Blue hound's tongue

Appearance

Blue hound’s tongue is a biennial plant which grows up to 600 mm high. Its stems are densely covered with fine hairs. It has dark-green leaves, up to 200 mm long and 25–35 mm wide, covered with long coarse hairs. The base of the leaf is heart-shaped and clasps the stem. The leaves are alternately placed and decrease in size up the stem. Blue hound’s tongue has a long taproot which is used to store energy reserves.
In the first year of growth, blue hound’s tongue forms a rosette; this is followed by one or more tall flowering stems during the second growing season. The flower, a 10–11 mm long tube, is pink to blue and has darker hairless veins and stamens growing from the base of the tube. Each flower produces four ‘nutlets’ covered with short, hooked or barbed prickles when mature. The seeds are oval and 6–8 mm long, and their outer surface is thickly covered with prickles.

Naming

Synonyms
Cynoglossum pictum Ait.

Distribution

Native to southern Europe (i.e. France, Spain, Portugal, Italy, Albania, Greece and Bulgaria).
This species has a limited naturalised distribution in the coastal districts of southern New South Wales (i.e. in the Eden district).
Naturalised overseas in South America (i.e. Argentina and Chile).

Status

Blue hound’s tongue is on the Alert List for Environmental Weeds, a list of 28 non-native plants that threaten biodiversity and cause other environmental damage.
Although only in the early stages of establishment, these weeds have the potential to seriously degrade Australia’s ecosystems.
Blue hound’s tongue is a biennial herb that has been reported to be a problem weed in Argentina and Chile. It could cause problems if it becomes established in Australia as its leaves are toxic to livestock. It was first recorded in Sydney, New South Wales, in 1898. In 1933 a naturalised population was noted in Eden, NSW, and its presence was confirmed until 1976. Two new infestations have been recorded in 2004 upstream from Eden, along the Towamba River. At least one other closely related species, C. officinale (hound’s tongue), is a troublesome pasture weed, particularly in Canada and northern central United States. It invades grasslands and
suppresses native grasses. Like blue hound’s tongue, this plant has burrs that attach to cattle, causing irritation.

Habitat

Blue hound’s tongue is a fairly typical plant of nutrient-rich Mediterranean to warm temperate grassland communities which occur at altitudes of 0–1000 m.
It is a native of southern Europe.

Reproduction

Blue hound’s tongue is a biennial plant, ie it has a life cycle that is completed in two years or seasons, with the second season usually devoted to flowering and fruiting.
It germinates in autumn and flowers in spring–summer. The stimulus for flowering is a combination of summer moisture, rosette size and vernalisation (exposure to a period of low temperatures). The rosettes may not flower, but pass the winter to flower in the following year. The plant dies after flowering, but seeds may stay attached until the following spring, delaying germination for a year.