Class B Noxious Weed
- As with many plants grown for agricultural or horticultural purposes, there are several subspecies and cultivars of yellow archangel, because most subspecies share many invasive characteristics; yellow archangel is inclusive of all its subspecies and cultivars.
- Popular choice for ground coverage, especially in shady areas, this plant is also used in hanging baskets and flowerbeds because of its silvery foliage.
- Native to temperate regions of Asia and Europe.
- Semi-evergreen to perennial, fast growing, viny, herbaceous plant that grows prostrate to the ground, forming a dense ground cover and also climbing up and over low-growing vegetation and small structures such as tree stumps.
- In bright sun, the plant will grow more erect and leaves are typically thicker, brighter and larger than shade leaves.
- Leaves are oppositely arranged on a purplish, square-shaped, hairy stem.
- Leaves are serrated and ovate shaped, with rounded or cordate bases.
- Leaf undersides are often lighter green or sometimes purple.
- Leaf upper sides often are variegated with silver or white pattern.
- Bright yellow flowers, tubular-campellate (long, bell-shape), with an upper and lower lip.
- The flowers are produced as pairs of dense clusters internodally (between pairs of leaves) on flowering stems between April and June.
- The plant contains ethereal oils in its leaves, giving it a distinctive odor described as unpleasant and yet not revolting.
- Dense mats can spread over other plants including sword fern, Trillium, and False lily-of-the-valley in woodlands of the Pacific Northwest.
- Tolerates a wide range of soil, water, and shade conditions.
- Typically restricted to woodlands, stream banks and hedgerows.
- Grows on a variety of substrates including limestones, clays, sandstones, conglomerates, recent alluvia and deep loamy soils rich in nutrients.
- Can tolerate waterlogged, damp, and dry soil, although it cannot persist in permanently flooded areas.
- Shade tolerant but thrives in wooded areas that are only lightly shaded.
- The plant grows back heavily and can become dominant after coppicing (cutting back to base).
Reproduction and Spread
- Flower and seed production is typically greater during hot, dry summers; whereas stoloniferous reproduction is more prevalent during wet, cool ones.
- Average seed production by a single plant is approximately 800 seeds.
- Vegetation propagation occurs through stoloniferous plant production as well as through plant fragmentation. When a stem breaks or a portion decays, the resulting fragments grow as individual plants with adventitious root development occurring between leaf nodes.
- The sources of many of the escaped populations occurring in natural areas in the county appear to be compost piles and improperly discarded yard waste.
- Viny plants are easily pulled out by hand during the fall through early spring; however, great care must be taken to remove all parts of plant, as rooted fragments will regenerate.
- Best time to apply herbicide, at least in British Columbia, is between summer and fall, when temperatures are higher than 54 degrees Fahrenheit
- Apply to actively growing foliage
- Herbicides include