Invasiveness Assessment - Blue hound's tongue (Cynoglossum creticum) in Victoria

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Plant invasiveness is determined by evaluating a plant’s biological and ecological characteristics against criteria that encompass establishment requirements, growth rate and competitive ability, methods of reproduction, and dispersal mechanisms.

Each characteristic, or criterion, is assessed against a list of intensity ratings. Depending upon information found, a rating of Low, Medium Low, Medium High or High is assigned to that criterion. Where no data is available to answer a criterion, a rating of medium (M) is applied. A description of the invasiveness criteria and intensity ratings used in this process can be viewed here.

The following table provides information on the invasiveness of Blue hound's tongue.

A more detailed description of the methodology of the Victorian Weed Risk Assessment (WRA) method can be viewed below:

Victorian Weed Risk Assessment (WRA) method (PDF - 630 KB)
Victorian Weed Risk Assessment (WRA) method (DOC - 1026 KB)
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Common Name: Blue hound's tongue
Scientific name: Cynoglossum creticum

Question	Comments	Rating	Confidence
Establishment
Germination requirements?	Germinates in autumn and flowers in spring-summer (CRC for Australian Weed Management 2003). Requires natural seasonal conditions.	MH	M
Establishment requirements?	No information available regarding C. creticum although C. officinale (the most closely related species which is also biennial herb found in same habitats) is shade tolerant and can occur in areas of thick litter accumulation (USFS 2003). As C. creticum can also occur in open woodlands, assume it too can establish under a moderate canopy.	M	MH
How much disturbance is required?	Invades grasslands. Most commonly grows on disturbed sites such as roadsides, sand dunes or open woodlands, where it establishes and spreads quickly’ (CRC for Australian Weed Management 2003). Although prefers disturbed sites, can establish in minor disturbed natural ecosystem.	MH	M
Growth/Competitive
Life form?	A biennial herb (USFS 2003) – life form – other.	L	MH
Allelopathic properties?	None described in USFS 2003.	L	MH
Tolerates herb pressure?	‘ leaves contain pyrrolizidine alkaloids that kill cattle and horses. ‘.. insects tend to avoid the plant because of the alkaloids in its leaves’ (CRC for Australian Weed Management 2003). Favoured by heavy grazing as not eaten by animals	H	M
Normal growth rate?	‘Invades grasslands and suppresses native grasses’. ‘Seedlings are fast growing’ (CRC for Australian Weed Management 2003). Assume that plant will equal competitive species of same life form.	MH	M
Stress tolerance to frost, drought, w/logg, sal. etc?	‘Fire probably top-kills hounds tongue plants’ (CRC for Australian Weed Management 2003). C. officinale, a closely related species, does not tolerate waterlogging and is frost susceptible (USFS 2003). Insufficient information available on C. creticum. Score as medium	M	MH
Reproduction
Reproductive system	‘Spreads by seeds’ (CRC for Australian Weed Management 2003). Does not vegetatively reproduce. No evidence in literature to suggest if self or cross-pollinates.	L	M
Number of propagules produced?	‘ .. mature plants each producing several hundred [seeds]’ (CRC for Australian Weed Management 2003). Likely that plant produces between 50 to 1,000 propagules per flowering event.	ML	M
Propagule longevity?	‘Plant dies after flowering, but seeds may stay attached until the following spring, delaying germination for a year’ (CRC for Australian Weed Management 2003). Viability is two to three years.	L	M
Reproductive period?	‘Lifecycle that is completed in two years or seasons, with the second season usually devoted to flowering and fruiting’ (CRC for Australian Weed Management 2003).	ML	M
Time to reproductive maturity?	‘Lifecycle that is completed in two years or seasons, with the second season usually devoted to flowering and fruiting’ (CRC for Australian Weed Management 2003).	MH	M
Dispersal
Number of mechanisms?	‘In North America cattle and wildlife are important dispersers of the closely related C. officinale .. likely also to be the case in Australia’ (CRC for Australian Weed Management 2003). ‘Seeds may be transported by animals or people into disturbed areas where they find suitable conditions for germination.’	ML	M
How far do they disperse?	‘Spread long distances attached to people or animals’ (CRC for Australian Weed Management 2003). Very likely that some propagules will disperse greater than 1 km.	H	M

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