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

954 POACEAE/GLYCERIA
limestone-derived soils; Bexar, Travis (BRIT), Bell, Comal, Hays (Turner et al. 2003), and Fayette
(Carr 2001) cos. in the sw part of East TX, also Aiken et al. (1997) mapped (without specific
counties) its occurrence from ne TX (roughly in the vicinity of Hopkins Co.) s and w through
the Post Oak Savannah and Blackland Prairie to e Edwards Plateau; also Blanco and Kendall
(Carr 2001) cos. in e Edwards Plateau; endemic to TX, the Wichita Mts. of OK (Aiken et al. 1997),
and AR (Darbyshire & Pavlick ined.). Darbyshire and Pavlick (ined.) indicate that this species is
“rare.” Mar–Jun. (RARE 2001, 2002b: G3S2S3)�
GLYCERIA R. Br. MANNA GRASS
Perennials, often with rhizomes or rooting at lower nodes; leaf sheaths closed for 3/4 or more of
their length; ligule a membrane; inflorescence an open or contracted panicle (rarely a raceme);
spikelets in ours with 3–14(–20) florets, awnless, disarticulating above glumes and between florets;
glumes unequal; lemmas usually with 7 strong, parallel veins, rounded on back; paleas often
as long or slightly longer than lemmas.
AA cosmopolitan but particularly temperate North American C3 genus of ca. 40 species
(Barkworth ined.), typically of wet places or shallow water; a number are good pasture grasses.
The genus resembles Puccinellia, and some species previously placed in Glyceria are now
treated in Puccinellia and Torreyochloa. Native Americans formerly used the seeds of some,
and in Europe, flour is made using the seeds of certain species (Yatskievych 1999). � All species
are palatable (Barkworth ined.), but under certain conditions Glyceria species are known to
be poisonous to livestock, due to the presence of dhurrin, a cyanogenic glycoside which is enzymatically
converted to hydrogen cyanide (Burrows & Tyrl 2001). (Greek: glyceros, sweet, referring
to the taste of the seeds of the type species) (subfamily Pooideae, tribe Meliceae)
REFERENCES: Church 1949; Tucker 1996; de Esparza & Maze 1997; Mejía-Saulés & Bisby 2000;
Barkworth ined.
1. Inflorescence branches usually short and stiffly erect or ascending (particularly at maturity), often
with spikelets to base of branches or nearly so; spikelets 8–20(–30) mm long, with 7–14(–20)
florets; lower glume ca. (1–)2–4 mm long; upper (longer glume) 2–5.1 mm long.
2. Lemmas 2.5–3.5 mm long, with short pubescence visible with 10X hand lens; anthers � 1 mm
long _______________________________________________________________________ G. arkansana
2. Lemmas usually 3.5–5.5 mm long, minutely scabrous, the hairs hard to distinguish even with
10X hand lens; anthers 1–2 mm long _________________________________________ G. septentrionalis
1. Inflorescence branches (at least lower) long and flexuous, bare of spikelets on the lower 1/3–1/2;
spikelets 2–4(–5) mm long, usually with 3–7 florets; lower glume �1(–1.4) mm long; upper
glume 0.8–1.3(–2) mm long __________________________________________________________ G. striata
Glyceria arkansana Fernald, (of Arkansas), ARKANSAS MANNA GRASS. Perennial similar to G.
septentrionalis, distinguished as in the key; leaf blades usually (3–)6–12 mm wide. Wet areas;
Fannin (Talbot property, BRIT), Bowie (BAYLU, TAES, Nixon et al. 1987), Red River (BAYLU),
and Lamar (Carr 1994) cos. in Red River drainage and Liberty (SBSC, TAES) and San Jacinto
(SBSC) cos. further s; also Fort Bend Co. (L. Brown, pers. comm.) in the Gulf Prairies and
Marshes; in TX primarily in the ne corner of the state; e U.S. from VA w to MO, OK, and TX.
Mar–May. While Gould (1975b) recognized G. arkansana, he indicated that it “is close to and
weakly differentiated from G. septentrionalis and probably should be treated as a variety of
that species.” Jones et al. (1997) treated it as a variety of G. septentrionalis, as did Yatskievych
(1999) and Hatch (2002). However, Allen (1992b), Tucker (1996), Kartesz (1999) Weakley (2000),
and Barkworth (ined.) recognize it at the species level. Until a detailed study can be carried out,
we are treating the two as different species. [G. septentrionalis Hitchc. var. arkansana (Fernald)
Steyerm. & Kucera]