Chamaecrista falcata, Musandiwa & Boatwr., Phytotaxa

Musandiwa, Liada, Magee, Anthony R. & Boatwright, James S., 2022, A Taxonomic Revision of Chamaecrista (Caesalpinioideae, Cassieae, Cassiinae) in Southern Africa, Systematic Botany (Basel, Switzerland) 47 (4), pp. 992-1011 : 1002

5. CHAMAECRISTA FALCATA Musandiwa & Boatwr. , Phytotaxa 413(4): 275 (2019).

TYPE: SOUTH AFRICA. KwaZulu-Natal Province, Hlabisa (2832): Hluhluwe-Imfolizi Park [Umfolozi Game Reserve] , (–AA), 11 Nov 1954, Ward 2439 (holotype: PRE!, isotype: NU!).

Perennial herbs, ± 0.3 m tall. Stems decumbent or prostrate, multiple branching from woody rootstock, erect to semi-erect covered with short curved and long patent hairs. Leaves paripinnate, 10–50 × 10–25 mm, tapering distally; stipules, 3–9 mm long, triangular, base oblique, apex acuminate, margin with long hairs; rachis channelled; rachis extension 2–4 mm long; extrafloral nectaries in upper half of the petiole or slightly above the middle, sometimes on rachis of lower leaflets, with a distinct stalk 1.0– 1.5 mm long, dark brown, 0.02–0.03 mm in diameter, concave at the top. Leaflets 4–15-jugate, 3–15 × 1.5–4.0 mm, falcate, base oblique, apex apiculate, top surface with long scattered hairs, bottom surface glabrous, margin with curved or straight hairs; midrib strongly excentric towards anticous margin. Inflorescences axillary; 1–2 flowered; bract hairy, base oblique, apex acuminate, ± 3 mm long; bracteoles 2, narrowly triangular, base oblique, apex acuminate, with long patent hairs, above the upper half of the pedicel or towards top of pedicels. Pedicels with long scattered straight or curved hairs, at flowering (20) 30–45 mm long, at fruiting (22) 30–55 mm long. Sepals 5, narrowly lanceolate, 6–8 mm long. Petals 5, sub-equal, 8–9 × 4–5 mm, obovate, bright yellow. Stamens 10, with very short filaments, ± 2 mm long, straight or slightly curved, anthers in three series, 5 small ± 3 mm long, 2 medium ± 4 mm long, slightly broader than the rest, 3 large ± 5 mm long. Ovary ± 10 mm long, densely hairy with straight or curved greyish hairs; style glabrous, narrow. Pods straight or slightly curved in the middle, 15–50 × 3–5 mm, flattened, with short curved hairs. Seeds not seen.

Diagnostic Characters — Chamaecrista falcata is distinguished by its long stalked extrafloral nectaries (1.0– 1.5 mm), long pedicels (30–45 mm long at flowering), and widely spaced leaves and broadly falcate leaflets (> 1.5 mm wide). The species has previously been confused with C. capensis but is readily distinguished from the C. capensis varieties by the long stalked extrafloral nectaries 1.0– 1.5 mm long ( Fig. 3H ) (less than 1 mm in C. capensis ), fewer and wider leaflets (more and narrower leaflets in C. capensis ) and small flowers (large in C. capensis ). The species shares the stalked extrafloral nectaries with Chamaecrista grantii Standl. , but differs in the falcate leaflets (oblong in C. grantii ), extrafloral nectaries on longer stalks, 1.0– 1.5 mm (less than 1 mm in C. grantii ), the strongly excentric leaflet midribs (rarely so in C. grantii ) and the smaller petals (8–9 × 4–5 mm in C. falcata vs. 10–14 × 6–9 mm in C. grantii ).

Distribution and Ecology —The species is currently known only from the summer rainfall region of South Africa. It occurs in the Waterberg in Limpopo, and in the HluhluweUmfolozi Park (formerly known as Hluhluwe-Imfolozi Game Reserve) in KwaZulu-Natal in grasslands on rocky or sandy soil at elevations below 240 m ( Fig. 8 ). Flowering from November to January.

Additional Specimens Examined — South Africa. — LIMPOPO: 2428 (Nylstroom): 7 miles (ca. 11 km) E of Magalakwin causeway (–BB), 10 Jan 1955, Mogg 24430 ( PRE) . — KWAZULU-NATAL: 2732 (Ubombo): 16 km from Jozini on road to Ingwavuma (–AC), 28 Nov 1978, Germishuizen 01016 ( PRE) . 2832 (Mtubatuba): Hluhluwe Game Reserve (–AA), 11 Nov 1954, Ward 2439 ( PRE , NU) ; Gunjaneni (–AB), 16 Nov 1955, Ward 2709 ( NU) .

Figures

FIG. 3. Extrafloral nectaries of Chamaecrista species. A. C. mimosoides, sessile, circular or circular-elliptic. B. C. capensis var. capensis, circular, sub-sessile or attached on small stalk. C. C. biensis, circular, concave, sub-sessile or raised on small stalk. D. C. comosa subsp. capriconia, elliptic, sessile, spreading over the petiole. E. C. comosa subsp. comosa, sessile, slightly sunken in petiole. F. C. grandiglandulata, large, sessile, elliptic, overlapping the sides of petiole. G. C. gordon-grayei subsp. longipedicellata, sub-sessile to sessile, circular. H. C. falcata, extrafloral nectaries, long stalked, concave on top. Vouchers: A. Burtt & Hilliard 3215 (NU). B. Walker 119 (PRE). C. Phelan 1120 (PRE). D. Burger 292 (PRE). E. Arnold 792 (NU). F. Ward 1219 (NH). G. De Winter and Wiss 4423 (PRE). H. Ward 2439 (PRE).Scale bars = 5 mm).

FIG. 8. Known distribution of Chamaecrista falcata in southern Africa.