Brachiaria umbellata (Trin.) Clayton

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 : 216-218

11. Brachiaria umbellata (Trin.) Clayton in Kew Bull. 34: 559. 1980 (F ig. 8D–F, 11A).

Panicum umbellatum Trin., Gram. Panic. : 238. 1826.

Holotypus: MAURITIUS: sine loco, 1825, Sieber Hb. Maur. II. No. 34 ( LE Herbarium Trinii 996.1 microfiche!; iso-: BR [ BR0000008756435 ] image!, G [ G00022428 , G00022429 ] image!, H [ H1048911 , H1568372 ] image!, K [ K000244716 ]!, L [ L0043864 , L0043865 , L0043866 ] image!, MO [MO-1742146] image!, P [ P00450345 , P00450346 ]!, US [US-2903023 fragm., US-144576]!, W [W0000261, W0000262, W0000263, W0000264, W1 8 8 9 0 2 1 1 2 5 2, W1 8 8 9 0 2 3 6 4 3 0, W1 8 8 9 0 2 3 6 4 3 1, W18890236432, W18890236433 ] image!).

= Panicum nossibense Steud., Syn. Pl. Glumac. 1(6): 419. 1854. = Panicum umbellatum subsp. nossibense (Steud.) A. Camus in Notul. Syst. (Paris) 15: 414. 1959. Lectotypus (designated here): MADAGASCAR. Reg AIANA [Prov. Antsiranana]: Nosy Be , VI.1847, Boivin 1962 or s.n. (P [ P00450237 ]!; isolecto-: K [ K000805712 ]!, P [ P00450238 , P00450239 ]!, US [US-1389878 fragm.]!, W [ W0023752 ] image!).

Stoloniferous mat-forming perennial, prostrate with ascending flowering culms, to 30 cm high, culms much branched, rooting at nodes, glabrous or finely pilose. Leaf sheath glabrous to pubescent. Ligule a line of hairs. Leaf blade narrow-lanceolate, thickly chartaceous, 1–3(–4) × 0.2–0.6 cm, glabrous to pubescent on both sides. Inflorescence racemose, slender, open or contracted, 1.5–5.5 cm long. Racemes 4–8, 1.5–5.5 cm long, erect, decreasing in length upwards, on a common axis 0–2 cm long, sometimes with secondary branches, rhachis narrow, with trichomes 1–2 mm long, spikelets not overlapping with adjacent spikelets, single, on pedicels of uneven length, bare at base. Spikelets elliptic, apically acute, 1.5–2 mm long, drying whiteish, often with a purple tinge. Lower glume absent or ⅛–⅓ as long as spikelet, membranous, obtuse to emarginate, with no veins, glabrous, orientation relative to rhachis variable. Upper glume as long as spikelet or a little shorter, membranous, 3–5-veined, glabrous or sometimes finely pilose. Lower floret infertile, palea absent. Lower lemma membranous, 5-veined, glabrous or sometimes finely pilose. Upper lemma acute, shiny to rugulose.

Distribution and ecology. – Madagascar, Comores, Seychelles, Mauritius, Rodrigues. Its status as an island group endemic is not clear: scattered records from Malawi, Mozambique, Tanzania, and Zimbabwe are most likely repeated introductions (F ig. 9).

F orms the dominant ground cover across significant areas of Madagascar and surrounding islands except the arid southwest. Abundant especially in sandy coastal areas but also on highland grazing lawns not affected by fire, and mid-elevation forest clearings, at elevations 0–1600 m. Common lawn grass. Apparently unable to tolerate the aridity of the southwest.

Notes. – Abundant and ecologically significant species. Introduced as a lawn grass to several localities in southern Africa (CLAYTON & RENVOIZE, 1982), and known as “coconut lawn”, “gazon cocotier” in Mayotte [P00290436]. Considerable variability across the range becomes visible when examined under a binocular microscope: occasionally the lower glume is absent altogether, fine trichomes can appear on the spikelet, and the upper lemma can be either shiny or finely rugulose.

Boivin’s Nosy Be collections of Brachiaria umbellata are numerous and it is not possible to verify which ones may have originally constituted a single gathering, or which exact sheet STEUDEL (1854) may have been referring to as “Boivin legit in Ins. Nossibé”, not citing a collection number. The more comprehensive and fully labelled sheets of these collections bear the number 1962 and a collection date of June 1847, while others only bear the printed date range 1847–1852. The lectotype selected here is the best quality and most extensively annotated sheet of Boivin’s herbarium.

Selected specimens examined. – MADAGASCAR. Reg. Amoron’i Mania [Prov. Fianarantsoa]: Ambatofinandrahana , Itremo, pepinière de la NAP à Ihazofotsy, 21.II.2014, Nanjarisoa et al. 164 ( K, TAN) . Reg. Analamanga [Prov. Antananarivo]: Manjakandriana , 4.IV.1951, Bosser 647 ( P) ; Antananarivo, Tsimbazaza, IV.1961, Bosser 15353 ( P, TAN) ; Beronono, c. 4 km from Ankazobe to Ankafobe , 8.V.2017, Solofondranohatra & Razanatsoa 1020 ( K, P, TAN) . Reg. Analanjirofo [Prov. Toamasina]: Soanierana Ivongo , Manankinany, 25.X.1986, Pettersson & Nilsson 38 ( P) . Reg. Anosy [Prov. Toliara]: Vinanibe près du F ort-Dauphin, 14.VIII.1932, Decary 10292 ( P) ; Taolagnaro , Mandromodromotra, I.1959, Peltier & Peltier 1497 ( P, TAN) ; Sainte-Luce , Ambandrika , 29.II.2012, Ramananjanahary et al. 558 ( P) . Reg. Atsinanana [Prov. Toamasina]: Ilaka-Est , XII.1962, Bosser 16882 ( K, P, TAN) ; Tamatave , III.1932, Jard. Bot. Tananarive 324186 ( P, TAN) . Reg. Boeny [Prov. Mahajanga]: Ankarafantsika NP office, 14.II.2017, Vorontsova & Duncanư Rice 2092 ( K, P, TAN) . Reg. AIANA [Prov. Antsiranana]: Nosy-Be , Ambatoloaka , VIII.1959, Bosser 13230 ( P, TAN) ; Sahafary F orêt , VI.1970, Bosser 20382[b] ( K) ; Manongarivo , Besinkara , Ambalafary , 13.V.1995, Gautier & Chatelain 2644 ( G, K, P, TAN) . Reg. Ihorombe [Prov. Fianarantsoa]: près de Ranotsara , XII.1963, Bosser 18728 ( P, TAN) . Reg. Melaky [Prov. Mahajanga]: marais d’Antsalova , X.1963, Morat 163 ( TAN) . Reg. Sofia [Prov. Mahajanga]: sur le Mahajamba à Beronono , I.1907, Perrier de la Bâthie 11144[a] ( P) . Reg. Vatovavy [Prov. Fianarantsoa]: env. d’Ambila , 18.III.1951, Benoist 829 ( P, TAN) .