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Pondweed
Potamogeton distinctus
ヒルムシロ
A perennial aquatic herb growing in rice paddies and ponds throughout Japan. It has two leaf types: ovate floating leaves on the water surface and linear submerged leaves. Wind-pollinated spicate inflorescences emerge above the water surface.
Identification Points
- ✓Dimorphic foliage: ovate floating leaves and narrow submerged leaves (heterophylly)
- ✓Slender spicate inflorescence erect above the water surface
- ✓Grows in rice paddies and ponds
Habitat
Rice paddies, ponds, and slow-flowing sections of rivers
Season
June–September (flowers)
Morphological TraitsAI-estimated, needs verification
Growth form
Herb
Leaf shape
Linear
Habitat
Aquatic
Leaf type
Simple
Leaf margin
Entire
Petal count
4 petals
Petal fusion
Free
Leaf dissection
Undivided
Flower symmetry
Actinomorphic
Ovary position
Superior
Plant sex
Hermaphrodite
Phylogenetic Positionヒルムシロ科 →
Phylogenetic Position
Angiosperms > Monocots > Alismatales > Potamogetonaceae
Divergence Era
Latest Cretaceous to Paleogene (ca. 70 Ma onwards)
Evolution Notes
Potamogetonaceae represents a group of aquatic plants that re-adapted to aquatic life from terrestrial ancestors. The dimorphic leaves (floating and submerged) demonstrate a sophisticated adaptation utilizing both underwater and surface environments.
View on evolution timeline →Sources & References
AI-generated, needs verification