Ageratum spp. – Ageratum

Ageratum sp. - Ageratum, Whiteweed, Flossflower, Maile Honohono, Maile Hohono, Maile Kula (blue flowers)

Ageratum sp. - Ageratum, Whiteweed, Flossflower, Maile Honohono, Maile Hohono, Maile Kula (white flowers)

Ageratum sp. - Ageratum, Whiteweed, Flossflower, Maile Honohono, Maile Hohono, Maile Kula

Ageratum sp. - Ageratum, Whiteweed, Flossflower, Maile Honohono, Maile Hohono, Maile Kula (leaves)

Plant Name

Scientific Name: Ageratum spp.

Common Names: Ageratum, Whiteweed, Flossflower, Maile Honohono, Maile Hohono, Maile Kula

Plant Characteristics

Duration: Annual, Perennial

Growth Habit: Herb/Forb

Hawaii Native Status: Introduced. These naturalized wildflowers are native to the tropical Americas.

Flower Color: Lavender to purplish blue, White

Height: Up to 32 inches feet (0.8 m) tall or more

Description: The small, fuzzy, rayless flower heads are in dense, almost flat-topped clusters. The leaves are light green, opposite, toothed, sparsely to densely hairy below, and elliptic-oblong, triangular, or egg-shaped. The stems are weak, erect to decumbent, and sparsely to densely hairy.

Two very similar Ageratum species are found here in Hawaii and can be difficult to distinguish. Tropical Whiteweed (Ageratum conyzoides) is a taller plant and has leaves with a gland-dotted lower surface, while Bluemink (Ageratum houstonianum) is lower growing plant and does not have a gland-dotted lower leaf surface. Cultivated varieties of Bluemink are typically much lower-growing and have a mounding form instead of an upright form.

Here in Hawaii, both Ageratum species grow as weeds in disturbed areas and along roadsides at lower to middle elevations.

Both Sticky Snakeroot (Ageratina adenophora) and Spreading Snakeroot (Ageratina riparia) look similar to Ageratum, but these two plants have white flowers and purple stems.

Special Characteristics

Foul-smelling – The foliage has an unpleasant smell.

Poisonous – The plants are poisonous.

Classification

Kingdom: Plantae – Plants
Subkingdom: Tracheobionta – Vascular plants
Superdivision: Spermatophyta – Seed plants
Division: Magnoliophyta – Flowering plants
Class: Magnoliopsida – Dicotyledons
Subclass: Asteridae
Order: Asterales
Family: Asteraceae – Aster family
Genus: Ageratum L. – whiteweed

More About This Plant

Hawaii County Distribution Map