Panicum flacourtii A. Camus in Bull. Soc. Bot. France 72: 449. 1925

Vorontsova, Maria S., 2018, Revision of the group previously known as Panicum L. (Poaceae: Panicoideae) in Madagascar, Candollea 73 (2), pp. 143-186 : 161-162

12. Panicum flacourtii A. Camus in Bull. Soc. Bot. France 72: 449. 1925 .

Lectotypus (designated here): MADAGASCAR. Prov. Antsiranana: Mt. Tsaratanana , IV.1924, Perrier de la Bâthie 16163 ( P [ P00450264 ]!; isolectotype: P [ P00450265 ]!) .

Ascending wiry annual or perennial, rooting at lower nodes, 10–60 cm tall, the culms glabrous. Leaf sheaths glabrous or with ciliate edges. Ligule a lacerate ciliolate membrane. Leaf blades lanceolate, flat, reflexed at maturity, chartaceous, 1–2 × 0.2–0.4 cm, drying red-green, sparsely hirsute on both sides. Panicles terminal, fully exserted on a peduncle 5–8 cm long, 3–6 cm long, ovate, diffuse, the branching distichous or in threes, the branches divergent, wiry, with occasional white cilia, the pedicels 1.5–4 mm long. Spikelets ovate-elliptic, apically acute, 1.3–1.5 mm long, purple, never gaping open. Lower glume a nerveless vestige of variable shape. Upper glume as long as the spikelet, membranous, 3-veined, glabrous or with a few small trichomes, dehiscing early. Lower floret barren, without a significant palea. Lower lemma membranous, 3–5-veined, with minute trichomes between the veins or towards the apex. Upper lemma smooth, shiny, pale brown.

Distribution and ecology. – Restricted to Mount Tsaratanana, forest with lichen c. 2000 m ( Fig. 8A ).

Notes. – This species is likely a member of a group of closely related wet forest and montane species also including P. crystalinum , P. danguyi , P. manongarivense , and P. vohitrense (Malagasy regional endemics) as well as P. mitopus ( Madagascar and East Africa). Species boundaries within this group remain unclear, particularly for P. flacourtii which is only known from two collections. If the open arrangement of the panicle is not a reliable character P. flacourtii could be conspecific with P. danguyi . Panicum flacourtii seems to occur in drier environments than other members of this group and can be distinguished by its open panicles with single spikelets, and purple to dark brown inflorescence branches and spikelets.

The lectotype is chosen for its superior flowering material.

Additional material examined. – MADAGASCAR. Prov. Antsiranana: Mt. Tsaratanana , IV.1924, Perrier de la Bâthie 16104 bis ( P [ P02608821 ]) .

Figures

Fig. 8. – Distribution maps. A. Panicum cupressifolium A. Camus (stars), P. danguyi A. Camus (triangles), P. dregeanum Nees (circles) and P. flacourtii A. Camus (squares); B. Panicum humbertii A. Camus (stars), P. humile Nees ex Steud. (triangles), P. ibitense A. Camus (circles) and P. inconspicuum Voronts. (squares).