Panicum capuronii A. Camus in Bull. Soc. Bot. France 103: 613. 1957

Vorontsova, Maria S., 2018, Revision of the group previously known as Panicum L. (Poaceae: Panicoideae) in Madagascar, Candollea 73 (2), pp. 143-186 : 154

6. Panicum capuronii A. Camus in Bull. Soc. Bot. France 103: 613. 1957 ( Fig. 5 ).

Lectotypus (designated here): MADAGASCAR. Prov. Toliara: forêt d’Iera à env. 30 km W d’Ankazoabo, IV.1955, Humbert 29717 ( P [ P00450282 ]!; isolectotype: P [ P00450283 ]!) .

Delicate annual, erect, 5– 15 cm tall, the culms glabrous with some cilia at the nodes. Leaf sheaths pilose on the margins. Ligule a ciliolate membrane. Leaf blades elliptic, flat, membranous, cordate and amplexicaul at base, 2.5–5 × 0.5–0.9 cm, drying yellow-green, glabrous on both sides. Panicles terminal, fully exserted, 3–6 cm long, linear, the branches lax, ascending, with glandular patches, glabrous. Spikelets ovate, asymmetric, apically obtuse, c. 1.5 mm long, green, opening only partly. Lower glume equalling or slightly exceeding the spikelet, membranous, acute, 1–3-veined, glabrous to pubescent, separated from the rest of the spikelet by a short internode. Upper glume as long as the spikelet, herbaceous, 5-veined, hirsute with bulbous-based trichomes c. 1 mm long at maturity. Lower floret male, with a fully developed palea. Lower lemma thinly cartilaginous, 5-veined, sometimes hooded, glabrous. Upper lemma with sparse minute elongated verruccae towards the upper half, often dehiscing before the lower floret.

Distribution and ecology. – Endemic to Madagascar. Shade understory of seasonally dry forest, c. 400 m ( Fig. 2B ).

Notes. – Known from the type collection only.

Close to P. subhystrix but differs by the shape of the verrucae on its upper lemma which are sparse and elongated, not rounded. Panicum subhystrix occupies a different environmental niche of higher elevation rocky and savanna habitats on the High Plateau.

Brachiaria capuronii A. Camus has a short lower glume and spikelets arranged along racemes, and is a different species likely not directly related to Panicum capuronii . Confusion is possible since Brachiaria capuronii has broad membranous leaves somewhat similar to those of Panicum capuronii and comes from a similar area of Madagascar.

Figures

Fig. 5. – Panicum capuronii A. Camus. A. Habit; B. Ligule; C. Panicle branch; D. Spikelet; E. Lower glume, dorsal view; F. Upper glume, ventral view; G. Upper glume, dorsal view; H. Lower lemma, ventral view; I. Lower lemma, dorsal view; J. Lower palea, ventral view; K. Lower palea, dorsal view; L. Upper floret, ventral view; M. Upper lemma, ventral view; N. Upper lemma, dorsal view; O. Upper palea, ventral view; P. Upper palea, dorsal view. [Humbert 29717, P] [Drawing: Lucy T. Smith]

Fig. 2. – Distribution maps. A. Adenochloa hymeniochila (Nees) Zuloaga (stars), Panicum ambositrense A. Camus (triangles), P. andringitrense A. Camus (circles) and P. ankarense A. Camus (squares); B. Panicum brevifolium L. (stars), P. capuronii A. Camus (triangle), P. cinctum Hack. (circles) and P. crystalinum Judz. & Voronts. (squares).