BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Cynodon dactylon | Bermuda Grass 



GENERAL BOTANICAL CHARACTERISTICS : 
Bermuda grass is an introduced, perennial, mat-forming, warm season
grass. It is both rhizomatous and stoloniferous.  Erect or ascending
culms grow 0.3 to 1.3 feet (0.1-0.4 m) tall.  The panicle has two to
seven digitate branches [40].  Rhizomes are hard, scaly, and 0.06 to
0.13 inch (1.5-3.3 mm) in diameter.  Stolons are flattened and several
feet long, rooting at nodes [33].  Main root length per plant of four
cultivars ranged from 2.3 to 37.1 feet (0.7-11.3 m) while total root
length ranged from 43 to 4,854 feet (13.0-1,480 m).  Root hairs
contributed 64 to 95 percent of the total root length [32].


RAUNKIAER LIFE FORM : 
   Geophyte
   Hemicryptophyte


REGENERATION PROCESSES : 
Although Bermuda grass reproduces by seeds, it spreads most rapidly by
stolons and rhizomes.  Both stolon and rhizome branching intensities
were reduced in response to lower light and lower nutrient levels.
Average stolon and rhizome internode and total lengths are reported
under differing light and nutrient conditions [21].  In a study of six
Bermuda grass variants present in southern Africa, vegetative
reproduction was greater by rhizomes than by stolons [26].

Seeds, eaten by animals, are widely dispersed.  Bermuda grass seeds
present in domestic sheep dung germinated in "large numbers" [39].
Fernald [25] stated that seeds are rarely perfect.  Seed viability of
the six variants from southern Africa ranged from 0 to 3.5 percent [26].
Germination of viable seeds is low unless scarification occurs.  Seeds
treated with sulfuric acid for 10 minutes had 68 percent germination
after 4 days, but untreated seeds had only 4.5 percent germination after
10 days [12].  Prolonged exposure to acidic conditions decreases seed
germination.  Bermuda grass seeds did not germinate in sulfuric acid
solutions of pH 3 or less.  In pH 4 and 5 solutions, germination was
about 5 and 10 percent, respectively, after 12 days [68].

Bermuda grass seeds were present in intact soil/litter samples collected
for a germination study from an upland site in Arizona; seeds may have
come from an aerial seeding of an adjacent property.  Equal amounts of
Bermuda grass seeds germinated in the control sample and in the
scarified soil surface treatment.  No seeds germinated from soil samples
which had the litter manually removed or burned [29].


SITE CHARACTERISTICS : 
Although adaptable to most soil types, Bermuda grass grows best on
fertile, sandy to silty soils or alluvium [75,81].

Bermuda grass occurs in regions that receive more than 16 inches (410
mm) of rainfall a year.  In areas with less rainfall, it requires a
surface source of water or irrigation [75].  Bermuda grass is classified
as a facultative to facultative upland species [67].  In the
southwestern United States, Bermuda grass occurs in irrigated areas and
along streambanks [40,85].  Bermuda grass can expand a short distance
into the upland by transferring water via stolons. In a laboratory
study, Bermuda grass plants in separate moist and dry-soil compartments
transferred water from one compartment to the other [79].  In Organ Pipe
National Monument, Arizona, Bermuda grass occurs in damp areas but shows
no tendency to spread [6].

Bermuda grass has deep roots and is capable of extending roots during
drought stress.  Ten cultivars distributed at least some roots 47 to 59
inches (120-150 cm) deep during a drought stress laboratory test.  The
bulk of the root mass was within the top 24 inches (60 cm) [38].

Bermuda grass is susceptible to cold temperatures, especially those
occurring in the early winter.  Anderson and others [2] studied the
freeze tolerance of six cultivars grown in cone-tainers and held
overnight at freezing temperatures.  The temperature resulting in fifty
percent mortality ranged from 15 degrees Fahrenheit (-9.6 deg C) to 18
degrees Fahrenheit (-7.7 deg C) for the six cultivars [2].  A winter
hardy cultivar survived three winters in Morgantown, West Virgina, even
though temperatures reached as low as -8 degrees Fahrenheit (-22 deg C)
[53].

Bermuda grass is generally tolerant of low soil pH and high salt
concentration.  Six strains collected from southern Africa survived at
soil pH of 2.7 [26].  Vogel [81] reported Bermuda grass growing in soil
with pH as low as 3.2.  Bermuda grass dry matter yields were unaffected
by one growing season of irrigation with brackish water, but were
reduced in the second season [61].  Although tolerant of salty soils
[75,81], Bermuda grass does not appear to occur in saltwater wetlands.
It occurs only in the freshwater vegetation type in the Louisiana
coastal region [15].  Although common in the lower Sacramento River
valley, Bermuda grass does not occur in the tidal streambank community
[87].

In California Bermuda grass occurs below 2,950 feet (900 m) elevation
[40].  In Colorado it occurs from 4,200 to 5,300 feet (1,280-1,620 m)
elevation [20].  In Utah it occurs along waterways below 465 feet (1,525
m) [85].


SUCCESSIONAL STATUS : 
Bermuda grass is an early successional species.  Shade reduces Bermuda
grass vigor, and complete canopy closure may eliminate Bermuda grass
[14].  It inhabits open locations subject to frequent disturbances such
as grazing, flooding, and fire [21].  After a major flood in March on
the Hassayampa River in Arizona, Bermuda grass cover increased to near
preflood levels by September [73].  In a study of unreclaimed lignite
mines, Bermuda grass was most frequent on recently abandoned sites.  It
was not present on sites 20 years old or older [70].

On the Rio Grande Valley National Wildlife Refuge in southern Texas,
Rooseveltweed (Baccharis neglecta), buffel grass (Pennisetum ciliare),
and Bermuda grass were the dominant species after 5 years of old-field
succession.  The two grasses may have inhibited the establishment of
other species by successfully competing for moisture and light [83].

In central Utah, Bermuda grass was present in young saltcedar
communities (age 2 to 3.1 years) but was absent from older communities,
possibly because saltcedar lowers the water table [10].  Horton [42]
observed that spaces between individual saltcedar are usually dominated
by Bermuda grass or salt grass (Distichlis spicata) if the water table
is 5 feet (1.5 m) deep or less.


SEASONAL DEVELOPMENT : 
Bermuda grass begins growth late in the spring, continues to grow during
the hot summer months, and becomes dormant when the weather cools in the
fall [76].  Near Bakersfield, California, Bermuda grass emerged when
soil temperatures at a depth of 2 inches (5 cm) reached 63 degrees
Fahrenheit (17 deg C) [49].  In Morgantown, West Virginia, growth did
not begin until mid- to late May [53].  Bermuda grass flowers from July
to October [25].

Related categories for Species: Cynodon dactylon | Bermuda Grass