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- Adenocaulon
- N Adenocaulon bicolor — trail-plant
- Adiantum
- N Adiantum aleuticum — western maidenhair fern
- N Adiantum capillus-veneris — southern maidenhair fern
- N Adiantum pedatum — northern maidenhair fern, five-finger fern
- N Adiantum viridimontanum — Green Mountain maidenhair fern
- Adlumia
- N Adlumia fungosa — Allegheny vine, climbing fumitory
- Adonis
- X Adonis annua — pheasant's-eye
- Adoxa
- N Adoxa moschatellina — moschatel, muskroot, townhall clock
Read more about this topic: List Of Canadian Plants By Genus