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Common Rush
Juncus effusus var. decipiens
イグサ
A perennial growing in rice paddies and wetlands. The cylindrical stems contain a spongy pith and have been used to make tatami mat coverings, rush mats, and woven baskets. It is an essential plant underlying Japan's tatami culture.
Identification Points
- ✓Stems are cylindrical and erect, with a white spongy pith in cross-section
- ✓Inflorescence appears to emerge from the middle of the stem (the bract looks like a continuation of the stem)
- ✓Leaves are reduced to sheaths clasping the stem base
Habitat
Rice paddies, wetlands, and ditch margins
Season
June–August (flowers)
Morphological TraitsAI-estimated, needs verification
Growth form
Herb
Habitat
Aquatic
Leaf arrangement
Alternate
Leaf type
Simple
Venation
Parallel
Petal fusion
Free
Leaf dissection
Undivided
Flower symmetry
Actinomorphic
Ovary position
Superior
Phylogenetic Positionイグサ科 →
Phylogenetic Position
Angiosperms > Monocots > Poales > Juncaceae
Divergence Era
Late Cretaceous to Paleogene
Evolution Notes
Juncaceae is a monocot lineage specialized for wind pollination, with small and inconspicuous tepals.
View on evolution timeline →Sources & References
AI-generated, needs verification