Centothecoideae

Zeugites pittieri, photographed by Growin.

Belongs within: Poaceae.

The Centothecoideae is a smaller assemblage of grasses with uncertain support, though members may be united by the presence of an epiblast and fused styles (Grass Phylogeny Working Group 2001).

Characters (from Grass Phylogeny Working Group 2001): Plants annual or perennial (rhizomatous or stoloniferous), herbaceous or reedlike, of warm temperate woodlands and tropical forests. Culms solid or hollow. Leaves distichous; abaxial ligule absent or present as a line of hairs (Calderonella, Thysanolaena); adaxial ligule membranous or ciliate, or membranous with ciliate margins; blades relatively broad to narrow, often pseudopetiolate, venation parallel; sheaths sometimes auriculate. Inflorescences racemose or paniculate, bracts outside of the spikelets absent. Spikelets bisexual or unisexual, (1 to)2- to many-flowered with reduction either above or below the fertile florets, often compressed laterally; lemma lacking uncinate macrohairs, if awned, the awn single; palea usually well developed, sometimes relatively short; lodicules 2 or absent, ± cuneate, many-nerved or less commonly not or scarcely vascularized; stamens (1 to)2 or 3; ovary glabrous, apical appendage absent, haustorial synergids presumed absent, styles 2, free or fused, close, stigmas 2. Caryopsis with the hilum basal, punctiform; endosperm hard, without lipid, containing simple or compound starch grains; embryo small or large, the epiblast present, scutellar cleft present, mesocotyl internode present, embryonic leaf margins overlapping. Basic chromosome number: x = 12 (x = 11 or 12? in Thysanolaena). Foliar anatomy. Mesophyll nonradiate, often with an adaxial palisade layer, fusoid-like cells frequently present as extensions of the outer parenchyma bundle sheath, arm cells absent; Kranz anatomy absent; midrib simple; adaxial bulliform cells large. Foliar micromorphology. Stomata with dome-shaped and/or triangular subsidiary cells; bicellular microhairs present, panicoid-type; papillae absent. Photosynthetic pathway. C₃.

<==Centothecoideae [Centostecoideae]
    |  i. s.: Centotheca [Centotheceae] GPWG01
    |           `--C. lappacea GPWG01
    |         Cyperochloa Lazarides & Watson 1987 GPWG01
    |         Calderonella GPWG01
    |         Spartochloa GPWG01
    |--Chasmanthium GPWG01
    |    |--C. latifolium GPWG01
    |    `--C. laxum GPWG01
    `--+--Thysanolaena [Thysanolaeneae] GPWG01
       |    `--T. maxima GPWG01
       `--Zeugites GPWG01
            |--Z. americana J87
            |    |--Z. a. var. americana J87
            |    `--Z. a. var. haitiensis J87
            `--Z. pittieri GPWG01

*Type species of generic name indicated

REFERENCES

[GPWG01] Grass Phylogeny Working Group. 2001. Phylogeny and subfamilial classification of the grasses (Poaceae). Annals of the Missouri Botanical Garden 88 (3): 373-457.

[J87] Judd, W. S. 1987. Floristic study of Morne La Visite and Pic Macaya National Parks, Haiti. Bulletin of the Florida State Museum – Biological Sciences 32 (1): 1-136.