Invasive Species Factsheet: Java Waterdropwort

Java waterdropwort grows in dense colonies like a groundcover and can reach heights of 9-28" tall. It is found in both wild and cultivated settings. This plant needs wet soils and is often found in standing water.

The leaves of java waterdropwort are  pinnately compound  and arranged alternately on the stem. Each leaf is 4-12" long and 3-8" wide. Individual leaflets are 2" long. The leaves of java waterdropwort resemble those of celery, but without the thick petiole (which is the part of celery most often eaten).

Fibrous roots of java waterdropwort are capable of forming at nodes on sections of the stem that come in contact with the ground or are submerged in water. In late summer or early autumn, java waterdropwort produces showy, petite white flowers in umbels at the end of its stalks.

Brittle stems of java waterdropwort are jointed and hollow and can easily break off and take root. Java waterdropwort is a hermaphrodite plant species, meaning it has both male and female organs. It is pollinated by insects and is self-fertile.

Java waterdropwort has been found in several U.S. states spanning as far north as Minnesota, as far south as Georgia, and as far east as New Jersey. According to the U.S. Geological Survey, one population was discovered in  New Hampshire  but has since been eradicated.

In Pennsylvania, java waterdropwort has only been found in Berks and Franklin counties, making it a high priority species in the Commonwealth. Any suspected findings should be reported immediately.

In the wild, java waterdropwort can be found growing in wet areas such as freshwater marshes, swampy fields, lakeshores, and wet meadows. It also grows along ditches, canals, and streams, though prefers slow-moving or stagnant water.

Java waterdropwort may also be found in cultivated settings such as water gardens, rain gardens, and areas that require groundcover. However, it is not advised to include this known invasive plant in your home landscape given its ability to escape into natural settings.

Java waterdropwort spreads vigorously via asexual reproduction by sending out runners that take root in areas with wet soils.

Storm events can promote the spread of this plant by increasing the chances for fragments to float downstream to uninvaded areas. Once in a new location, java waterdropwort can form adventitious roots and begin establishing a new colony.

To help prevent the spread of this and other invasive species, clean your boats, shoes, and other recreational gear and properly dispose of or leave on site any plant fragments you find.

Several other species with flowering umbels, compound leaves, and (in some cases) preferences for wet locations may look similar in appearance to java waterdropwort. They include:

•  Wild parsnip  (Pastinaca sativa)
•  Bishop's weed  (Aegopodium podagraria)
• Plants in the genus  Osmorhiza 
• Plants in the genus  Angelica 

Wild parsnip differs from java waterdropwort due to its yellow colored-flowers. In comparison, java waterdropwort always has white flowers.

Bishop's weed and plants in the genus Osmorhiza are often found in moist locations, but will never be found in standing water, which is java waterdropwort's preferred habitat. Also, the fruits of Osmorhiza species are hairy, which is not true of java waterdropwort.

Finally, species in the genus Angelica have globe-shaped umbels, whereas the umbels of java waterdropwort are flat.

Note: Other potential look-alike species with white-flowering umbels are often found in drier locations, or have more finely divided/serrated leaves as compared to java waterdropwort.

Java waterdropwort can form dense colonies that aggressively spread into wetlands and outcompete native species. Broken plant fragments are able to form adventitious roots, thus increasing its chances for spread.

This plant is ultimately capable of choking or obstructing streams and other waterways once established, causing a decline in ecological integrity and decreased recreational value. Attempts should be made to recognize this species in the wild and remove it where possible.