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

878 POACEAE/CYNODON
CYNODON Rich. BERMUDA GRASS
AA C4 genus of 9 species of tropical and warm areas of the Old World (Barkworth 2003e),
which including pasture and lawn grasses and troublesome weeds. Recent molecular studies
(Hilu & Alice 2000) indicate that Cynodon is related to Chloris and Eustachys. � All species
are reported to be potentially cyanogenic because of the glucoside dhurrin, which hydrolizes to
hydrocyanic acid (HCN) in the rumen of livestock (Burrows & Tyrl 2001). At least some species
of Cynodon have salt glands (= specialized epidermal structures for the excretion of excess salts
from leaf tissue) and are halophytic (= tolerant of salty or alkaline conditions) (Oross & Thomson
1982). (Greek: cyon, dog, and odous, tooth, from the close rows of tooth-like spikelets or the
hard scales on rhizomes) (subfamily Chloridoideae, tribe Cynodonteae)
REFERENCES: Harlan et al. 1969; de Wet & Harlan 1970a; Moreira 1984; Jones & Jones 1992;
Barkworth 2003e.
Cynodon dactylon (L.) Pers., (fingered), BERMUDA GRASS, BAHAMA GRASS, STAR GRASS. Rhizomatous
and stoloniferous, mat-forming perennial 10–40(–50) cm tall; culms mostly stoloniferous,
with only inflorescence-bearing shoots erect; leaf blades 1–2(–5) mm wide; leaf sheaths compressed,
keeled, with tufts of hairs at summit; lower leaf sheaths also pilose on back; ligule of
hairs 0.2–0.5 mm long; branches of inflorescence (2–)3–5(–9), usually digitately arranged at tip
of culm, 2–6(–8) cm long; spikelets with 1 perfect awnless floret, 1.7–2.5(–3.2) mm long, closely
overlapping, in 2 rows on a flattened or triangular branch; disarticulation above the subequal
glumes. Cultivated in TX since about 1882 for pasture and lawns (Mahler 1988), also a common
weed throughout TX on roadsides, disturbed areas, gardens, and moist habitats; sw Canada
(B.C.) and throughout most of the U.S. May–Oct. Native probably of Africa, but India has also
been suggested (not from Bermuda, despite the common name). [Capriola dactylon (L.) Kuntze]
This species was introduced to Georgia in 1751 and within 50 years was widespread in the e and
se U.S. (Tellman 1997). It is an important cause of hay fever and is potentially poisonous to livestock
due to the production of hydrocyanic acid under certain environmental conditions; it is
also reported to cause photosensitization, staggers syndrome, and acute respiratory distress
syndrome (ARDS) in livestock. The staggers syndrome (tremors, “head bob,” head shaking, incoordination)
may result from ergot-type alkaloids (see further discussion under Paspalum).
ARDS (a pneumonia-like condition sometimes referred to as “fog fever”) has affected cattle in
East TX in spring and is apparently linked to a change in food (e.g., movement to a lush pasture)
and an associated abrupt increase of l-tryptophan in the rumen of unaccustomed animals—this
is converted to a toxin which causes pulmonary emphysema and edema (Lewis &
Elvin-Lewis 1977; Fuller & McClintock 1986; Burrows & Tyrl 2001; Hart et al. 2001). BERMUDA
GRASS is viewed as one of the world’s worst weeds by some authorities (Holm et al. 1977) and affects
a variety of crops including corn, cotton, and sugarcane (Holm et al. 1977; Moreira 1984). It
is considered to be a noxious weed in AZ, CA, and UT (Kartesz 1999). However, BERMUDA GRASS
is the most commonly used tropical lawn grass (Clayton & Renvoize 1986) and is one of the
most important lawn and forage grasses in East TX. Improved hybrid strains are widely
planted as pasture grasses; the species is salt- and alkali-tolerant (Hatch et al. 1999). � � I
CYNOSURUS L. DOG-TAIL GRASS
AAn Old World C3 genus of 8 species (Barkworth ined.) native to Europe, Asia, and Africa.
Some species are used for pasture, hay, lawns, or playing fields; � others are considered serious
weeds (Watson & Dallwitz 1999). (Greek: cynos, dog and oura, tail, referring to the shape of the
panicle) (subfamily Pooideae, tribe Poeae)
REFERENCES: Tutin 1980; Tucker 1996; Yatskievych 1999; Thomas 2002; Barkworth ined.
Cynosurus echinatus L. (prickly), BRISTLY DOG-TAIL GRASS, SPINY DOG-TAIL GRASS, HEDGEHOG
DOG-TAIL, ROUGH DOG-TAIL. Glabrous annual; flowering culms 30–60(–90) cm tall, ascending;