Campuloclinium macrocephalum (Less.) DC.

Nomenclature and Taxonomic Placement

Campuloclinium macrocephalum (Less.) DC., also known by the synonym Eupatorium macrocephalum Less. and common name pompom weed, is a cosmopolitan perennial plant in the Asteraceae family.

Invasive Status

It is considered an invasive weed in some countries.

Native and Introduced Range

This species is native to the southern United States, Central America, and South America, and it has been introduced to South Africa.

Weed Classification in Brazil

It is classified as a principal weed in Brazil.

Introduction History in South Africa

In South Africa, it was originally cultivated as an ornamental plant.

Habitat and Invasion Impact in South Africa

It is often found growing along roadsides, and it has been a concerning invader of undisturbed climax grassland and wetlands there since the 1960s.

Genus Affiliation

It is closely related to Siam weed, and is one of around 268 species in its genus.

Growth Form and Stem Characteristics

Campuloclinium macrocephalum is rhizomatous, with erect stems that can reach 1.3 meters tall.

Stem and Leaf Pubescence

Its stems and leaves are covered in rough, bristly hairs.

Competitive Growth Traits

It forms dense ground-level leaf rosettes that suppress the germination and growth of other plant species, while also producing allelochemicals that negatively impact the growth of neighboring plants.

Winter Survival Adaptation

Each year, the above-ground portions of the plant die back to its root crown, allowing it to survive winter veldfires.

Leaf Morphology

Its leaves are light green, lanceolate-elliptic in shape, and measure 8 cm by 2 cm.

Leaf Margin Characteristics

Leaf margins are serrate, with teeth that become smaller farther from the stem.

Flower Head Bracts

Flower heads are surrounded by 8 mm-long lanceolate, purplish bracts.

Flower Morphology

The flowers are large, pink, and showy, extending 6–8 mm beyond the surrounding bracts.

Fruit and Pappus Characteristics

Mature achenes are black, 5 mm long, and bear a pappus made of simple bristles.

Adaina Moth Biocontrol Research

Moths in the genus Adaina, particularly Adaina microdactyla (Hübner), have been studied as potential biological control agents for this invasive weed.

Adaina Moth Feeding Habits

Genus Adaina moths include flower borers, leaf feeders, and species that form stem galls that provide food and shelter for moth larvae and pupae.

Rust Fungus Biocontrol Discovery

Research conducted at Cedara College of Agriculture identified the rust fungus Puccinia eupatorii, which invades the plant's seeds and kills the entire individual, including its roots.

Rust Fungus Host Specificity

This rust fungus is specific to Campuloclinium macrocephalum, making it an ideal candidate for biological control.

Other Insect Biocontrol Candidates

Other potential insect control agents include a stem-galling thrips of the genus Liothrips, and the moth species Cochylis campuloclinium.

Phytochemical Composition

Chemical analysis of material from this species has identified six triterpenes, one diterpene glycoside ester, six steroids, a flavonoid called cirsilol, and six cinnamic acid derivatives.

Basionym Publication History

The name Eupatorium macrocephalum was first published in January 1830 by Christian Friedrich Lessing in Linnaea 5(1): 136–137.

Genus Name Etymology

The genus name Eupatorium was first used by Linnaeus to honor Eupator Dionysius, also known as Mithridates, an ancient ruler of Anatolia.

Specific Epithet Etymology

The specific epithet macrocephalum means 'large-headed', and refers to the species' inflorescence.