21. Panicum palackyanum A. Camus in Bull. Soc. Bot. France 77: 638. 1931 (Fig. 12).

Lectotypus (designated here): MADAGASCAR. Prov. Fianarantsoa: massif d’Andringitra, IV.1921, Perrier de la Bâthie 13748 (P [P00450245]!); isolectotype: P [P00224772, P00450246] !).

Scandent perennial, branched, c. 2 m long, the culms and nodes glabrous. Leaf sheaths glabrous with a fringe of cilia on the margins. Ligule a membrane. Leaf blades linear to linear-lanceolate, flat, chartaceous, 5–8 × 0.4–0.6 cm, drying green-brown, imbricate on young shoots, spreading or retrorse, glabrous on both sides. Panicles terminal, fully exserted, 11–18 cm long, contracted, with long branches appressed to the axis partly, the branches not whorled, scaberulous, the spikelets paired in most of the panicle, on short pedicels 1.5 –3 mm. Spikelets elliptic, apically obtuse, 2.5 mm long, whitish to purple, partly open at maturity. Lower glume 1/3–½ as long as the spikelet, chartaceous, apically rounded to obtuse, 3–5-veined, glabrous, clasping. Upper glume 3/4 as long as the spikelet, herbaceous, apically truncate, 5–7-veined, glabrous. Lower floret male, with a fully developed palea. Lower lemma herbaceous, 5-veined, glabrous. Upper lemma smooth, shiny, pale, with a pronounced apical crest.

Distribution and ecology. – Andringitra forest understory, c. 1600 m (Fig. 10B).

Notes. – This isolated collection seems difficult to place: the crest on its upper lemma could suggest a relationship with Acroceras, clustering of the spikelets along primary inflorescence branches could indicate a relationship with Urochloa / Brachiaria s.l. (but the panicle is more branched than in Acroceras or Urochloa), it differs from Urochloa by its smooth upper lemma, while poorly visible veins on the spikelet and a short upper glume suggests a relationship with other Andringitra endemics Panicum andringitrense, P. spergulifolium, and P. cupressifolium (although P. palackyanum has longer panicles and paired spikelets).

The lectotype sheet is chosen for its best quality original material annotated by Camus.