Zannichellia palustris
Zannichelliaceae
common poolmat, horned-pondweed
horned-pondweed family
to 50 cm × 0.2–0.6 mm.
3.5–4.2 cm × 0.2–1 mm, apex acute.
alternate, opposite, or pseudowhorled, often all on same plant, submersed, sessile;
sheath not persisting longer than blade, not leaving circular scar when shed, ligulate, not auriculate;
blade linear;
intravaginal squamules scales, 2.
axillary, cymes, without subtending spathe, sessile.
uniasexual, staminate and pistillate flowers on same plant; subtending bracts absent;
perianth absent.
filament 1.5–2 mm, connective prolonged into blunt tip 0.1 mm.
stamens 1;
anther dehiscing longitudinally;
pollen globose.
pistils 4–5;
style 0.4–0.7 mm.
pistils (1–)4–5(–8), distinct, short-stipitate;
ovules pendulous, anatropous.
1.7–2.8 × 0.6–0.9 mm;
rostrum 0.7–2 mm;
podogyne 0.1–1.5 mm;
pedicel 0.3–1.2 mm.
drupaceous.
1;
embryo curved.
Zannichellia palustris
Zannichelliaceae
Outside of Europe most Zannichellia are considered to be Z. palustris (W. Van Vierssen 1982). In Europe three species have been recognized based on stamen length, fruit length, podogyne length, and the rostrum to fruit length ratio. For Z. palustris in Europe the mean rostrum length is 0.78 ± 0.20deletion} mm, the mean podogyne length is 0.4 ± 0.19 mm, and the rostrum to fruit ratio is less than 0.5 (W. Van Wierssen Vierssen 1982). North American Zannichellia does not match any of these figures exactly. In North America Zannichellia has been considered historically to comprise only one species, which has been called Z. palustris. Until further research determines the range of Zannichellia and species delimitations, we areI am continuing to consider all North American material to be monospecific and am are applying the name Z. palustris to our that material.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Genera 4, species 10–12 (1 genus, 1 species in the flora).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
- Local floras:
BC, 
CA, 
OR, 
WA - Local Web sites: CalFlora, CalPhotos,
Flora NW, 
Go Botany, 
IL Wildflowers, 
KS Wildflowers, 
LA Plants, 
MD Biodiversity, 
MI Flora, 
MN Wildflowers, 
MO Plants, 
PNW Herbaria 
WildflowerSearch
iNaturalist (observations)
USDA Plants Database- LBJ Wildflower Center
- SEINet
- Plants of the World Online
- Encyclopedia of Life
- Wikipedia
- Google Image Search
- Local floras: CA, OR
- Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria
- WildflowerSearch
- iNaturalist (observations)
- LBJ Wildflower Center
- SEINet
- Plants of the World Online
- Encyclopedia of Life
- Wikipedia
- Google Image Search
