09-30
125
434
456
http://dx.doi.org/10.1016/j.sajb.2019.08.015
journal article
10.1016/j.sajb.2019.08.015
1727-9321
10496693
4.3.
Achyranthemum recurvatum
(L.f.) N.G.Bergh,
comb. nov.
Xeranthemum recurvatum
L.f.,
Suppl. Pl.: 366 (1782)
.
Helichrysum
(as ‘Elichrysum’)
recurvatum
(L.f.) Willd., Sp. Pl., ed. 4, 3(3): 1906 (1803).
Syncarpha recurvata
(L.f.)
B.Nord.,
Comp. Newsl. 17: 6 (1989)
.
Type:
South Africa
,
Cape of Good Hope
, without date or locality, Herb. Bäck (
LINN
990.25,
holo
.–digital image!)
Low, tangled shrublet to about
0.4 m
, branches often trailing, decumbent, forming loose mats, slender, woody, leafless below; young branches densely white-felted, glabrescent.
Leaves
closely alternate-decussate, sessile and slightly decurrent, stiff and recurved, strongly conduplicate, linear to lanceolate, 10–33 × 3.0–
4.5 mm
, pungent, apical mucro ±
1.2 mm
long; firm-textured, abaxial surface with very long (
2–3 mm
or longer) stout silvery-white arachnoid hairs that cohere to form a a thick, longitudinally oriented irregularly reticulating lattice-like sheath, ends of hairs projecting from margins in silky clumps, adaxial surface glabrous or sparsely arachnoid.
Capitula
terminal, solitary, depressed-globose,
12–14 mm
long and (10–)12–15(–18) mm wide, usually distinctly pedunculate, peduncles robust, straight,
5–35 mm
long, densely pale-grey felted and bearing one or a few widely spaced, narrow, involucre-like bracteoles; involucral bracts ±70, in ±12 series, outer erect, lanceolate, acute, 7 ×
2 mm
, stereome small, greenish, bearing white hairs, lamina smooth and dirty-white, middle series erect, subspathulate with acute to obtuse apex, 11 ×
3 mm
, stereome as in outer bracts, lamina white tinged rose-pink, innermost series erect to cucculate, obovate with obtuse apex, 5–7 ×
1.5 mm
, white tinged pink.
Florets
±60 to 75, yellow, 5.5 ×
0.7 mm
, lobes erect; anther apical appendage caudiculate.
Cypselae
ovoid, 3.0 ×
1.5 mm
, pale brown.
Pappus
bristles nude at the base where they are united into a smooth ring, otherwise barbellate, apices slender, acute.
Flowering time:
mainly October–November, but plants can be found in flower in April and other months (
Fig. 5
).
Distribution and ecology:
Highly localised endemic of the
Eastern Cape
from Hankey to Alexandria, restricted to low-lying areas (from sea level up to
200 m
altitude in the Bontveld, a highly restricted vegetation
type
that covers only
500 km
2
and consists of a mosaic of bushclumps and grassveld. Within the Bontveld,
A. recurvatum
is confined to shallow calcareous sands on calcrete ridges.
Diagnosis:
A highly distinctive species, the only one in the genus with strictly solitary capitula. The relatively small, stiff leaves are strongly recurved, with the adaxial surface ±glabrous while the abaxial surface is covered with long matted hairs, clumps of these hairs projecting from the margins like soft, curled spines. The indumentum appears as a surface layer of silvery tissue that has been reticulately disrupted, and due to clumping the individual hairs are not discernable. In this feature, the leaf indumentum in
A. recurvatum
is similar to that in
A.paniculatum
and
A. mucronatum
.
This is the most morphologically uniform species in the genus. The solitary capitula, usually on long straight peduncles, with pink-tinged involucres, together with the small, recurved leaves, are diagnostic.
Achyranthemum recurvatum
might be confused with forms of
A. sordescens
,
A. af
fi
ne
and
A. argenteum
with recurved leaves, but can be distinguished by the leaf indumentum and capitulum characters (see under species descriptions).
Conservation status:
This species is listed as Endangered (www. redlist.sanbi.org accessed
August 2018
). At the time of assessment, eight severely fragmented subpopulations were thought to remain, and these were in decline due to cement mining, urban expansion and alien plant invasion. Exploitation as everlasting cut flowers may also pose a threat in populations that are easily accessible. The plant is rarely collected, being confined to a rare habitat that has come under threat due to habitat transformation, such as the development of the Coega Industrial Zone. A study by
Swart (2006)
indicated that only four populations remained. Conservation through relocation is the focus of ongoing studies by E. E.Campbell and students at the Nelson Mandela Metropolitan University.
History:
Xeranthemum recurvatum
was described by Linnaeus f. in 1781 based on an unlocalised specimen in the collection of Abraham Bäck (1713–1795), Swedish physician and close friend of Carl Linnaeus snr. The identity of the species is clear-cut and there are no synonyms.
Additional specimens seen:
South Africa
.
Eastern Cape
. –3324 (
Steytlerville
):
Hankey
, near
Humansdorp
, (–
DD
)
,
3 Oct 1966
,
Bayliss
3605
(
NBG
)
. –
3325 (
Port Elizabeth
):
Alexandria
,
Kaba Valley
, (–
CB
)
,
23 July 1954
,
Archibald
5504
(
PRE
)
;
Uitenhage District
, by the
Zwartkop River
, (–
CB
)
,
Nov
,
Drège
416
(
BOL
,
SAM
)
;
Uitenhage
, (–
CD
)
,
Ecklon
&
Zeyher
418
(
SAM
)
;
Cape
of
Good Hope
,
Uitenhage
, (–
CD
)
,
Ecklon
&
Zeyher
PRE 11,967
(
PRE
)
;
Blue Horizon Bay
, (–
CD
)
,
21 May 2002
,
Potgieter
FP00919
(
PRE
)
;
Grahamstown
, Maitland
River Mouth
, (–
CD
)
,
11 Sept. 1982
,
Van Jaarsveld
6847C
(
NBG
)
;
Maitlands Forest Reserve
, next to footpath on
De Stades
route, (–
CD
)
,
7 Nov 2009
,
Weatherall-Thomas
CR15098/PEG18
(
NBG
)
;
road side of fence,
10 km
from turnoff from
Addo
to
Centilivers
, (–
DA
)
,
12 March 2011
,
Haiden
5
(
NBG
)
;
10 km
from turnoff from
Addo
to
Centilevers
, roadside of fence, (–
DA
)
,
12 June 2011
,
Haiden
6
(
NBG
)
;
between Centlivres and Addo
:
Windmolen Farm
, (–
DA
)
,
29 Sept. 1984
,
Stirton
10,850
(
PRE
)
;
Lime Hill
on rd. to
Addo
, ±
500 km
2
around
Port Elizabeth
, as far as
Alexandra
; on road
Zwartkops
to
Addo
,
5 mi
N of De Rust
, (–
DA
)
,
19 Nov 1977
,
Anderson
4
(
BOL
)
;
Uitenhage Div.
, along rd. from
Addo
to
Port Elizabeth
, (–
DA
)
30 Dec 1965
,
Troughton
223
(
PRE
)
;
Coega
,
7 M.
ENE of Coega
, (–
DC
)
,
4 March 1948
,
Acocks
14,054
(
PRE
)
;
3.5 MI NE of
Coega.
(–
DC
)
,
17 March 1954
,
Acocks
17,621
(
PRE
)
;
Coega
,
2.4 miles
from
Coega on Grahamstown
rd, (–
DC
)
,
17 March 1954
,
Comins
758
(
PRE
)
;
Algoa Bay
,
St. George’
s
Strand
, (–
DC
)
,
20 Nov 1932
,
Long
840
(
PRE
)
;
near
Humansdorp
,
Hankey
, (–
DD
)
,
3 Oct 1966
,
Bayliss
3605
(
NBG
)
;
Distr. Uitenhague
, by the
Zwartkop river
, amongst shrubs on the
Karoolike
hills, (–
CD
)
,
unknown
(
BOL 103120
)
; –
3326 (
Port Elizabeth
):
Port Elizabeth
,
35 miles
NE of Coega
, (–
CA
)
,
17 March 1954
,
Acocks
17,621
(
PRE
)
;
Alexandria
,
Kaba Valley
, (–
CB
)
,
23 July 1954
,
Archibald
5504
(
PRE
)
. Without precise locality:
Formosa
,
Lauterwater
,
Jan 1940
,
Stokoe
s.n.
(
SAM 54700
)
;
1856,
de
Castelnau
136
(
PRE
)
;
Ecklon
&
Zeyher
416
(
BOL
,
PRE
)
;
Zeyher
s.n.
(
SAM 16339
)
;
Zeyher
PRE 43,776
(
PRE
)
;
Van Staden’
s
River
,
Uitenhague
,
Drège
s.n.
(
PRE 204291
)
; South
A.recurvatum
Fig. 5.
Achyranthemum recurvatum
. A. Habit. B. Leaves. C. Capitulum. D. Leaf indumentum (
Haiden 6
, NBG). E. Distribution. All photographs N.G. Bergh.
Africa,
Drège s.n.
(BOL);
Ecklon & Zeyher s.n.
(PRE 204292);
Zeyher s.n.
(PRE 204290).