swamp willowherb

Names and Synonyms

Common Names

• swamp willowherb
• water oleander
• swamp-loosestrife
• water-willow
• Whorled Loosestrife
• water willow
• willow-herb

Scientific Names

Accepted name

Synonyms

• Lythrum verticillatum
• Nesaea verticillata
• Decodon aquaticus
• Decodon verticillatus var. laevigatus
• Decodon verticillatus var. pubescens

Regional and Traditional Names

Sources: Wikidata, Catalogue of Life

Taxonomical Classification

This plant belongs to the kingdom Plantae and is classified within the phylum Streptophyta and the class Equisetopsida. Following the subclass Magnoliidae, it is further categorized under the order Myrtales and the family Lythraceae. Finally, its specific taxonomic identity is defined by the genus Decodon.

Sources: The World Checklist of Vascular Plants (WCVP)

Distribution

This plant, known as Decodon verticillatus, is primarily distributed across several provinces in Eastern Canada. Its range includes the coastal and inland regions of New Brunswick and Nova Scotia. It can also be found throughout the province of Ontario. Additionally, the species is well-established within the territory of Québec. Finally, its presence is documented on the island of Prince Edward Island.

Sources: The World Checklist of Vascular Plants (WCVP)

Botanical Identification

Life history

The life history of Decodon verticillatus is characterized by its nature as a perennial plant, allowing it to persist through multiple growing seasons within its wetland habitats. As a perennial species, it undergoes cyclical stages of vegetative growth and seasonal flowering, often relying on established rhizomatous systems to survive dormant periods. This long-term life cycle enables the plant to maintain a stable presence in aquatic or marshy environments, where it can continuously regenerate and expand its coverage over several years rather than completing its cycle within a single season.

Lifecycle :

perennial

Morphology

The morphology of Decodon verticillatus is characterized by a shrubby growth form, exhibiting a woody structure that allows it to reach an average plant height of approximately 2.4 m. This species functions as a self-supporting plant, requiring neither obligatory nor facultative climbing mechanisms to maintain its posture. It is classified as a semiaquatic organism, typically found in environments that transition between water and land, and it thrives as a terrestrial species rather than an epiphyte. Furthermore, the plant is independent in its nutritional requirements, showing no parasitic tendencies.

Aquatic :

semiaquatic

Climber :

self-supporting

Epiphyte :

terrestrial

Growth form :

shrub

Parasite :

independent

Plant height mean:

2.4 m

Woodiness :

woody

Physiology

The physiology of Decodon verticillatus is characterized by a C3 photosynthetic pathway, which dictates its metabolic processes and carbon fixation mechanisms. Under this C3 pathway, the plant utilizes the enzyme Rubisco to fix atmospheric carbon dioxide directly into a three-carbon compound during the Calvin cycle. This physiological framework typically requires the plant to maintain specific stomatal conductance patterns to balance gas exchange with transpiration, especially in its natural aquatic or semi-aquatic habitats. Because it relies on C3 metabolism rather than C4 or CAM pathways, its carbon assimilation efficiency is highly dependent on environmental factors such as light intensity, temperature, and the availability of moisture in its surrounding ecosystem.

Photosynthetic pathway :

C3

Reproduction

The reproduction of Decodon verticillatus is characterized by a specific flowering window and the production of minute seeds. The flowering period typically commences in July and concludes in August. The resulting seeds are exceptionally small and uniform in their physical properties, exhibiting a consistent seed mass of 0.00073 g, with no variation between the minimum and maximum recorded values. Similarly, the seed volume is highly standardized, maintaining a constant measurement of 0.65 mm³ across the minimum, maximum, and mean values.

Flowering time :

Jul

Flowering time :

Aug

Seed mass mean:

0.00073 g

Seed volume max:

0.65 mm³

Sources: Global Inventory of Floras and Traits (GIFT)

Chemicals

Decodon verticillatus has 1 reported phytochemicals identified across 0 scientific publications and several other databases. The most consistently reported chemicals include decine.

decine

1. Journal of ethnopharmacology