2017-09-08 / Home & Garden

Ditch Dweller: Peruvian Primrose–Willow

Stopping to smell the flowers
By Arlene Marturano

In addition to vacant lots, railroad tracks, abandoned home sites, and old cemeteries, roadside ditches introduce the Columbia community to a copious collection of native and non-native plant species. City botanizing may be as close as the stormwater drainage ditch in your subdivision or the channel running parallel to the roadway traveled to and from work.

One of the current conspicuous ditch dwellers of late summer is Peruvian primrose willow, Ludwigia peruviana in the evening primrose family. The South American native was introduced to many countries as an ornamental. The tropical rapidly became naturalized in the southeastern U.S. The 6-12’ tall herbaceous plant forms large thickets along roadsides or lakeshores and generates pollinator traffic jams at blossoms.

Sunshine bright 2.5” wide four-petaled yellow flowers are born singly at leaf axils from July to October. Plant stems and underside of the long lanceolate leaves have short soft hairs.


Native L. alternifolia is as pollinator friendly as its non-native cousin. Native L. alternifolia is as pollinator friendly as its non-native cousin. Prominent pointed green sepals turn reddish when fruit begins to mature. The reddish to brownish seed capsules contain 1,000 to 3,000 tiny light brown round seeds, reassuring its continued success. Seeds are dispersed by water and birds but also wind, mowing machinery, and in mud.

Peruvian primrose has become an invasive weed in many swampy locations such as Florida where it has clogged waterways. The Florida Exotic Pest Council lists the plant as a Category 1 exotic pest.

In Australia, the plant is considered a noxious weed clogging waterways and competing with native water or creek bank vegetation. Residents in Australia are asked to bag seed heads and incinerate to avoid further spread.

Meeting an attractive non-native ditch dweller can lead one to seek native relatives.


Seed capsule of Ludwigia alternifolia Seed capsule of Ludwigia alternifolia A showy native alternative to Ludwigia peruviana is Ludwigia alternifolia aka seedbox.

The common name seedbox refers to the mature boxlike seed capsule, which rattles when shaken. Ludwigia alternifolia prefers a habitat with a moderate amount of water and grows along the edges of marshes and swamps in sandy soils. It prefers an acidic pH of 4-6.

Ludwigia alternifolia has the same ornamental charisma as its non-native cousin but on a smaller scale. It grows to a height of 3’ with small bright yellow ¾” wide flowers from June to August. The perennial is recommended for rain gardens. Seed is available from Everwilde Farms.

Ditch dwellers contribute to erosion control, water quality, aesthetics, and habitat for small wildlife including pollinators and rare plants. Take time to stop and meet the flowers in a ditch near you.



Peruvian Primrose-Willow Flower Peruvian Primrose-Willow Flower

Prominent pointed distinctive sepals of the Peruvian Primrose Prominent pointed distinctive sepals of the Peruvian Primrose

The Peruvian Primrose-Willow has formed a large thicket along Sumter Highway fronting Aldi’s. The Peruvian Primrose-Willow has formed a large thicket along Sumter Highway fronting Aldi’s.

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