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Coelorachis Brongn.

Kingdom: Plantae Rank: Genus Parent: Poaceae Status: Valid

Common Names:

  • JOINT-TAIL - English, United States of America

Morphological Description

Diagnosis: Perennials with or without rhizomes; ligule a short ciliate membrane; leaf blades flat, 8 mm or less wide; inflorescence a very slender, elongate, cylindrical, spike-like raceme (pencil-like but much smaller in diam.), breaking apart at the nodes of the inflorescence axis, the base of each internode with a niche on one side into which the spikelets fit closely; spikelets awnless, in pairs of 1 sessile and fertile and 1 pedicelled, reduced, and sterile; sessile spikelets with 2 florets, the lower sterile, the upper fertile; pedicels as broad as or broader than reduced spikelets.


Notes: A mainly tropical genus of ca. 20 species (Allen 2003b) related to Rottboellia, Rhytachne (Clayton & Renvoize 1986), and Mnesithea (Veldkamp et al. 1986). Generic boundaries among Coelorachis and its relatives have long been unsettled, and the species treated here have sometimes been put into Manisuris (e.g., Correll & Johnston 1970) or Mnesithea (e.g., Veldkamp et al. 1986; Jones et al. 1997; Hatch 2002; Turner et al. 2003). However, Coelorachis seems to be “sufficiently distinct to be maintained until more data are available” (Allen 2003b), and we are thus following J. Wipff (pers. comm.), Kartesz (1999), Yatskievych (1999), and Allen (2003b) in treating the species in Coelorachis. Like all members of the Andropogoneae, Coelorachis is characterized by C₄ photosynthesis (Kellogg 2000a). (Greek: coelo, hollow, and rachis, spine or backbone, possibly from the niches in the rachis (= inflorescence axis) into which the spikelets fit) (subfamily Panicoideae, tribe Andropogoneae)