Short description of Crocosmia pottsii x aurea = C. x crocosmiiflora, Montbretia

It forms clumps similar in appearance to those of the yellow iris, but with bright orange flowers. There are several related species and hybrids.

Impact summary: Crocosmia pottsii x aurea = C. x crocosmiiflora, Montbretia

The impact on vegetation is low, as it persists but spreads only slowly if at all. There are no known harmful effects to humans or animals.

Habitat summary: Crocosmia pottsii x aurea = C. x crocosmiiflora, Montbretia

Usually in woodland edges or on roadsides where garden refuse has been dumped.

Overview table

Environment	Terrestrial
Species status	Hybrid GB
Native range
Functional type	Land plant
Status in England	Hybrid GB
Status in Scotland	Hybrid GB
Status in Wales	Hybrid GB
Location of first record	v.c.83
Date of first record	1907

Origin

It is a horticultural cross derived (in France) from species brought originally from South Africa.

First Record

Introduced to gardens in 1880 and first recorded in the wild in 1911.

Pathway and Method

Very commonly grown in gardens, where it tends to spread and form large clumps. Many gardeners dump the excess plants on roadsides and in woods.

Species Status

It is mildly invasive in the west of GB, especially on coastal slopes and on hedgebanks in Cornwall. In Ireland it is much more widespread in similar habitats, and in New Zealand it is considered an 'environmental weed.'

Dispersal Mechanisms

Reproduction by seed is unusual, so most spread is by gardeners. Once established, clumps grow vegetatively, sometimes forming large colonies.

Reproduction

A monoecious plant, occasionally producing viable seed. More commonly reproducing by producing rhizomes that give rise to new corms a short distance form the parent plant.

Known Predators/Herbivores

Montbretia is highly resistant to pests and does not suffer serious herbivory.

Resistant Stages

All stages are resistant to pests and herbivory.

Habitat Occupied in GB

Mostly roadsides and woodland edges, as it can tolerate only partial shade. It is more abundant in western parts, as it is susceptible to severe frost, and it is typical of hedgebacks and coastal habitats, including the upper reaches of saltmarshes.

Widespread throughout GB, mainly in urban areas and close to the west coast.

Environmental Impact

Cornwall Wildlife Trust suggested that montbretia 'pushes out native flowers'.

Health and Social Impact

There are no adverse impacts from Montbretia, but it is a popular feature of hedgebanks owing to its colourful flowers.

Economic Impact

None known.

Identification

Stace, C.A. (2010) New flora of the British Isles, Third Edition, Cambridge University Press, Cambridge.

Plantfinder: http://www.bbc.co.uk/gardening/plants/plant_finder/

Biology, ecology, spread, vectors

Howell, C. (n.d.) Consolidated list of environmental weeds in New Zealand. http://www.doc.govt.nz/upload/documents/science-and-technical/drds292.pdf.

Management and impact

http://news.bbc.co.uk/1/hi/england/cornwall/6577593.stm

General

Chater, A.O. (2010) Flora of Cardiganshire, Aberystwyth.