A Taxonomic Revision of Chamaecrista (Caesalpinioideae, Cassieae, Cassiinae) in Southern Africa
Author
Musandiwa, Liada
Department of Biodiversity and Conservation Biology, University of theWestern Cape, Private Bag X 17, Bellville, 7535, South Africa
Author
Magee, Anthony R.
Compton Herbarium, South Africa National Biodiversity Institute, Kirstenbosch Research Centre, Private Bag X 7, Claremont, 7735, Cape Town, South Africa
Author
Boatwright, James S.
Department of Biodiversity and Conservation Biology, University of theWestern Cape, Private Bag X 17, Bellville, 7535, South Africa
jboatwright@uwc.ac.za
text
Systematic Botany
2022
Basel, Switzerland
2022-12-12
47
4
992
1011
http://dx.doi.org/10.1600/036364422x16674053033831
journal article
57370
10.1600/036364422x16674053033831
aca4cc44-7970-4214-8100-97fa3c87eeb6
8117056
4.
CHAMAECRISTA
COMOSA
E.Mey.
,
Comm. Pl. Afr. Austr. 1: 160 (1836)
;
Brummitt in Fl.
Zambesiaca 3(2): 142 (2007)
.
Cassia comosa
(E.Mey.) Vogel
, Syn. Gen. Cassiae 65. (1837);
Ghesquiere in
Bull. Jard. Bot. 9: 153 (1932)
; Steyaert in Bull. Jard. Bot. Brux. 20: 251 (1950); Brenan in F.T.E.A Legum.- Caesalp.: 89 (1967);
Gordon-Gray in
F.S.A. 16(2): 96 (1977)
.
TYPE
:
SOUTH
AFRICA
.
KwaZulu-Natal Province
,
Port Edward
,
500 m
from the sea opposite Hills
,
Grobbelaar
1534
(
neotype
:
PRE
!, designated here).
Note: The original Drege collection (South Africa,
Eastern Cape
, between Umzimvubu River [Omsamwubo] and Umsikaba River [Omsamcaba],
Drege
(?
B
)) cited by Meyer could not be located as most of his collections housed at B are presumably largely destroyed, so we here designate a collection of Grobbelaar as
neotype
as it is the most complete with mature flowers and fruits.
Perennial herbs, to
0.6 m
high. Stems erect, simple or sub-simple, glabrous to pubescent or densely covered with whitish to yellowish spreading hairs, arising from a woody rootstock. Leaves paripinnate, 20–150 ×
10–25 mm
, oblong to linear oblong, slightly tapering distally; stipules 5–15 ×
1–4 mm
, narrowly triangular, base oblique, apex acuminate, margin ciliate; extrafloral nectaries at or below the top of petiole, 1.2–6.0 × 0.4–4.0 mm, sessile, elliptic, depressed in the middle, often with dark centre; rachis channelled, channel margin ciliate. Leaflets (5)11–36-jugate, 4–17 ×
2–5 mm
, oblong, base oblique, apex rounded to obtuse, margin hairy. Inflorescence supra-axillary, 2–6 flowered; flowers 6–17 ×
7–20 mm
; bracts 3–4(5) mm long, base oblique, apex acuminate; bracteoles 2, glabrous, towards top of pedicels. Pedicels glabrous or with spreading hairs, at flowering
10–26 mm
long, at fruiting
15–27 mm
long. Sepals 5, ovate, 6–12 ×
3–5 mm
, with spreading hairs on the outer surface. Petals 5, obovate, 7–15 ×
4–8 mm
, bright yellow. Stamens 9, straight or slightly curved, anthers in two series, (5)6 medium ±
5 mm
long, 3(4) others often the largest, up to
9 mm
long, filaments very short ±
1 mm
long. Ovary ±
10 mm
long, densely covered with white hairs, style glabrous, slightly curved. Pods 33–65 ×
3–7 mm
, spreading pubescent, straight, flattened. Seeds 3–5 ×
1–3 mm
, rhomboid, flattened, light brown to blackish, margin often with a thin line.
Diagnostic Characters
—
Chamaecrista comosa
is one of the most easily recognisable species of
Chamaecrista
in southern Africa. It shares large flowers with
C. capensis
but is readily distinguished by the long leaves, up to
150 mm
(to
50 mm
long in
C. capensis
), with leaflets
2–5 mm
wide (
1–3 mm
wide in
C. capensis
) and large, sessile extrafloral nectaries, 1.2–6.0 × 0.4–4.0 mm, depressed in the middle or sunken in on the rachis (circular, concave, sub-sessile or attached with short stalk in
C. capensis
).
Note
—
Meyer (1836)
described
Chamaecrista comosa
for its large, sessile extrafloral nectaries, large leaves bearing broad leaflets, and large flowers. In his treatment of the African and Asian species of
Chamaecrista
Steyaert (1950)
recognised two varieties (viz.
Chamaecrista comosa
var.
capriconia
and
Chamaecrista comosa
var.
lanata
).
Chamaecrista comosa
var.
lanata
was established based on its lanate indumentum and
C
.
comosa
var.
capriconia
for its smaller morphology.
Gordon-Gray and Schorn (1975)
later included
Chamaecrista comosa
var.
lanata
within
C. comosa
var.
comosa,
a decision that is supported by the present study. Following examination of available herbarium material, two varieties were recognised; one that occurs in coastal areas and one that occurs in drier areas. Based on field studies and examination of herbarium material
C
.
comosa
var.
capriconia
and
C. comosa
var.
comosa
need to be raised to subspecific level on the basis of different habitat preferences (
C. comosa
var.
comosa
is restricted to open grassland with high water table on granite derived soil or sand, and
C
.
comosa
var.
capriconia
in grassland in dried areas usually on sandy soil (
Gordon-Gray and Schorn 1975
)), distribution patterns (i.e.
C
.
comosa
var.
comosa
is restricted to the coastal areas of KwaZulu-Natal and Eastern Cape, while
C
.
comosa
var.
capriconia
has a more northern distribution extending beyond the region to
Zimbabwe
), and morphological differences (
C
.
comosa
var.
capriconia
is smaller in its general morphology).
Two subspecies are recognised: