Hierarchy classification:

1. top of the aat hierarchies
2. Agents Facet
3. Living Organisms (hierarchy name)
4. living organisms (entities)
5. Eukaryota (domain)
6. Plantae (kingdom)

Anotations

Scope note:

Cryptogamous (using sexual reproduction but lacking stamens or pistils) with hollow, jointed stems and whorls of slender branches at the joints. Today comprises one genus and around 30 species, but they were abundant in earlier periods; some Paleozoic sphenophytes grew up to 100 feet in height.