(incl. Brachiaria (Trin.) Griseb.)
(excl. Moorochloa Veldk.)
As currently understood, Urochloa is a relatively large genus of ca. 110 species, mostly confined to the subtropics and tropics (Salariato & al. 2010). None is native in Belgium. Urochloa is not monophyletic and its generic limits are controversial. Most of the species previously placed in Brachiaria were transferred to Urochloa and the remaining species are now accommodated in Moorochloa (Veldkamp 2004), a small genus with only three species that are characterised by smooth upper lemmas (in Urochloa the upper lemmas are always conspicuously transversely rugose). From the genus Moorochloa one species was recorded between 1947 and 1949 as an exceptional and casual wool alien in the Vesdre valley: Moorochloa eruciformis (Smith) Veldk. [syn.: Brachiaria eruciformis (Smith) Griseb.]. The generic position of Moorochloa is confirmed by recent molecular research (Salariato & al. 2010). However, the final classification of Urochloa is pending and requires further studies. According to Salariato & al. l.c. it may either be accepted as a large paraphyletic genus including, among others, Brachiaria, Eriochloa and Megathyrsus or further segregated in several small monophyletic genera.
1 Spikelets paired, at least at mid-branch length, one sessile the other pedicellate. Axis of primary branches +/- triquetrous (not flat), ca. 0.4-0.6 mm wide. Primary branches not two-ranked (spikelets placed untidily) === Urochloa ramosa
1 Spikelets solitary throughout. Axis of primary branches flattened, 0.9-2.5 mm wide. Primary branches distinctly two-ranked === 2
2 Upper lemma awned, awn 0,6-1,2 mm long. Leaf blades and leaf sheaths densely pubescent with long and short patent hairs. Inflorescence axes (rachis) narrow, 0,9-1,2 mm wide, scabrous. Upper glume conspicuously 9-11-nerved. Inflorescence branches often closely spaced, usually at least some (sub-) opposite === U. panicoides
2 Upper lemma unawned, at most mucronulate. Leaf blades and leaf sheaths (sub-) glabrous. Inflorescence axes (rachis) wider, 1,3-2,5 mm wide, smooth. Upper glume inconspicuously 7(-9) nerved. Inflorescence branches widely spaced, never (sub-) opposite === 3
3 Lower glume 5-7 nerved. Glumes without a distinct rhachilla. Base of the leaf blades (sub-) cordate but not clasping the stems === U. platyphylla
3 Lower glume (7-)9-11 nerved. Glumes separated by a minute rhachilla. Base of the leaf blades (sub-) cordate to cordate, clasping the stems === U. plantaginea
Additional alien: Urochloa mutica (Forssk.) T.Q. Nguyen (syn.: Brachiaria mutica (Forssk.) Stapf, Panicum muticum Forssk.) (Afr., grain alien ?). A single Belgian record of Urochloa texana (Buckley) R.D. Webster (syn.: Panicum texanum Buckley) from the surroundings of Turnhout in the second half of the 20th century has never been confirmed by a herbarium collection.
The Asian weed U. distachya (L.) T.Q. Nguyen was observed as a weed in a container with a palm tree in Ostend in 2020. Photos substantiating this record are available here: https://waarnemingen.be/observation/200701099.
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