92
Josef Daniel Ackerman
Table 2. (Cont.)
Reproductive ecology
Staminate flower
Carpellate flower
Diaspore
Genus (# sp)
Mode
Dicliny
Arrangement
Anthers
Pollen (dimensions) Exine
Carpels
Texture
Fruit
Seed
Zannichelliaceae
a
Zannichellia (1) Submarine Monoecious 1–2 flowers in
leaf axil
Naked with 1–2
theca
Spherical
(23–28
µm)
Present Group of
funnelshaped
stigmas
Non-papillate Achene, dorsal
ridge
No endosperm
Ruppiaceae
a
Ruppia (2–10)
Surface
Monoecious Inflorescence
2 stamens
Chevron (90
×
30
µm)
Present Number of
funnelshaped
stigmas
Non-papillate Achene
No endosperm
Posidoniaceae
Posidonia (9)
Submarine Bisexual
Bisexual flowers
on cymose
inflorescence
3 stamens
Filiform
(500–1000
µm)
Absent 1 carpel with
discshaped
lobed
stigma
Non-papillate Fleshy, free
floating
Not dormant,
no
endosperm,
elliptical
Zosteraceae
b
Heterozostera
(1)
Submarine Monoecious Unisexual on
inflorescence
(spathe-spadix)
1 stamen with 2
free thecae,
long
retinacules
Filiform
Absent 1 carpel with
2 stigmas
Non-papillate Ovoid–
ellipsoidal
Dormant, no
endosperm,
finely
striated
Phyllospadix (5) Submarine
and
surface
Dioecious
Unisexual on
inflorescence
(spathe-spadix)
1 stamen with 2
free thecae,
retinacules
Filiform
(1500
µm)
Absent 1 carpel with
2 stigmas
Non-papillate Crescent shaped
with fibrous
endocarp
Dormant, no
endosperm,
Nanozostera (8) Submarine
and
surface
Monoecious Unisexual on
inflorescence
(spathe-spadix)
1 stamen with 2
free thecae,
short
retinacules
Filiform
Absent 1 carpel with
2 stigmas
Non-papillate Ellipsoid
Dormant, no
endosperm,
smooth,
ribbed,
ridged
Zostera (4)
Submarine
and
surface
Monoecious Unisexual on
inflorescence
(spathe-spadix)
1 stamen with 2
free thecae, no
retinacules
Filiform (2700
×
7.5
µm)
Absent 1 carpel with
2 stigmas
Non-papillate Ellipsoid
Dormant, no
endosperm,
smooth,
ribbed,
ridged
a
Taxon included for comparative purposes (i.e. not always considered a seagrass).
b
Note that Les et al. (2002) recommend collapsing Heterozostera and Nanozostera into Zostera.