Common name: Blue Lace-flower or Rottnest Island Daisy
Trachy - from the Greek trachys, rough; mene, moon
coerulea – deep sky-blue
Erect annual herb, with coarse glandular hairs, growing to about 0.2-1 m x 0.2-0.8 m. Flowers are predominantly pale to deep blue in wide umbels to 6 cm across, many-flowered, terminal on hairy stalks to 20 cm long. Stems solitary, leaf blades broadly ovate in outline and deeply divided into segments. The typical subspecies leucopetala is a white flowering form of similar habit and cultivation requirements.
Common and widespread from Dongara to Augusta. Along the Perth coast on limestone and dunes extending inland into forest and woodland areas and on off-shore islands particularly Rottnest and Garden Island where the species is locally abundant. The subspecies leucopetala is not as commonly distributed, being limited to the Geraldton Sandplains and Central West Coast regions.
Refer to the distribution map for this species via the Department of Environment and Conservation’s FloraBase online herbarium.
October to January.
Adapts readily to cultivation in freely draining acidic or slightly alkaline soils, in full sun to semi-shaded sites. Young plants need to have moist soils in order to achieve sturdy growth. Tip pruning will encourage flowerhead production and regular applications of a weak-strength liquid fertiliser can also be beneficial in promoting growth and flowering.
Propagation is from seed sown in May/June. Seed may be sown in seed trays and pricked out when small (two leaf stage) or direct-sown into the garden. When small, some protection from snails will need to be in place.
Pests and Diseases
This plant can sometimes be susceptible to stem borers which attack the young flowering stems; however, this is not common.
View in Kings Park
This species can be found at the entry to the Western Australian Botanic Garden and in the gardens surrounding Zamia Cafe (refer to map).
In Kings Park, Trachymene is sown in beds with other late flowering annuals such as Xerochrysum bracteatum, Podolepis and Waitzia species. Trachymene will bring height to flower displays and blooms in succession to Rhodanthe if sown at the same time (May/June). If taking a drive up the coast at this time of year, it can be seen flowering between Perth and Jurien Bay.