Brachiaria fragrans A. Camus

Vorontsova, Maria S., 2022, Revision of some Malagasy forage grasses and their relatives within Brachiaria, Echinochloa, Moorochloa, and Urochloa, Candollea 77 (2), pp. 199-236 : 210-212

6. Brachiaria fragrans A. Camus in Bull. Soc. Bot. F rance 82: 22. 1935 (F ig. 6).

Lectotypus (designated here): MADAGASCAR. Reg. Atsimo-Andrefana [Prov. Toliara]: plateau calcaire au N du F iherenana, forêt sèche de F andrare à 40 km NE de Tulear , 400 – 700 m, III.1934, Humbert 14315 ( P [ P00450177 ]!; isolecto-: K [ K00024472 ]!, P [ P00450178 , P00450179 ]!) .

Stoloniferous perennial, ascending, to 2 m high, culms not branched, rooting at lower nodes, with a knotty rootstock, glabrous. Leaf sheath glabrous with ciliate margins. Ligule a ciliolate membrane. Leaf blade lanceolate, basally asymmetric and often cordate on one side, chartaceous, 8–18 × 1.2–2 cm, glaucous underneath, glabrous on both sides, often with bulbousbased trichomes near base. Inflorescence racemose, contracted, rarely fully exserted, 5–10 cm long. Racemes 3–4, 1–3.5 cm long, decreasing in length upwards, on a common axis 2–8 cm long, with no secondary branching, rhachis narrow, scaberulous, spikelets overlapping untidily with adjacent spikelets, paired, on pedicels of uneven length. Spikelets laterally compressed, ovate, apically acute, 3.5–4 mm long, white. Lower glume c. ⅔ as long as spikelet, chartaceous, (3–)5-veined, scaberulous, thick keel developing into a small apical wing, orientation relative to rhachis variable. Upper glume ¾ as long as spikelet, chartaceous, 5-veined, scaberulous, pinched at apex. Lower floret male, palea as long as lemma, anthers 3, c. 2.5 mm long. Lower lemma chartaceous, 5-veined, scaberulous, pinched at apex. Upper lemma acute, matte, smooth but not shiny, with an apical crest and minute trichomes at apex.

Distribution and ecology. – Endemic to the understory of seasonally dry forest and scrub to the north of Toliara, on rocks and limestone soils, at elevations of 30–700 m (F ig. 5).

Notes. – Brachiaria fragrans A. Camus seems to possess a property rarely seen in the Poaceae : an odour. On P03175998, Camus noted: “plante très intéressante découverte par le Professeur Humbert à 40 km, de Tulear, au N de F iherenana, sur le calcaire. F leurs assez odorantes [a very interesting plant discovered by Professor Humbert 40 km from Tulear, to the N of F iherenana, on limestone. Quite fragrant flowers]” while the type collection labels cite “fleurs à fine odeur de Lis! [flowers with a fine scent of lily!]” This mysterious species was not found in the wild during several expeditions searching for it conducted by the author.

The closest relatives of Brachiaria f ragrans in the Boivinellinae (Appendix) are also unusual Malagasy endemics. The only related species bearing some morphological resemblance it is B. bemarivensis, also a broad-leaved grass with spikelets that look white when fresh. The spikelets of B. fragrans are significantly larger, however, and resemble the genus Acroceras Stapf with their pinched upper glume and lower lemmas, and a crested upper lemma. Brachiaria fragrans differs from Acroceras ivohibense A. Camus by its white (not brown) spikelets and partly (not fully) exerted inflorescences.

Additional specimens examined. – MADAGASCAR. Reg. Atsimo-Andrefana [Prov. Toliara]: 50 km de Tulear, rte. de Sakaraha, III.1960, Bosser 14058 ( P) ; rte. Tulear PK 55, III.1964, Bosser 19160 ( P) ; Toliara ville, vallée du F iherenana, XI.1933, Humbert 11587 ( P) ; gorges du F iherenana entre Beantsy et Anjamala, I.1947, Humbert 19919 ( P) ; gorges de la Manombo, I.1947, Humbert 19972 ( P) ; Morombe, 15 km de Befandriana, 5.IV.1955, Humbert 29739 ( P) ; à 50 km de Tulear, rte. Tulear à Sakaraha, III.1960, KeraudrenưAymonin 751 ( P) .