10. Panicum danguyi A. Camus in Bull. Soc. Bot. France 72: 706. 1925.

Lectotypus (designated here): MADAGASCAR. Prov. Antsiranana: massif de Manongarivo, V.1909, Perrier de la Bâthie 11072 (P [P00450258]!; isolectotype: P [P00450259]!).

= Panicum danguyi var. mahavavyensis A. Camus in Bull. Soc. Bot. France 99: 143. 1952. Lectotypus (designated here): MADAGASCAR. Prov. Antsiranana: massif de Marivorahona au SW de Manambato, 18.IV.1951, Humbert & Capuron 25655 (P [P00450261]!; isolectotype: G [G00341774]!, K!, MO!, P [P00450260, P00450262]!, PRE!, SI!, TAN!), syn. nov.

= Panicum tsaratananense A. Camus in Bull. Soc. Bot. France 77: 638. 1931. Lectotypus (designated here): MADAGASCAR. Prov. Antsiranana: Mt Tsaratanana, IV.1924, Perrier de la Bâthie 16369 (P [P00450236]!; isolectotype: K [K000805597]!; P [P02608161]!), syn. nov.

= Panicum tsaratananense var. diffusum A. Camus in Bull. Soc. Bot. France 105: 246. 1958. Holotypus: MADAGASCAR. Prov. Antsiranana: Mt Tsaratanana, IV.1923, Perrier de la Bâthie 16372 (P [P02608160]!), syn. nov.

Ascending wiry annual or perennial, rooting at lower nodes, to 50 cm long, the culms glabrous. Leaf sheaths glabrous or with ciliate edges. Ligule a lacerate ciliolate membrane. Leaf blades ovate to linear-lanceolate, flat or folded, reflexed at maturity, membranous, 1–6.5 × 0.1–0.4 cm, drying yellowgreen to red-green, glabrous to pubescent on both sides. Panicles terminal, partly or fully exserted on a peduncle to 3 cm long, 3–5 cm long, linear to narrowly elliptic, dense, the branching distichous or in threes, the branches appressed, sometimes with white cilia exceeding the spikelet, the pedicels 0.5–3 mm long. Spikelets ovate to oblong, apically rounded to acute, 1.2–1.5 mm long, yellowish or purple, never gaping open. Lower glume a nerveless vestige of variable shape. Upper glume as long as the spikelet, membranous, 3-veined, with small trichomes between the veins. Lower floret barren, without a significant palea. Lower lemma translucent, 3–5-veined, with minute trichomes between the veins or towards the apex. Upper lemma smooth, shiny, pale.

Distribution and ecology. – Endemic to the mountains of northwestern Madagascar, 1700–2500 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. flacourtii A. Camus, P. manongarivense A. Camus, and P. vohitrense A. Camus (Malagasy regional endemics) as well as P. mitopus K. Schum. (Madagascar and East Africa). Species boundaries within this group remain unclear. Panicum danguyi can be distinguished by its condensed panicles with pale yellowish to purple spikelets evenly distributed throughout the panicle.

The epithet of P. danguyi var. mahavavyensis is sometimes cited with an alternative spelling ‘mahavavensis’ which is incorrect because the protologue latinized the Malagasy place name ‘Mahavavy’ preserving the final vowel (CAMUS 1952b: 143).

The lectotype sheet of P. danguyi is chosen because it has been annotated by Camus. The lectotype sheets of P. danguyi var. mahavavyensis and P. tsaratananense are chosen because of their superior flowering material as well as an annotation by Camus.

Additional material examined. – MADAGASCAR. Prov. Antsiranana: Mt Tsaratanana, V.1926, Perrier de la Bâthie 16371 (P [P03182747]).