keys to the vascular plants of east texas - Botanical Research ...

POACEAE 797
Dissection is usually necessary to see the parts of the grass spikelet, and because of the small
size of the structures involved (e.g., lemmas, paleas), a dissecting scope or at minimum a hand
lens is often necessary for definitive identification. In the keys, measurements of glumes, lemmas,
or spikelets do not include awns (= hair-like or bristle-like appendages) if these are
present. (subclass Commelinidae—Cronquist; order Poales—APG II)
FAMILY RECOGNITION IN THE FIELD: mostly herbs with 2-ranked leaves having sheathing bases,
free blades, and ligules; culms round, with hollow or solid internodes; flowers small, inconspicuous,
reduced to stamens and pistils, subtended by 2 scale-like bracts each, and arranged in
very reduced spikes called spikelets; fruit a caryopsis; the � similar Cyperaceae (SEDGES) have
3-ranked leaves, often 3-sided culms with solid internodes, each flower subtended by 1 scalelike
bract, and fruit an achene; the � similar Juncaceae (RUSHES) have flowers with a small 6parted
perianth and capsular fruit.
REFERENCES: Nash 1909, 1912; Nash & Hitchcock 1915; Hitchcock 1931–1939, 1935, 1951; Silveus
1933; Tharp 1952a; Shinners 1954; Gould 1957b, 1968a, 1968b, 1973, 1975b, 1978; Box & Gould
1959; deWet 1981; Stebbins 1981a, 1982, 1985; Estes et al. 1982; Gould & Shaw 1983; McVaugh
1983; Campbell 1985; Coughenour 1985; Dahlgren et al. 1985; Redmann 1985; Clayton &
Renvoize 1986; Soderstrom et al. 1987; Hignight et al. 1988; Tucker 1988, 1990, 1996; Crins 1991;
Allen 1992b, 2004a; Watson & Dallwitz 1992; Powell 1994; Barker et al. 1995, 1998[1999]; Clark et
al. 1995; Kellogg & Linder 1995; Kellogg et al. 1996; Petersen & Seberg 1997; Peterson et al. 1997;
Hsaio et al. 1998; Kucera 1998; Soreng & Davis 1998, 2000; Hatch et al. 1999; Grass Phylogeny
Working Group 2000, 2001; Hilu 2000; Hilu & Alice 2000, 2001; Jacobs & Everett 2000;
Judziewicz et al. 2000; Kellogg 2000a, 2000b; Spangler 2000; Zuloaga et al. 2000; Mohlenbrock
2001; Hatch 2002; Mathews et al. 2002; Soreng et al. 2003; Zuloaga et al. 2003; Coffey & Stevens
2004; Sánchez-Moreiras et al. 2004.
KEY TO GENERA OF POACEAE
1. Culms woody, persisting for more than 1 season (bamboos).
2. Culms terete (= rounded); upper nodes often puberulent; base of midvein on lower leaf surface
without short hairs; branches 3–6 per node; plants of moist woods or low areas, native in
e part of East TX _______________________________________________________________ Arundinaria
2. Culms flattened above node on 1 side; upper nodes glabrous; base of midvein on lower leaf
surface often with short hairs along one side; branches usually 2(–3) per node; plants introduced
in East TX, persisting and spreading from cultivation ___________________________ Phyllostachys
1. Culms not woody, lasting 1 season only (sometimes lasting 2 seasons and somewhat woody in
Arundo).
3. Plants typically 2–7 m tall, often reed-like; inflorescences typically large, sometimes plumose
panicles up to 60(–130) cm long______________________________________________ Key A (page /798)
3. Plants usually � 2(–3+) m tall, not reed-like; inflorescences various.
4. Leaves with blades less than 1(–1.5) cm long, in clusters; inflorescences very inconspicuous
and obscured by the leaves, typically reduced to a single(–few) spikelet ________ Monanthochloe
4. Leaves with blades more than 1.5 cm long, usually not in clusters; inflorescences usually
conspicuous.
5. Spikelets fused with or closely fitted into the axis of the inflorescence or inflorescence
branches, forming a solid cylindrical or flattened spike ________________________ Key B (page /799)
5. Spikelets neither fused with nor closely fitted into the axis of the inflorescence or inflorescence
branches (but may be sessile and appressed).
6. Spikelets unisexual, the staminate and pistillate spikelets conspicuously different to
the naked eye _____________________________________________________ Key C (page /799)
6. Spikelets perfect, or if unisexual, not conspicuously different to the naked eye.
7. Spikelets with 2–many perfect florets and thus usually 2–many fruits forming per
spikelet.