Urochloa

Urochloa Beauv.

(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.

 Urochloa panicoides, Antwerpen, port (Kattendijkdok), unloading quay for cereals, August 1996, F. Verloove Urochloa panicoides, Antwerpen, port (Kattendijkdok), unloading quay for cereals, August 1996, F. Verloove

 


Literature:

Ashalatha V.N. & Nair V.J. (1993) Brachiaria Griseb. and Urochloa P. Beauv. (Poaceae) in India — a conspectus. Bull. Bot. Surv. India 35: 27–31.

Grenfell A.L. (1989) Aliens and adventives. Adventive news n°40. BSBI News 51: 31 (+ frontpage).

Hatch S.L. (2010) Urochloa subquadripara (Poaceae: Paniceae) new to Texas and a key to Urochloa of Texas. Phytoneuron 2010-8: 1-4.

Morrone O. & Zuloaga F.O. (1992) Revisión de las especies sudamericanas nativas e introducidas de los géneros Brachiaria y Urochloa (Poaceae: Panicoideae: Paniceae). Darwiniana 31: 43–109.

Morrone O. & Zuloaga F.O. (1993) Sinopsis del género Urochloa (Poaceae : Panicoideae : Paniceae) para Mexico y America central. Darwiniana 32(1-4): 59-75.

Salariato D.L., Zuloaga F.O., Giussani L.M. & Morrone O. (2010) Molecular phylogeny of the subtribe Melinidinae (Poaceae: Panicoideae: Paniceae) and evolutionary trends in the homogenization of inflorescences. Molecular Phylogenetics and Evolution 56: 355-369.

Sendulsky T. (1978) Brachiaria: taxonomy of cultivated and native species in Brazil. Hoehnea 7: 99-139.

Torres Gonzalez A.M. & Morton C.M. (2005) Molecular and morphological phylogenetic analysis of Brachiaria and Urochloa (Poaceae). Molec. Phylogenet. Evol. 37: 36-44.

Veldkamp J.F. (1996) Brachiaria, Urochloa (Gramineae-Paniceae) in Malesia. Blumea 41: 413-437.

Veldkamp J.F. (2004) Miscellaneous notes on mainly southeast Asian Gramineae. Reinwardtia 12: 135-140.

Webster R.D. (1987) The Australian Paniceae (Poaceae): 322 p. J. Cramer, Berlin and Stuttgart.

Wipff J.K. & Thompson R.A. (2003) Urochloa. In: Barkworth M.E. & al. (eds.), Flora of North America north of Mexico, vol. 25. Oxford University Press, New York-Oxford: 492-507.

Taxonomic name: 
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith