Common Name: Bigleaf periwinkle Scientific Name: Vinca major L. Symbol: VIMA Group: Dicot Family: Apocynaceae Growth Habit: Vine Subshrub Duration: Perennial

What does it look like?

This low-growing ornamental perennial can cover large areas. Dark green, non-flowering stems grow close to the ground. It roots at the nodes and stretches outward about three feet. The flowering stems grow upward to knee-high, with solitary purplish-blue flowers with five equal petals. Periwinkle leaves are shiny and grow opposite of each other (Bossard et al. 2000).

In California, this plant reproduces by vegetation not seed, for when produced, seeds rarely mature. It spreads by stems that sprawl and form shallow roots at the nodes, creating a carpet-like effect. The flowers bloom from March to July.

Where does it grow?

Periwinkle grows throughout the southern United States and throughout California. This plant does not grow well in direct sunlight, or in dry soil. It prefers moist, shaded areas where growth accelerates in wet periods, but it dies back during frost and resprouts during more optimal conditions. Periwinkle has escaped from gardens and homes where it served as groundcover. It now grows along tree-covered drainages and creeks in coastal areas (Bossard et al. 2000).

Is it in our watershed?

Periwinkle is not a widespread problem in the Mattole but is known to exist near Petrolia, along Chambers Road and behind the Mattole Valley Community Center. There is also an infestation near the junction of Briceland/Thorn heading towards Thorn Junction. Periwinkle has also been observed growing in various gardens and yards of Mattole residents.

Why is it a problem?

Periwinkle alters natural ecosystem processes, especially in sensitive riparian zones. Once established, it forms a dense vegetative cover that inhibits the growth of native species, which lowers species diversity and disrupts native plant communities (Bossard et al. 2000).

How do you get rid of it?

Manual Control: On smaller infestations, cover the growth with black plastic for one or two seasons (BLM 2003). You can pull it up by hand, making sure to remove all roots and nodes. Hand removal is labor-intensive but can be extremely effective if done persistently. The best approach is to work inward from the edge of a patch and pull the weed back on itself to prevent growth during removal sessions. If hand removal is repeated several times during a growing season, it gives native plants a chance to re-inhabit the area, reducing the chances of infestation from invasive species that commonly pop up with any type of ground disturbances (Bossard et al. 2000).

Mechanical Control: Periwinkle is notorious for its ability to resprout quickly from cuttings; mowing or cutting is not recommended as a control method.

Biological Control: At this time, there are no biocontrol agents for periwinkle.

Author:
Unity Peterson, Invasive Plant Program Coordinator, Mattole Restoration Council, Petrolia, CA.

Photograph:
Unity Peterson, 2004

References:
BLM 2003. Noxious Weeds of the Arcata Field Office. Bureau of Land Management. http://www.ca.blm.gov//arcata/arcweeds.html

Bossard, CC., J.M. Randall and M. Hoshovsky. (eds.) 2000. Invasive Plants of California’s Wildlands. University of California Press, Berkeley, CA. Online version: http://groups.ucanr.org/ceppc/Invasive_Plants_of_California's_Wildlands/