The Ecology of the Seagrasses of South Florida - USGS National ...

(4) The ability to complete their systematic treatments such as den Hartog
reproductive cycle while fully (1970) and Tomlinson (1980) should be consubmerged
. sulted, however, when comparing the seagrasses
of other areas. The best descrip-
(5) The ability to compete with
other organism in the narine
tions of the local species are still to he
found in Phil1 ips (1960).
environment.
Turtle grass (Thal assia testudinum)
Only a small, closely related group of is the largest and most robust of the
monocotyledonous angiosperms have evolved south Florida seagrasses. Leaves are riball
of these characteristics. bon-like, typically 4 to 12 rnm wide with
rounded tips and are 10 to 35cm in length.
h'orldwide there are approximately 45 There are commonly two to five leaves per
species of seagrasses that are divided short shoot. Rhizomes are typically 3 to
between 2 famil ies and 12 genera. The 5 m wide and may be found as deep as
Potamogetonaceae contains 9 genera with 34 25 cm (10 inches) in the sediment. Thalas-
species, while the family Hydrochari taceae sia forms extensive meadows throughout
has 3 genera and 11 species (Phillips most of its range.
1978). In south Florida there are four
genera and six species of seagrasses Manatee grass (Syringodium f il ifome)
(Table 2). The two genera in the family is the nost unique of the local seagrass-
Potanogetonaceae have been reclassified es, as the leaves are found in cross seccomparatively
recently and many of the tion, There are commonly two to four
widely quoted papers on the south Florida leaves per shoot, and these are 1.0 to 1.5
seagrasses show Qmodocea for Syrinaodiurn mm in diameter. Length is highly variand
Dipfanthera for Halodule. Recent dis- able, hut can exceed 50 cm (20 inches) in
cussion in the literature speculates on some areas, The rhizome is less rohust
the possibility of several species of than that of Thalassia and more surfici-
Halodule in south Florida (den Hartog ally rooted. Syringodium is covmonly
=70), but the best current evidence mixed with the other seagrasses, or in
(Phillips 1967; Phillips et al. 1374) in- small, dense, monospecific patches, It
dicates only one highly variable species. rarely foms the extensive meadows 1 ike
Thal assi a.
The small species numher (six) and
di sti nctivc appearance of south Florida Shoal grass (Halodule wrightii) is
seagrasses make a standard dichotonous key extremely important as an early colonizer
generally unnecessary (Figure 4). General of disturbed areas. It is found primarily
Table 2. Sea?rasses of south Florida.
-.- --
Family and species
Hydrochari taceae
Conmon name
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