Trichanthecium pusillum (Hook.f.) Zuloaga

Zuloaga, Fernando Omar, Aliscioni, Sandra, Delfini, Carolina & Salariato, Diego Leonel, 2024, Old World species of Trichanthecium (Poaceae: Panicoideae: Paniceae) including a new species from the Democratic Republic of Congo, Phytotaxa 646 (3), pp. 230-264 : 251-253

11. Trichanthecium pusillum (Hook.f.) Zuloaga , comb. nov.

Panicum pusillum Hooker (1864: 227) .

Lectotype (designated as “holotype” by Clayton & Renvoize 1982: 490):— CAMEROON. Cameroon Mountains , 7000–8000 ft, December 1882, G. Mann 2090 ( K [ K000182419 !]) . Fig. 10

Panicum tylanthum Hack ex Engler (1891: 118) .

Lectotype (here designated):— ETHIOPIA. “ Abyssinien auf Felsen am Hedscha, G. H. W. Schimper 1095 (K [000255571!]).

Panicum nymphoides Renvoize (1989a: 545) .

Type:— MALAWI. Mount Mulanje, 4 February 1971, O. M. Hilliard & B. L. Burtt 6396 (holotype K [000318207!]), syn. nov.

Annual; culms (2–) 15–30 cm tall, decumbent, branching and rooting at the lower nodes, rarely erect; internodes cylindrical, 1–3 cm long, hollow, glabrous; nodes dark, pilose. Sheaths striate, 1–2 cm long, hirsute, with tuberculate hairs. Ligule membranous, 0.4 mm long. Blades ovate-lanceolate, 0.5–4(4.2) × 0.2–0.6 cm, narrowed at the base, flat, membranous, pilose, the apex acuminate. Inflorescence a terminal, short-exserted lax panicle 1–2(4.5) × 1–3 cm, peduncle cylindrical, 2–4 cm long; main axis flexuous, hispid, first-order branches alternate, divergent, deflexed or not, spikelets solitary on flexuous pedicels, 1–3 mm long; axillary inflorescences present, similar to the terminal one. Spikelets ellipsoid, 1.5–2 × 0.7–0.8 mm, hirsute, with tuberculate hairs, occasionally glabrous, greenish, acute; lower glume 1.2–1.5 mm long, 1/2 to 4/5 the length of the spikelet, 3-nerved, acuminate, membranous; upper glume and lower lemma subequal, 5–7-nerved, acute, membranous, upper glume early deciduous; lower palea reduced, hyaline, glabrous; lower flower absent. Upper anthecium narrowly ovoid, 1.5–1.8 × 0.6–0.8 mm, smooth, shiny, indurate. Caryopsis ovoid, 1.2 × 0.6 mm; hilum punctiform, embryo 1/3 the length of the caryopsis.

Distribution and habitat: —Widely distributed from Ethiopia to Kenya, Malawi, and Tanzania in Tropical East Africa. It is found in clefts, mountain grassland or bushland and forest margins; at 1350–3300 m elevation ( Clayton & Renvoize 1982).

Chromosome number: —2n = 18 ( Morton 1993).

Typification: —The protologue of P. tylanthum mentions a single specimen, Schimper 1095. Since no material was found at B or W, relating it to Hackel or Engler, a specimen of from K [0000255571!] is here selected as the lectotype.

Note: — Brown (1977) reported that this is a non-Kranz species with a δ13C value of –26.8.

Representative material examined: — BURUNDI. Prov. Muramwya: Mugongomanga , 14 May 1982, Reekmans 11225 ( MO) ; Teza, 31 May 1978, Bouharmont 11329 ( BR). CAMEROON. Cameroon Mountains, Maitland 1218 ( K, US). DEMOCRATIC REPUBLIC OF CONGO. Kabare , Mugigo , 9 May 1959, Leonard 4097 ( BR) ; Kivu , Kalehe, Petit s.n. ( BR). KENYA. 15 miles SSW of Nyeri, 14 November 1956, Bogdan 4347 ( K, US) ; Nakuru , 21 September 1929, Hitchcock 25113 ( US) ; Nakuru, 4 miles W of Nakuru, 10 October 1951, Bogdan 3283 ( K, US). MALAWI. Northern Province. Nyika Plateau , below main bridge Dam 1, 22 March 1976, Phillips 1518 ( MO). NIGERIA. Obudu cattle ranch , Birnas 222 ( K) ; Chappal Waddi, Gangirwal, Jackson et al. 2023 ( K). RWANDA Montagnes a l’Est de Kisenyi , May 1929, Humbert 8478 ( BR). TANZANIA. Kilimanjaron; Peters Hut to Marangu, 6 September 1929, Hitchcock 24649 ( US). Nyassa Hochland , Kyimbala , 15 May 1912, Stolz 1271 ( US) .

Figures

FIGURE 10. Trichanthecium pusillum. A. Habit. B. Ligular region. C. Detail of a branch of the inflorescence. D. Spikelet, lateral view. E. Spikelet, ventral view. F. Spikelet, dorsal view. G. Lower lemma. H. Lower lemma with upper anthecium. I. Upper anthecium, dorsal view. J. Upper anthecium, ventral view. K. Upper palea with lodicules. L. Stamens of the upper anthecium. (Bogdan 3283 US).