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River-weed family
Podostemaceae
カワゴケソウ科
A family of highly specialized aquatic plants that grow attached to rocks in rapids and waterfalls. The plant body is flattened and moss-like or alga-like, with indistinct differentiation of roots, stems, and leaves. Several species including Cladopus japonicus occur in Japan. About 50 genera and 270 species are distributed in tropical rapids.
Key Characteristics
- ●Propagates via flattened thalloid structures (root-like bodies) attached to rocks
- ●Extremely reduced morphology with indistinct root, stem, and leaf differentiation
- ●Aquatic plants specialized for rheophytic (rock-attached) growth in rapids and spray zones
- ●Many species die as annuals in the dry season and germinate after water levels recover
Morphological Traits
A family may include species with different trait values — multiple values indicate the range within the family.
Leaf arrangement
Alternate
Leaf type
Simple / Compound
Venation
Pinnate
Leaf margin
Entire
Growth form
Herb
Evergreen/Deciduous
Deciduous
Latex
Present / Absent
Flower symmetry
Actinomorphic / Zygomorphic
Petal count
3 petals / 5 petals / 6 petals / Many
Ovary position
Superior
Plant sex
Hermaphrodite
Phylogenetic Position
Angiosperms > Eudicots > Core eudicots > Malpighiales > Podostemaceae
Divergence Era
Paleogene (about 40–30 million years ago)
Representative Genera
Related Evolution Events
- ・Extreme body plan transformation for rheophytic rock-attached life (flattening and organ fusion)
- ・Evolution of the most aberrant vegetative body morphology among angiosperms
Plants in River-weed family on this site
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