Purple Viper's-Bugloss is an annual to biennial native to Europe and the Mediterranean. It was originally introduced in the U.S.A. and Australia in the 1800s as an ornamental plant, however, has since been declared as quite weedy and invasive in some Pacific coast states. It can be found growing in pastures, along with farm crops, along roadsides as well as in other disturbed areas such as gardens, open woodlands, and waste areas. It is spread by birds, livestock and the movement of various types of equipment such as farm vehicles and implements. It can also be spread by human or animal contact as well as by weather elements, like wind or rain. This erect annual lives up to its common names which include the words curse and plague. Considered weedy, this invasive plant is poisonous to grazing animals and called a threat to natural areas. The simple digestive system of a horse makes it especially hazardous to them. It contains pyrrolizidine alkaloids that can cause chronic liver damage and death in animals that consume it. Its threat to natural areas is a cause for concern as it produces an abundance of seeds that can quickly take over pastures and ranges, as well as crowding out other, more desirable plants. Unfortunately it is sometimes found as a contaminant in wildflower and commercial farm seed. Insects, Diseases, and Other Plant Problems: In addition to being poisonous to grazing animals, humans handling the plant can result in mild to severe skin irritation and hay fever.
Curated pairwise relationships between this plant and others in the library — who feeds
whom, who competes, who confuses the pests. Green reads as a good pairing, red as one to avoid.
No curated interactions recorded for this species yet.
Also noted by NC State
Related species the NC State Plant Toolbox flags for this plant — look-alikes to tell
apart, and plants that play a similar role in a planting. Ones we carry in the library are linked.
Full sun (6 or more hours of direct sunlight a day) | Partial Shade (Direct sunlight only part of the day, 2-6 hours)
Soil texture
Clay; Loam (Silt); Sand
Soil pH
Acid (<6.0); Alkaline (>8.0); Neutral (6.0-8.0)
Soil drainage
Good Drainage | Moist
Available space
12 inches-3 feet
NC region
Coastal; Mountains; Piedmont
Growth rate
Rapid
Maintenance
High
Form & Appearance
Habit / form
Erect; Mounding; Multi-stemmed
Texture
Coarse
Leaf color
Green
Leaf type
Simple
Leaf arrangement
Alternate
Leaf shape
Oblanceolate; Ovate
Leaf margin
Entire
Leaf feel
Soft
Leaf size
3-6 inches long, < 1 inch wide
Hairs present
Yes
Leaf detail
Plants form in a basal rosette of stalked leaves. These leaves have no stems. Each plant has two rounded seed leaves that can be found on short stalks. The first true leaves are also rounded and have a central vein.
Flower color
Blue; Pink; Purple/Lavender
Flower form
Cyme
Flower shape
Trumpet
Flower size
1-3 inches
Flower detail
The flowers can start out blue, turning purple and then pink. These trumpet shaped flowers each produce four brown or gray nutlet seeds which are surrounded by a husk covered in bristles. That gives them a fuzzy look. Flowers typically form on one side of the stem and have no stalks. Of the 5 stamens, 2 are significantly longer than the other 3.
Bloom time
Spring; Summer
Fruit color
Brown/Copper; Gray/Silver
Fruit type
Nut
Fruit size
< 1 inch long, < 1 inch wide
Fruit detail
The fruits are a cluster of 4 three-angled, oval nutlets that are gray, brown or black. They are marked with wrinkles and pitting.
Stem color
Green
Stem detail
Plants can be both single stemmed or multi-stemmed. They are covered with stiff hairs.