7. NARDEAE W.D.J. Koch
Mary E. Barkworth

Plants perennial; cespitose. Culms annual, to 60 cm; internodes hollow. Sheaths open, margins not fused; collars glabrous, without tufts of hair at the sides; auricles absent; ligules scarious, not ciliate, those of the upper and lower cauline leaves usually similar; pseudopetioles not present; blades filiform, venation parallel, cross venation not evident, secondary veins parallel to the midvein; cross sections non-Kranz, without arm or fusoid cells, adaxial epidermes with bicellular microhairs, not papillate. Inflorescences terminal spikes, 1-sided, spikelets solitary, radial to the rachises; rachises with the spikelets partially embedded. Spikelets not compressed, triangular in cross section, with 1 floret, floret bisexual; rachillas not prolonged beyond the floret base; disarticulation above the glumes, beneath the floret. Glumes absent or vestigial; lower glumes a cupular rim; upper glumes absent or vestigial; florets 5–10 mm, not compressed; calluses poorly developed, glabrous; lemmas chartaceous, 3-veined, angled over the veins, most strongly so over the lateral veins, apices entire, awned, awns terminal, not branched, lemma-awn transition gradual, not evident; paleas subequal to the lemmas, hyaline, 2-keeled; lodicules absent; anthers 3; ovaries glabrous; styles 1. Caryopses fusiform, style bases not persistent; hila linear, more than 1/2 as long as the caryopses; embryos about 1/6 the length of the caryopses. x = 13.

There is only one genus, Nardus, in the Nardeae. Its relationships are obscure. Embryo characters, ligule texture, and DNA sequence data suggest it belongs in the Poöideae; the bicellular microhairs suggest a bambusoid or arundinoid affiliation. Its inclusion here in the Poöideae reflects the findings of the Grass Phylogeny Working Group (2001).

SELECTED REFERENCES Davis, J.I. and R.J. Soreng. 1993. Phylogenetic structure in the grass family (Poaceae) as inferred from chloroplast DNA restriction site variation. Amer. J. Bot. 80:1444–1454; Grass Phylogeny Working Group. 2001. Phylogeny and subfamilial classification of the grasses (Poaceae). Ann. Missouri Bot. Gard. 88:373–457.