Cattail (Typha australis)
Cattails and Phragmites are plants that can grow both in water and on land. They have tenacious root systems, and need a systemic herbicide for effective chemical treatment. Such treatment is more effective after the flower spikes have formed. Mechanical treatment should not neglect the root system if more than temporary control is desired.
Yellow Iris (Iris pseudacorus)
Yellow Iris forms large clonal populations in ponds and along stream banks that displace native species. The rhizomes of this plant are able to survive rather heavy droughts. Both the rhizomes and seeds of this plant can be transported downstream, allowing for further spread of the plant. Caution should be used when hand-pulling this plant, as it can cause skin irritation.
Forget-Me-Not (Myosotis scorpioides)
Forget-me-not is able to form large mono-cultures, especially in situations where it is in or near a stream. It is still commonly planted in gardens, allowing it to escape into natural environments. This Forget-me-not was a popular garden plant, and reproduces by means of seeds. Since these plants are often found in shallow streams, their seeds can be moved by water.
Purple Loosestrife (Lythrum salicaria)
Purple Loosestrife has the ability to completely dominate wetlands, forming a vast, monotypic stands. These stands prevent the establishment of native wetland plants. It can also have an effect on native wildlife that may not be able to use the plants as effectively for food or cover. By forming these dense stands, Purple Loosestrife can clog waterways, causing problems for both commercial and recreational uses of these areas.
Generally appear in water soaked or slow draining areas in turf. They are hard to get rid of because they produce underground nut-lets that produce new sedge plants. In general, sedges are perennial plants that resemble grasses, grow in shallow water or moist soils, and can reach 4 feet in height. Sedges often grow in thick clusters or tussocks.