Montbretia (Crocosmia x crocosmiiflora)

Photo: (c) Forest and Kim Starr

Family:  Liliaceae

Growth Habit: An upright herbaceous plant with short-lived foliage that grows each year from long-lived underground ‘bulbs’. Its strap-like, soft, hairless leaves, 6-12 per’ bulb’, 30-80 cm long and 1-2 cm wide, are mostly clustered near the base of the plant and sheath the stem. The ‘bulbs’ or corms are 10-35 mm across, rounded or flattened and covered in several brown fibrous layers. Flowers are borne in elongated clusters in two rows along the zig-zagging branches at the top of green, rounded, erect stems. Each branch is 15-30 cm long and has 4-20 flowers.

Type of Plant: Upright perennial lily.

Photo: (c) Sabencia Guillermo César Ruiz CC International License

Flowers: Yellow to orange-red (usually orange-red with yellow centres) with 6 ‘petals’ that are fused together at the base into a tube 12-18 mm long. They have three stamens and a style that splits into three short branches, about 4 mm long, near its tip, each topped with a stigma. Flowering occurs mostly during summer and autumn, but also during spring in warmer climates.

Fruits/Seeds: The fruit are three-lobed capsules, 5-10 mm long, that turn from green to brown, and become shrivelled, as they mature. Seeds are usually not produced, but when present they are brown or reddish-brown in colour and flattened or triangular in shape about 3 mm long and 1-2 mm wide.

Crocosmia corm. Photo: (c) Velela GFDL, CC-BY 3.0 licenses

Dispersal: New plants develop from the tips of the creeping underground rhizomes, which are produced by the corms. Long range dispersal is via rhizomes, corms and seeds (when produced), which are carried by water, contaminated soil, machinery or dumped garden waste.

Distribution: A common garden escapee, it inhabits wetter grasslands, open woodlands, pastures, waterways, gardens, roadsides, waste areas, disturbed sites and railway enclosures. Found throughout the Tamar, particularly on roadsides in the East and West Tamar.

Status: Not declared in Tasmania but has the potential to be a significant environmental weed.

Weed Impacts:

  • Invasive in moist forests, roadsides, drainage lines and waterways.
  • Competes strongly, and displaces native vegetation moving quickly along waterways and roadsides and then outwards into nearby bushland.
  • Degrades riparian native vegetation and habitat.
  • Crowds out understorey species and impedes germination of tree and shrub species.
  • Significantly modifies habitat value for a range of species.

Control Methods:

  • Do not dump garden waste or soil. Dispose of all weed material, especially corms, appropriately, do not put in home compost heaps.
  • Ensure soil is clean when moving between sites.
  • Undertake appropriate hygiene practices for machinery, tools and equipment.
  • Manual Removal. Small infestations can be manually dug out when soil is wet. Ensure you dig deeply and remove all the corms to stop regrowth occurring.
  • Herbicide. Wipe leaves or spot spray in spring when plant is growing. Herbicides to use are glyphosate or metsulphuron methyl.

N.B. Always check the herbicide label before use.