Invasive Plant Species

Katmai National Park and Preserve is one of the most pristine parks in Alaska, but invasive plants pose a serious threat to the diverse ecosystems in the park. Invasive plants are characterized as plants that are introduced by humans, intentionally or unintentionally, to areas where they have not existed before and have the ability to establish and outcompete native species. Katmai has relatively few invasive plants in the park and the Exotic Plant Management Team aims to control the spread and minimize the negative impacts that invasive species can have on native plant communities. As a visitor, you can do your part to prevent the spread of invasive plants by thoroughly cleaning your gear and boots in between uses.

Common Dandelion

NPS Photo/Santa Monica Mountains National Recreation Area

Common Dandelion (Taraxacum officinale ssp. officinale)
Although Katmai has multiple species of native dandelions, the common dandelion is a threatening invasive in the park. Common dandelions, native to Europe and Asia, produce many wind dispersed seeds that easily spread over large areas. These resilient plants have the ability to reproduce multiple times in a year, so they can be very difficult to get rid of.

Shepherds purse invasive flower.

Shepherd’s Purse (Capsella bursa-pastoris)
This tiny member of the mustard family can quickly establish in a wide arrangement of disturbed areas. Similar to the native lyrate rockcress (Arabidopsis lyrata), shepherd’s purse can be distinguished by its unique heart shaped seed pods and leaves that clasp the stem. Native to Eastern Europe and Asia, this plant is capable of reproducing multiple times in a season and its seeds remain viable in the soil for many years.

common plantain

NPS Photo/Santa Monica Mountains National Recreation Area

Common Plantain (Plantago major)
Native to Europe and Asia, common plantain is a widespread invasive that can be found at Katmai. These plants are low to the ground and produce a spike of tiny green flowers that can yield up to 20,000 seeds per plant. Despite the name, these plants are not related to the plantains that are commonly eaten.

sheep sorrel

NPS Photo/Denali National Park And Preserve

Sheep Sorrel (Rumex acetosella)
This aggressive invasive plant, native to Eurasia and the British Isles, spreads quickly by underground stems known as rhizomes. Often one of the first plants to move into disturbed areas, sheep sorrel is very difficult to control once it becomes established in an area.

Pineapple weed

NPS Photo/Santa Monica Mountains National Recreation Area

Pineapple Weed (Matricaria discoidea)
Pineapple weed is a small fragrant plant that can form dense mats. This invasive plant has grown so widespread that it is no longer targeted for treatment in the high use areas of Katmai.


Mouse-ear Chickweed (Cerastium fontanum)
Mouse-ear chickweed is an invasive plant with tiny white flowers that can be found in disturbed areas. Native to Europe, this plant has the ability to spread horizontally when stems fall. There are many native chickweeds in Katmai as well, so care must be taken when identifying this invasive.


Prostrate Knotweed (Polygonum aviculare)
Prostrate knotweed is a small creeping plant that is native to Eurasia. This invasive plant becomes easily established in gravely, disturbed sites and has seeds that can remain viable for many years in the soil.


Narrowleaf Hawksbeard (Crepis tectorum)
This invasive plant, native to Europe and Asia, is commonly found in fields and on roadsides. Narrowleaf hawksbeard is not found in large numbers within the park, so it is meticulously controlled to prevent spread.


Bird Vetch (Vicia cracca)
Bird vetch is a particularly threatening invasive plant in the pea family. This plant has tendrils that will climb on nearby vegetation and choke it out. This plant has been controlled in Katmai in the past and recent surveys have not found any additional infestations.


There are two invasive species of Elodea, or common waterweed, that have been causing problems in lakes in Alaska in recent years. Although it has not been found within Katmai’s lakes, the high amount of floatplane traffic on lakes in the park makes it at high risk for infestation. Elodea can travel on floatplanes from infested lakes in other parts of Alaska and easily establish in new areas. The Exotic Plant Management Team at Katmai regularly surveys lakes in the park for the presence of this aquatic invasive.

Last updated: October 11, 2016

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