Acacia cyclops

Overview

Acacia cyclops is an evergreen shrub of coastal scrub and dunes in Western and South Australia. In Craig et al.’s 12-week mixed-salt irrigation trial with saltland-source seedlings, survival was 100% at a final ECw of 9500 mS/m under salinity alone; weekly height measurements also showed slower growth as salinity increased. [S1, S2, S3, S93]

Names and classification

Acacia cyclops A.Cunn. ex G.Don. Craig et al. tested seedlings sourced from saline land in Western Australia; records of coastal dunes, scrub and salt-spray exposure describe habitats and do not place every population in saline root-zone soil. [S1, S3, S93]

POWO accepts Acacia cyclops A.Cunn. ex G.Don. The Craig et al. experiment is interpreted using the material and provenance reported in the paper. [S3, S93]

Morphology and identification

A coastal shrub whose adult leaves are mainly flattened phyllodes; its yellow flowers form globose heads, and mature seeds bear a conspicuous red aril. Fruit and seed characters can aid identification, but cultivated or naturalized plants should not be identified from locality alone. [S92]

Distribution, habitat and phenology

The Flora of Australia records the species from coastal scrub, sandy ground and dunes, and notes salt-spray tolerance; Craig et al. collected plants from naturally saline sites for a seedling trial. VicFlora also records naturalisation in South Africa, which does not describe the species' native Australian ecology. [S1, S2, S3, S93]

The available sources do not provide a flowering or fruiting season that can be corroborated across regions. [S93]

Salinity in natural habitats

Craig et al.’s material came from naturally saline sites in Western Australia, and the paper reports soil salinity at the collection sites. Coastal dunes and salt-spray exposure differ from salt-marsh root-zone conditions; the South African record is from an introduced range. [S1, S3]

Salinity studies

Craig et al. tested 3-month-old, nodulated seedlings sourced from Western Australia for 12 weeks. NaCl, MgSO4 and CaCl2 were mixed at a 16:3:1 molar ratio and increased weekly; the salinity-only irrigation reached a maximum ECw of 9500 mS/m, at which A. cyclops survival was 100%. The study also measured height weekly and shoot dry mass at harvest: height continued to increase through ECw of 7000 mS/m, with smaller increments at higher salinity. Mortality was higher in the separate salinity-plus-waterlogging treatment. [S1]

Craig et al.’s Table 2 reports source-site soil ECe by taxon. At the A. cyclops collection site, the 0–50 mm layer measured 6510, 80 and 130 mS/m in spring 1984, spring 1986 and autumn 1987, respectively; corresponding values for 200–400 mm were 2690, 80 and 400 mS/m, and for 400–600 mm were 4840, 260 and 1950 mS/m. Salinity at this site varied greatly by sampling year and depth; these values describe provenance, not seedling treatment concentrations. [S1]

eHALOPH transcribes Craig et al.’s 9500 mS/m ECw as 9.5 dS/m, but the correct conversion is 95 dS/m; the two values are not equivalent. The database also lists 9.7 dS/m linked to AbouDeya 1995, whose species-level material, methods and measurement metric have not been verified. [S2]

Reported mechanisms and ecological adaptations

Direct endpoints include survival, height and shoot dry matter, and the study shows that salinity and waterlogging jointly affect seedling performance. It did not test reproduction in mature plants or the full life cycle. [S1, S3]

Conclusions and evidence gaps

A. cyclops seedlings had 100% survival after 12 weeks of saline irrigation at a final ECw of 9500 mS/m, while weekly height measurements showed slower growth at higher salinity; this seedling trial does not address reproduction in mature plants. Craig et al.’s Table 2 also reports source-site ECe for this species, with large variation among years and depths. eHALOPH's conversion of 9500 mS/m to 9.5 dS/m is tenfold too low, and the measurement conditions behind its separate 9.7 dS/m entry remain unresolved. [S1, S2, S3, S4, S93]