Hornwort
Ceratophyllum demersum
マツモ
A submerged aquatic plant growing in ponds and rice paddies. It has no roots and grows drifting in the water. Whorled leaves with dichotomously forked, stiff linear segments are characteristic. Widely used as an aquarium plant (hornwort or goldfish weed).
Identification Points
- ✓Rootless, growing entirely suspended in water
- ✓Leaves in whorls of 4–8, linear and 1–2 times dichotomously forked
- ✓Short internodes give the plant a dense, yarn-like appearance
Habitat
Ponds, rice paddies, reservoirs, and slow-flowing sections of rivers (submerged)
Season
Year-round
Morphological TraitsAI-estimated, needs verification
Growth form
Herb
Leaf arrangement
Whorled
Leaf shape
Linear
Habitat
Aquatic
Petal count
Many
Petal fusion
Free
Stipules
Absent
Leaf dissection
Dissected
Flower symmetry
Actinomorphic
Ovary position
Superior
Plant sex
Monoecious
Phylogenetic Positionキンギョモ科 →
Phylogenetic Position
Angiosperms > Ceratophyllales > Ceratophyllaceae (positioned near the base of eudicots)
Divergence Era
Early to Mid-Cretaceous (about 120–100 million years ago)
Evolution Notes
Ceratophyllaceae is one of the most basal angiosperm lineages (more basal than Magnoliids). It has undergone extreme specialization including loss of roots and fully aquatic life, with pollen released underwater and drifting beneath the surface for pollination.
View on evolution timeline →Sources & References
AI-generated, needs verification