Echinochloa serpens (Kunth) Voronts.

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 : 221-222

14. Echinochloa serpens (Kunth) Voronts. , comb. nov.

Panicum serpens Kunth, Rev. Gram. 1: 38. 1829 [nom. nov.]. Panicum parvifolium var. serpens (Kunth) Baker , F l. Mauritius: 438. 1877. Brachiaria serpens (Kunth) C.E. Hubb. in Kew Bull. 1939: 654. 1939.

Panicum repens Nees , F l. Bras. Enum. Pl. 2(1): 171. 1829 [nom. illeg., non P. repens L., 1762].

Holotypus: MAURITIUS: sine loco, Bory de St Vincent. No. 40 (B-W [ BW18793010 ] image!) .

= Brachiaria lateritica A. Camus in Bull. Soc. Bot. F rance 93: 89. 1946, syn. nov. Holotypus: MADAGASCAR. Reg. AIANA [Prov. Antsiranana]: env. de Diégo-Suarez, VIII.1933, Perrier de la Bâthie 19296 ( P [ P02233536 ]!) .

Stoloniferous mat-forming perennial, forming dense cushions, not rising more than c. 2 cm above ground, culms much branched, rooting at nodes, glabrous, nodes bearded. Leaf sheath pubescent. Ligule absent. Leaf blade narrow-lanceolate, membranous, 0.7–1.5(–1.8) × 0.08–0.12(–0.15) cm, sparsely to densely pubescent on both sides. Inflorescence capitate, not fully exserted, 0.3–0.5(–0.8) cm long, with 3–5(–8) spikelets, with no secondary branching, rhachis narrow, glabrous to pubescent, spikelets overlapping with adjacent spikelets, single, subsessile. Spikelets elliptic, apically acute, 1–1.5(–2) mm long, white to pale green. Lower glume ½– ⅔ as long as spikelet, membranous, acute, 3-veined, glabrous to apically pubescent, orientation relative to rhachis variable. Upper glume as long as spikelet or slightly shorter, membranous, pinched at apex, 5–7-veined, pubescent, often with bulbous-based hairs. Lower floret male, palea as long as lemma. Lower lemma membranous, pinched at apex, 5–7-veined, pubescent, often with bulbous-based hairs. Upper lemma acute, smooth, shiny, white becoming pale brown, with an apical green crest.

Distribution and ecology. – The only collection known from Madagascar is the type of Brachiaria lateritica A. Camus (F ig. 12) .

Notes. – Details of the species boundary between Echinochloa hubbardii and E. serpens are not altogether clear and require field work. These species seem to be sympatric, forming ground cover at low elevations on the islands. Herbarium specimens of E. serpens consistently differ from E. hubbardii by their more compact habit, uniform short leaf blades and short peduncles, and pubescence on leaf blades and spikelets. These two species are maintained here as separate taxa in agreement with Hubbard and the Kew collections as documented by CAMUS (1947), and also in agreement with BOSSER & RENVOIZE (2018). F or discussion of the relationship between E. hubbardii and E. serpens and their generic placement see the notes under E. hubbardii .

This species has historically been refereed to as “Panicum conglomeratum”; see notes under Echinochloa hubbardii . The protologue of Panicum repens Nees (NEES VON ESENBECK, 1829) cites “in insula Mauritii (Sieb. Herb. n. 34)” and this number is also cited by BAKER (1877) in his description of Panicum parvifolium var. serpens (Kunth) Baker. Unfortunately, Baker conflates this species with the superficially similar P. umbellatum Trin. (= Brachiaria umbellata in this treatment). The collection Sieber Hb. Maur. II. No. 34 is the type of Panicum umbellatum , and all the sheets examined clearly belong to Brachiaria umbellata , not Echinochloa serpens .