Koster’s curse is a coarse perennial shrub up to 2 m tall. The
stems are covered with red bristles that lighten with age. The leaves
are opposite, simple and petiolate. The ovate-to-oblong leaf blades are
hairy with crenate margins. The surfaces appear pleated. Five major veins
originate at the base of the leaf and extend to the apex. The inflorescence
is a panicle that can be terminal or axillary. The calyx has five hairy
linear lobes atop a long urceolate hypanthium. The corolla consists of
five small white petals. The fruit is a hairy ovoid many seeded bluish-black
The shrub has become common in wet open or disturbed places. In areas
with abundant moisture, it can grow vegetatively and reproduce throughout
the year. Its success as an invasive species is due to prolific seed production,
high seed viability, rapid growth, broad environmental tolerances, and
abundance of dispersal vectors including birds, pigs, and humans.
The shrub spreads rapidly into forest gaps that have been opened due
to disturbance. Once it becomes established Koster’s curse forms
dense monotypic stands that shade out all the understory vegetation.