A heads up for monitors of streams, vernal pools and other waters:
I took a walk along the headwaters of Rock Brook in the Sourlands a couple weeks ago and noticed the invasive plant white water cress (Rorippa nasturium-aquaticum) in the streambed.
I also found white water cress in a vernal pool about 1500′ north of the stream and at one other vernal pool in the Sourlands several miles away.
Small populations of this plant are easy to remove by gently hand pulling. The roots are often lodged in soft soils. Chilled and immobile hands, damp sneakers, and “stewardship back” (aching lower back from hunching over invasive species) were the worst I experienced.
ABOUT THIS INVASIVE SPECIES:
White water cress is a member of the Mustard family. It can grow fully or partially submersed in shallow waters. It will destroy vernal pools by creating a mass of plant material. It also infests streams, ponds, and other quiet waters where it outcompetes native plants.
It overwinters as bright green basal rosette with pinnately lobed leaves. It is noticably bright green compared to native species that grow similar habitats. For example, our native golden saxifrage (Chrysosplenium americanum) is a dull green.
White water cress flowers are small, white and have 4 petals. Seeds are borne in slender pods. When crushed the leaves smell pungent, like nasturtiums.
Plants can spread via seed or dislodging of the adult plant which can reroot downstream.
White water cress has native and non-native lookalikes, but the pungent smell (and taste this species is cultivated as an edible) is distinctive.
For more information: http://fohvos.org/pdfs/factsheets/Rorippa%20nasturtium-aquaticum_Invasive%20Plants%20Fact%20Sheet.pdf
http://nbii-nin.ciesin.columbia.edu/ipane/icat/browse.do?specieId=91