Achillea maritima

Overview

Achillea maritima, formerly Otanthus maritimus, is a perennial psammophyte of Mediterranean–Atlantic coastal dunes. A year-long field comparison recorded seasonal physiological differences from O. drummondii but did not measure root-zone salinity or impose a salt treatment. FloraVeg’s S = 3.8 is a relative ecological indicator. [S1, S3]

Names and classification

The accepted name is Achillea maritima (L.) Ehrend. & Y.P.Guo, formerly Otanthus maritimus. It is a perennial psammophyte of Mediterranean–Atlantic coastal dunes. [S1, S3]

The former name Otanthus maritimus remains common in ecological and experimental literature. [S1, S2, S3, S4]

Morphology and identification

This low perennial psammophytic herb has grey-white hairs, small leaves and dense flower heads, giving it a coastal-shrub-like appearance. Older ecophysiological studies commonly use the name Otanthus maritimus. [S1, S3, S6]

Distribution, habitat and phenology

Regional floras and field ecophysiology studies under the synonym document natural coastal dunes and sandy or gravelly beaches. FloraVeg also records mobile dunes and beach communities. These sources do not provide a salt-marsh or measured saline-root-zone locality for the species. Salt spray and coastal position alone do not establish saline root-zone conditions. [S1, S2, S3, S4]

The regional Asinara flora and Herbari Virtual record a local flowering period of June–August. This island/Mediterranean record is not a range-wide calendar and is not extrapolated from horticultural material. [S1, S6]

Zunzunegui et al. compared 15 pairs of neighbouring, similarly sized mature plants at Marismas del Odiel, Huelva, in November, February, April and July. Rainfall during May–October of the study year was only 44 mm. O. drummondii had higher assimilation in spring and summer, whereas A. maritima had higher photochemical efficiency. This was a seasonal field comparison on a dry coastal dune, without a salt treatment or root-zone salinity measurement. [S2]

Salinity in natural habitats

Floras and field studies found under the synonym chiefly describe mobile dunes and sandy or gravelly beaches. Relative ecological indices and coastal location do not measure salinity around the roots; a psammophyte is not automatically a halophyte. [S1, S2, S3, S4]

Salinity studies

FloraVeg.EU assigns the species a relative salinity-indicator value of S = 3.8. The value belongs to a community-ecology indicator scale; it is not a measurement of NaCl, soil ECe or water salinity. [S3]

Reported mechanisms and ecological adaptations

The year-long field comparison found seasonal differences in photosynthesis between the two dune species: A. maritima maintained higher photochemical efficiency, while O. drummondii had higher assimilation in spring and summer. The study did not measure ion responses or mechanisms under salt treatment. [S2]

Conclusions and evidence gaps

The available evidence places this species on coastal dunes and gravel beaches. A field ecophysiology study compared seasonal photosynthetic performance but did not manipulate or measure salinity. FloraVeg’s S = 3.8 is a regional relative indicator. Older studies use the former name Otanthus maritimus. [S1, S2, S3, S4]