Reed Canarygrass
Phalaris arundinacea
Reed canarygrass is a very tall grass with wide leaf blades that are nearly perpendicular to the stalk, long flower/seed heads, and is often a brighter green than our native grasses. A variegated cultivar called ribbongrass is often sold as a landscaping plant (white and green striped blades).

Reed canarygrass is a threat to salmon, as it alters water flow and can take over salmon spawning habitat when it invades stream and river banks. Left unchecked, it forms dense monoculture infestations, preventing other native plants from growing. Invasive wetlands species also alter the composition of insects and other invertebrates near our waterways, which can negatively impact the salmon who eat invertebrates (particularly in their early stages of development).

European Chokecherry
‍Prunus padus
This species is known from one location in Kodiak, but may be present at other locations. This species is difficult to distinguish from Prunus virginiana, which is also invasive and present in Kodiak's developed areas. Unlike most P. virginiana in Kodiak, Prunus padus leaves do not turn red or purple after maturity. Calyxes are longer than they are wide, unlike P. virginiana.

When chopped down or under stress, this tree sends out "sucker" plants and can be difficult to remove once established. This species has is toxic to ruminants such as deer, cattle, sheep, and goats, and has been responsible for poisoning moose calves in Anchorage. Birds eat the berries and can spread them to natural areas, where they can form dense canopy cover and shade out native plants.

The Alaska Division of Agriculture said it issued a quarantine on P. padus and P. virginiana banning the import, transport and sale of these species.

Please contact KSWCD if you have invasive Prunus padus for guidance on eradication.

White Sweetclover
Melilotus alba (=Melilotus albus)
Over ten years ago, a single plant was found and removed from the Kodiak road system. A new infestation was found near the Port Lions ferry dock in 2024. All plants were pulled and the site will be monitored regularly to prevent further spread.

This species is abundant in some parts of the mainland, and each plant can produce thousands of seeds per year. Another very similar plant, yellow sweetclover, is also highly invasive in Alaska. There are no close lookalikes of native Kodiak plants to sweetclover.

Meadow Hawkweed
Hieracium caespitosum (=Pilosella caespitosa)
There is only one known location of Meadow Hawkweed on Kodiak (in a residential area). Can sometimes be confused with the native Woolly Hawkweed, Hieracium triste (=Pilosells tristis), which is usually found in alpine and subalpine habitats. The native hawkweed has very woolly buds that are usually gray to black.

Orange Hawkweed
Hieracium aurantiacum (=Pilosella aurantiaca)
The most widespread of Kodiak's highly invasive species, orange hawkweed spreads by seed and also by rhizomes and stolons (runners). It is reportedly allelopathic, producing phytotoxic chemicals in its pollen grains that inhibit seed germination, seedling emergence, or regeneration of other plants. It forms dense monoculture patches when left unmitigated. It appears to offer little to no food value to bears, unlike the biodiverse native ecosystems it invades. While generalist pollinators may visit blooming hawkweed, it does not support the larvae of many native insects such as butterflies and moths that require specific larval food plants and cannot eat hawkweed.

Please report orange hawkweed seen on trails, mountains, and other natural areas. We do not control orange hawkweed in residential areas or on the bike path.

Himalayan Blackberry/Armenian Blackberry
Rubus discolor (=Rubus armeniacus)
Only one location of Himalayan Blackberry has been found on the archipelago to date, and it has since been eradicated. It is a widespread invasive in the Pacific Northwest, forming dense thickets and displacing native species. This species has very thick, thorny stems, with leaves that consist of 5 stalked leaflets.  

Creeping/Canada Thistle
Cirsium arvense
Creeping Thistle is an invasive species that was likely introduced multiple times as a contaminant of feed, potted plants, and other agricultural products. It is now on the state prohibited and noxious weeds list.

Creeping thistle has smooth, glossy leaves unlike than bull thistle (with hairy leaves), which is also found in Kodiak. Both species have spines on the leaves and stems. There are no native thistles to Kodiak, and both of these purple-flowering thistles are considered highly invasive in Alaska.  

Siberian peashrub
Caragana arborescens
There are few confirmed peashrub plants growing on the Kodiak Archipelago. While they are considered highly invasive, they may be more manageable in our wet climate than in the drier parts of the state where they are more aggressively spreading.

However, we do recommend removing these plants and replacing with non-invasive species as some sites and microclimates in Kodiak may be more hospitable to this species.  

Chokecherry
‍Prunus virginiana
Often planted as an ornamental, the leaves of this tree can be green, reddish, or purple. In Kodiak, most turn red or purple. Calyxes are as wide as they are long (green triangular structures extending between the petals as shown in the 1st photo). When chopped down or under stress, this tree sends out "sucker" plants and can be difficult to remove once established.

The Alaska Division of Agriculture said it issued a quarantine on P. padus and P. virginiana banning the import, transport and sale of these species. ‍

English/Common Ivy
Hedera helix
‍Only known to be growing around homes in a few locations around Kodiak, and currently not known to have escaped into any natural areas here. This species is known to cause exterior damage to buildings and can be found covering trees and forest floors, shading out native species in places where it has escaped into the wild in similar climates.

Creeping Buttercup
Ranunculus repens
Common in the vicinity of the city of Kodiak and Bells Flats, this species seems to be especially well-suited for Kodiak's climate and ecosystem. It is toxic to grazing animals. It completely carpets areas where it is allowed to thrive. Smaller patches can be controlled with covering and/or herbicide, but it is very difficult to eradicate larger infestations.  

Yellow Toadflax/Butter & Eggs
Linaria vulgaris
Currently, we have relatively few infestations of this plant around Kodiak and one large infestation in Old Harbor. Some gardeners may have these in their garden without knowing how invasive it can be. There are very few effective methods to eradicate this plant, and it can aggressively spread on its own. Digging up each plant by the roots seems to have the greatest effect in our control efforts.  

Resembling a snapdragon (Antirrhinum spp.), it can easily be mistaken for that common garden plant. Unlike snapdragons, toadflax flowers have a spur on the back/base of each flower and also has thinner leaves.

English Holly
‍Ilex aquifolium
Only two locations known in Kodiak. It is an invasive species throughout the Pacific Northwest and Alaska, invading woodlands and natural areas. If more were planted, the flowers could get pollinated and allow the fruits to form and then be spread by birds.

Paleyellow Iris
Iris pseudacorus
This species has the potential to form extensive, monotypic stands that increase the density of vegetation and reduce populations of native species in waterways and along shores. It appears to "behave" better in drier areas, but once it enters a wetland it can aggressively spread.

European Mountain Ash
‍Sorbus aucuparia
This species was reviewed by the Alaska Center for Conservation Science and given a new invasiveness rating of 65 in 2026.
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‍European Mountain Ash is widespread around Kodiak, often planted as an ornamental. Please consider planting a non-invasive tree as an ornamental such as Apple/Crabapple, Ussurian Pear, Red Elderberry, or Serviceberry. KSWCD does not currently have the capacity to manage this species, but we would like to emphasize its invasiveness and strongly discourage planting. Birds and other animals have spread their seeds to natural areas where it has started to establish.

Tansy ragwort
‍Senecio jacobaea
With only a couple known active infestations on the archipelago, KSWCD's goal is complete eradication of this species. Most recently, it has been discovered in the Bells Flats area.

Please report ANY sightings of this species or similar-looking plants to KSWCD. We can help assist you with identification, removal, and proper disposal of these plants. Please do not move any parts of this plant without asking about proper disposal methods. Mowing is not effective, as it just encourages the plants to flower at a lower height. A single plant can produce thousands to tens of thousands of seeds, and any nearby soil should be considered contaminated with its seeds as well. Tansy ragwort is toxic, sickening and even killing livestock. Bees that utilize tansy ragwort can product toxic honey. It is reportedly phytotoxic and therefore should be handled with gloves.

Bull Thistle
‍Cirsium vulgare
This species has mostly been documented along roadsides and highly disturbed areas, but it has been found escaping into natural areas on the Kodiak Archipelago. Not only are the prickles a nuisance, its seeds can persist in the soil for a long time, possibly 20 years or more. They are two-year plants, producing flower heads in their second year of growth and then they die after seeding.  They can be grubbed up by the roots or second year plants can be cut down to the base to prevent seed spread.

Oxeye Daisy
Leucanthemum vulgare
Commonly planted in gardens and cemeteries, this beautiful flower is hiding an aggressive nature. We have found it completely taking over native wildflower meadows and natural areas, greatly reducing the biodiversity of the ecosystems it invades.

Common Tansy
Tanacetum vulgare
Tansy has been planted by gardeners. While it is appreciated for its cute flowers and ethnobotanical uses, it is known to take over large areas when unmanaged. Old Harbor has an extensive tansy infestation, demonstrating its ability to thrive in our climate.

Tall Buttercup
Ranunculus acris
Common in disturbed areas, tall buttercup is an aggressive seeder. They can spread into natural areas and form monocultures in the right conditions.

Narrowleaf Hawksbeard  / Crepis
Crepis tectorum
This may look similar to fall dandelion/ hawkbit  (Leontodon autumnalis), but unlike fall dandelion, this species is only known from a couple location on Kodiak. The bracts surrounding the buds and base of the flowers help distinguish this from fall dandelion. The buds and flower bases are also less woolly than fall dandelion, and Crepis tectorum tends to have much taller, slenderer stalks.

Bird's Foot Trefoil
‍Lotus uliginosus
The three records of Lotus uliginosus on Kodiak are the first records for the state for this species. It's highly invasive relative, Lotus corniculatus (AKEPIC rank 65), is sold in local "wildflower" seed mixes and may also become established.

False Spiraea/Sorbaria
‍Sorbaria sorbifolia
False spiraea has been planted as a garden plant in Kodiak and is known to make extremely dense clumps. It is very difficult to remove once established. It is a woody shrub with compound, alternate leaves and a spray of white flowers that emerge at the end of branches.

It might be mistaken for our native goat's beard, Aruncus dioicus. Goatsbeard has much smaller flowers, with flower clusters appearing more like small white fingers drooping from the ends of the branches. It may also be mistaken for mountain ash (Sorbus species), but False Spiraea does not produce red or orange berries in the fall, and is a multi-stemmed bush. Mountain ashes typically have one main trunk and grow to much greater heights.

Please report false spiraea if found growing outside of gardens and landscaped areas. It has recently been assessed for invasiveness; ranking forthcoming.

Dwarf Knotweed
Reynoutria compacta (=Reynoutria japonica compacta)
There are only three known sites with dwarf knotweed on the Kodiak Archipelago. This plant is shorter than Bohemian, Japanese, and giant knotweed and has thinner stems. The flower clusters are pinkish rather than white to cream. Where it has been seen growing, it forms dense cover and may have similar negative impacts to the environment as its highly invasive relatives.

Please do not plant this species in Kodiak!  If you do have this plant, please do not spread any stem or root fragments, as this will help spread it to new locations!