This family contains some of the most invasive plants in the world. In Hawaii, Koster's Curse, and Miconia sp. are invading native forests and overshadowing other plants. There are nearly 200 genera in this family and 4000 species.
Systematics: Recognized by their clawlike filaments with anthers that dehiss terminally. The leaves have prominent veins that unite again at the top.
Miconia video taken in Hawaii
Miconia is a tree averaging 12-15 m tall with large opposite strongly trinerved leaves (up to over 1 m in length). The leaves are entire, dark green above and purple below. The inflorescence is a large panicle with showy sweet-scented white to pinkish flowers. The fruit is a berry containing as many as 100 tiny seeds.
Miconia can flower two-to-three times per year resulting in prolific seed production. All stages of flowering as well as mature and immature fruits can be observed on a single tree (flowers, mature and immature fruits). The fruits are eaten by and the seeds are dispersed by frugivorous birds. The soil beneath the trees can contain large seed banks. These seeds lie dormant under dense shade but are stimulated to germinate by openings in the canopy.
A mature tree casts dense shade that eliminates the ground cover. Its shallow root system does not hold the exposed soil, resulting in severe erosion. Miconia can spread to all moist habitats, including farms, pastures, roadsides, and forests. A single plant can produce millions of seeds that are widely dispersed by birds or people who inadvertently carry the tiny seeds to new areas on their vehicles or muddy boots.
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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 berry.
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.
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