Stinking iris
Botanical Name
Iris foetidissima
Family
Iridaceae (iris)
Where is it originally from?
Europe, Asia, North Africa
What does it look like?
Clump-forming perennial (<80 cm) with red-brown rhizomes (<15 mm diameter). Leathery, dark green leaves (15-25 mm x 60-100 cm) are broad, sword-shaped, and foul-smelling when crushed. Erect flowering stems (60-80 cm) with dull yellow flowers (<10cm diameter, Nov-Dec) with greenish-brown markings (occasionally brownish-purple) are followed by green, 3-sided seed capsules (5 cm long) that split open to release many round, scarlet seeds (5 mm diameter).
Are there any similar species?
Many Gladiolus and related species, and four other exotic Iris species, all of which have been found in the wild, are similar. I. pseudacorus is the only aquatic species with tall stems and yellow flowers.
Why is it weedy?
Tolerant of deep shade, hot or cold, most soil types and drought and semi-damp conditions. Disperses widely and forms dense long-lived clumps. Unpalatable and toxic to livestock and recovers from damage.
How does it spread?
Birds spread the seeds, and rhizome fragments are spread by water. Both are spread by contaminated machinery, soil and dumped vegetation. Often found on roadsides and wasteland.
What damage does it do?
Smothers the ground, preventing the establishment of native plant seedlings. Poisonous seeds may affect birdlife.
Which habitats is it likely to invade?
Heavily disturbed forest and margins, shrubland, fernland, bare ground and gullies.
What can I do to get rid of it?
1. Physical removal (all year round) - Dig out entire plant - Ensure all plant material is dipsosed of to refuse, burnt or buried deeply to prevent regrowth. If using weedmat, cut tops and cover at least 3-4 months.
2. Cut and paste - Cut the stem/trunk as close to the ground as possible and cover the entire stump with herbicide as soon as possible after cutting. Apply glyphosate gel (120g/L strength) to the entire cut stem.
3. Foliar spray (spring to autumn) - Apply herbicide using a hand-held sprayer/knapsack. Apply a mix of Glyphosate (360 g/L active ingredient) herbicide at 15ml/L + metsulfuron herbicide (600g/kg active ingredient) at 0.3g/L + an organo silicone penetrant at 3ml/L and thoroughly wet all parts of plant. Note: Overspray will kill other (desirable) broadleaf plants and has residual activity in the soil which aids in killing below ground parts. Do not use over or near water bodies or wetlands and use only as directed on label.
CAUTION: When using any herbicide or pesticide, PLEASE READ THE LABEL THOROUGHLY to ensure that all instructions and directions for the purchase, use and storage of the product, are followed and adhered to.
What can I do to stop it coming back?
Bared areas, both shady and open, can be reinfested from the seed bank, and rhizomes can resprout, hard to kill. Exclude livestock at all times. Remove seeds if ripe, dispose. Replant with taller understorey species in forest sites, to minimise seedlings.
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