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Horsetail She-oak
Casuarina equisetifolia
γγ―γ΅γγ’γ―γγͺγ¦
An evergreen tall tree growing on tropical and subtropical coasts, planted and naturalized in Okinawa. The leaves are reduced to scales, and slender green jointed branchlets (cladodes) perform photosynthesis, resembling Equisetum. Root nodules with nitrogen-fixing bacteria enable growth in nutrient-poor soils.
Identification Points
- βLeaves are reduced to tiny scales; green, slender, jointed branchlets (cladodes) photosynthesize
- βResembles conifers or Equisetum in appearance but is an angiosperm
- βBears woody, cone-like fruits (pseudocones)
Habitat
Tropical and subtropical coasts (planted and escaped in Okinawa)
Season
Year-round (evergreen)
Morphological TraitsAI-estimated, needs verification
Growth form
Tree
Evergreen/Deciduous
Evergreen
Habitat
Coastal
Leaf arrangement
Whorled
Leaf type
Simple
Petal count
3 petals
Petal fusion
Free
Stipules
Absent
Ovary position
Superior
Phylogenetic Positionγ’γ―γγͺγ¦η§ β
Phylogenetic Position
Angiosperms > Eudicots > Core eudicots > Fagales > Casuarinaceae
Divergence Era
Paleogene (about 50β40 million years ago)
Evolution Notes
Casuarinaceae displays convergent evolution where leaves are reduced and stems become the primary photosynthetic organs. Symbiosis with nitrogen-fixing root nodule bacteria is widespread in the family, contributing to adaptation to nutrient-poor coastal soils.
View on evolution timeline βSources & References
AI-generated, needs verification