Cynoglossum is a genus of flowering plants in the Forget-Me-Not family, Boraginaceae. There are a number of species that are commonly known as houndstongue. Some are cultivated for their small flowers, while Cynoglossum officinale is an invasive species in Europe and North America. Like other species, it contains toxic alkaloids and has been reported to cause poisoning of horses, cattle, and sheep. This weed is the subject of much research, mostly into methods of containment.
The most frequently grown ornamental species is Cynoglossum amabile, more commonly known as Chinese Forget-Me-Not. This species is grown under varying conditions, depending on what part of the world it is being grown in. For more cool climates, such as the Pacific Northwest of the United States, this type of Forget-Me-Not is grown in the sun. In warmer climates, it can be grown in part shade.
The original species had blue flowers, but varieties have been developed with white and pink flowers. The plants generally grow to 1.5-2 ft (0.45-0.6 m) tall. They are considered drought-tolerant in climates that receive a lot of rain. In desert areas, they usually require additional watering. One advantage of these plants is that, due to the toxic chemicals they contain, deer do not eat them.
Although the plant is a biennial, Chinese Forget-Me-Not is generally grown from seeds, as an annual. In cool regions, they are planted in late spring for summer bloom. In contrast, the seeds are planted in the fall for winter bloom in more tropical climates. The plants are typically spaced one foot (0.3 m) apart. They will frequently self-seed and create new plants.
An alternate name for Chinese Forget-Me-Not is Chinese houndstongue. The Cynoglossum plants are called houndstongues from older folklore. There was once a belief that having a leaf in the heel of one’s shoe would prevent attacks from dogs.
Houndstongue generally refers to the aggressive weed Cynoglossum officinale. This plant is originally from Europe and was accidentally introduced into North America. It is an official invasive plant according to the United States Department of Agriculture (USDA), and will grow in a variety of soils. There are many measures undertaken to prevent houndstongue from growing in pastureland.
The plant can be a biennial, or a perennial that does not live for many years. The stems that produce flowers grow to between 1 and 4 ft (0.3 to 1.2 m) tall. Each plant produces up to 800 seeds containing four nutlets, with all of the small nuts having prickles with barbed tips. These attach themselves to the fur of animals or the clothing of people. This can help to spread the plant great distances.
This species of Cynoglossum will grow in a wide range of soils, although it is generally not a problem in cultivated fields. Initial attempts to hinder its spread usually focus on preventing this weed from becoming established. Subsequent efforts may utilize soil-tilling, but the plants can have taproots greater than three feet (0.9 m) deep. Burning and herbicide treatment are other methods of attempted control. In Canada, two types of beetles that attack the roots of the plants have been introduced as a method of biological control.