Sporobolus, Brown, 1810

Longhi-Wagner, Hilda M., Alves, Ruy J. V., Da Silva, Nílber G. & Guimarães, Alessandra R., 2013, A new species of Sporobolus (Poaceae, Chloridoideae) from Trindade Island, Brazil, with comments on the distribution of the genus in the South Atlantic, Phytotaxa 144 (1), pp. 13-21 : 18

Key to the species of Sporobolus from Ascension and Trindade Islands

1. Both glumes shorter than the anthecium. Continental Africa and weedy on Ascension............................. S. africanus

- Lower glume shorter than the anthecium, the upper subequal to longer than the anthecium ...................................... 2

2. Plants 70–90 cm tall, with short rhizomes, forming dense tussocks. Panicle open to lax, 5.5–17 cm long. Leaf blades 30–60 cm × 1.2–1.5 mm, the sheaths 3–5 mm wide, conspicuously wider than the leaf-blades. Spikelets 3–3.5 mm long. Trindade Island ............................................................................................................................... S. nesiotioides

- Plants 6–45(–65) cm tall, with short or long rhizomes. Panicle contracted, 1–11 cm long. Leaf blades (1.3–)2.3–20(– 28) cm × (1.5–)2–3(–5) mm, continuous with the leaf sheaths. Spikelets 2–3(–3.5) mm long ................................... 3

3. Plants up to 65 cm tall, with long and slender rhizomes, not forming tussocks. Pantropical, mostly on sandy coastal strands (up to 600 m elevation on volcanic tuff on Trindade Island) ......................................................... S. virginicus

- Plants 6–45 cm tall, with short rhizomes, forming lax tussocks. Ascension Island.................................................... 4.

4. Plants 6–10 cm tall. Panicle 1–2 cm long, largely hidden in the leaves. Spikelets ca. 2 mm long. Ascension Island, endemic, endangered ................................................................................................................................. S. caespitosus

- Plants 30–45 cm tall. Panicle 5–9 cm long, exserted. Spikelets 3–3.5 mm long. Ascension Island, endemic, considered extinct ......................................................................................................................................................... S. durus