2009 High Priority Invasive Plants of the Kenai Peninsula

High High Priority Priority Invasive Invasive Plants of Plants of the Kenai the Kenai PeninsulaPeninsula

20092009

We Need You to Monitor!

Agents of Kenai Peninsula CWMA controlling white sweetclover on the Resurrection River.

Weed warriors of the Kenai Peninsula CWMA eliminating common tansy on a street corner in Kenai.

Kenai Peninsula Cooperative Weed Management Area Needs Your Help Monitoring and Controlling Invasive Weeds!

Photo on cover by M. Shepherd, Bugwood

To report an infestation call:

Homer Soil and Water Conservation District (907)235-8177 ext. 5

UAF Cooperative Extension Service in Kenai(907)262-5824

Or visit:

www.alaskainvasives.org

Materials for High Priority Invasive Plants of the Kenai Peninsula were taken directly from:1) Shephard, M., Huette, T., Nielsen, J., and Lindmuth, C. Selected invasive plants of Alaska. Forest Service Alaska Region R10-TP-130B.2) Carlson, M., Heys, J., Shephard, M., and Snyder. J. Invasive Plants of Alaska. Alaska Association of Conservation Districts.3) bugwood.org

Important Information for Reporting • Some species in this guide are rare and others more

common. The rare species have the verbiage “If found report immediately”. These species, if found early, are most likely to be eradicated from the Kenai Peninsula.

• Only report common species when they are in natural habitats or remote areas (e.g. trails, floodplains, state and national parks).

• When you plan to report a weed in this field guide you will need the following information: date sighted, observer name, phone number, weed(s) spotted, location description, and stem count (1-5, 6-50, 51+).

• Additional information: GPS points, plant photos, plant description (e.g. seedlings, flowers, spreading)

• A perennial that grows to five feet tall with erect, ridged branching stems. Leaves have sharp spines, are wavy, oblong, alternate on stem with woolly hairs on underside. Leaves arise directly from the stem without a distinct leaf stalk. Flowers are purple-pink in clusters at the ends of branches.

• Forms colonies via an extensive horizontal and vertical root system; can eventually cover acres. Also spreads by wind-blown seeds. Young plants appear as basal rosettes that bloom in late summer.

• Uncommon in the Kenai Peninsula. Can be found in fields, pastures, forests, along roadsides, ditches, and river banks. Produces allelopathic chemicals that suppress surrounding vegetation.

Canada Thistle (Cirsium arvense) Sunflower Family

If found report immediately! 235-8177 ext. 5

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• Biennial plant that grows up to 3 feet tall from a stout taproot. Basal rosettes have deeply lobed gray-green leaves. Flower heads pink-purple, consisting of ray florets only, solitary at the end of stem branches. Involucral bracts are topped with dark comb-like fringe giving a spotted appearance.

• Spreads only by seed. Adapted to well-drained soils. Responsible for millions of dollars in economic loss and environmental damage in the western United States.

• Not known to occur in Kenai Peninsula; however, found in Anchorage, Valdez, and numerous locations in Southeast Alaska. Look for this plant in natural and unnaturally disturbed areas.

Spotted Knapweed (Centaurea biebersteinii) Sunflower Family

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Bird Vetch (Vicia cracca) Pea Family

M. Rasy, Bugwood

R. Old, Bugwood

• Perennial which reproduces by seed and vegetatively by underground rhizomes. Multiple, branching vine-like stems have small tendrils and alternate, pinnately-compound leaves with 8 to 10 leaflets. Bilaterally symmetrical purple flowers are arranged on a one-sided spike. Flowering occurs from spring to late fall. Seeds contained in inch-long, brown, lance-shaped pods.

• Bird vetch aggressively climbs fencing, trees, bushes, and other vegetation, monopolizing sunlight, space, and moisture.

• Uncommon in the Kenai Peninsula. Look for bird vetch in disturbed areas including roadsides, trails, and hay fields.

Bird Vetch (Vicia cracca) Pea Family

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• Annual herb with thick, many-branched, hexagonally angled stems which can grow to 10 feet. Stems smooth, multi-branched, with large swollen glands at the nodes. Lower leaves opposite, while upper leaves are whorled with three leaves to a node. Leaves lance-shaped, 6 inches long, from a stout petiole. Leaf margins finely, sharply serrated. Irregular flowers one inch in length, pink-purple to white, with five petals.

• Rapidly clogs wetlands and streams. Prolific seed production and aggressive spreader make for difficult control. Unwary gardeners have contributed to its spread into Alaska.

• Rare in Kenai Peninsula. Thrives in lowlands, riparian zones, and along beaches.

Ornamental Jewelweed Balsam Family(Impatiens glandulifera)

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• A perennial plant which grows 2 to 8 feet tall. Produces tall spikes of purple-magenta flowers, each with 5 to 7 “ruffled” petals and a small yellow center. Lance-shaped leaves have smooth edges, and are usually arranged opposite one another, in groups of 2 or 3 along the stem. As many as 40 stems arise from the base of a well-established mature plant. Stems are 4 or 5-sided in cross-section.

• An aggressive wetland invader, purple loosestrife chokes waterways, degrading wildlife habitat and fish spawning areas. Single plants can produce millions of tiny seeds.

• Purple-pink flower spikes may be confused with Alaska’s native fireweed (Epilobium spp.) but in Alaska purple loosestrife blooms in the fall, well after fireweed blooms have faded.

• Not known to occur in the Kenai Peninsula; however, one infestation was found and is currently being managed in Anchorage. Look for purple loosestrife in wetlands.

Purple Loosestrife (Lythrum salicaria) Loosestrife Family

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• Annual which can grow to 4 ft tall. Flowers purple, pink, white, or pale yellow and grow in clusters at base of leaf stalks. Stems branched, bristly-haired, and square in cross section. Leaves opposite on stalks, egg-shaped to lance-shaped with large rounded teeth and pointed tips. Leaves prominently veined and covered with bristly hairs.

• Forms dense stands on disturbed sites, forest edges, riparian areas, meadows, and beaches. Numerous seeds are small and easily spread on shoes, tires, and recreational equipment. Gardeners quickly come to despise this plant.

Splitlip Hempnettle (Galeopsis bifida) Mint Family

Report if found in natural habitat or remote area! 235-8177 ext. 5

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Oxeye Daisy (Leucanthemum vulgare) Sunflower Family

K. Beck & J. Sebastien, Bugwood

Montana Statewide NWAEPA, Bugwood

Montana Statewide NWAEPA, Bugwood

• A short-lived showy perennial that spreads vegetatively by rhizomes or from seeds. Heads solitary at the ends of branches, consisting of ray and disc flowers. Leaves hairless to sparsely hairy, becoming progressively smaller towards the top, spoon-like leaves on base of plant.

• Common in Kenai Peninsula. Grows in roadside ditches, disturbed areas, beach meadows, and landscaped areas.

• Distinguished from Shasta Daisy by oxeye’s smaller flower heads, spoon-like leaves, and large teeth on the leaf margin.

Similar Invasive: Scentless False Mayweed(Tripleurospermum perforata), is a similar looking species that is spreading across the Kenai Peninsula. However, leaves are divided into numerous narrow, thread-like, branched segments. The flowers of this invasive lack odor, which easily distinguishes it from Chamomile.

Oxeye Daisy (Leucanthemum vulgare) Sunflower Family

Scentless False Mayweed7


• An herbaceous perennial that forms extremely dense stands, shading out native vegetation. Stems to 10 feet tall, hollow, bamboo-like with thickened nodes where the leaf stalks meet the stem. Reproduces from extensive spreading rhizomes or broken-off pieces of stem. Leaves broadly oval and up to 6 inches long. Has small white to greenish-white flowers that bloom in late August/September. Dies back, turning bright yellow before dropping leaves in the fall.

• Clogs waterways and lowers quality of habitat for wildlife, fish, and invertebrates. Has displaced salmonberries along shorelines.

• Not known to occur in the Kenai Peninsula but could likely thrive here. Grows in Kodiak and Southeast Alaska. Found on roadsides, stream banks, and beach meadows.

Japanese Knotweed Buckwheat Family(Polygonum cuspidatum, P. bohemica)

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• A biennial legume. In the first season of growth, sweetclover produces vegetative shoots which may reach 12 inches. In its second season of growth, plants can grow up to 6 feet. Upright growth habit. Intolerant of shade. White and yellow sweetclover are very similar, differing primarily in flower color. Leaves toothed and compound with three leaflets.

• Growing aggressively along the Matanuska, Nenana, and Stikine Rivers of Alaska. Sweetclover has been shown to negatively impact native vegetation in river habitats.

• Excluding Seward, uncommon in the Kenai Peninsula. Rapidly colonizes open waste areas and quickly spreads along riparian areas and riverbanks.

White Sweetclover (Melilotus alba) Pea Family Yellow Sweetclover (M. officinalis)

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• Both native and non-native species of yellow-flowering hawkweed exist in Alaska. Native Alaskan hawkweeds lack stolons, have branched stems with many leaves, and generally are found in high-elevation meadows.

• Mouse-ear hawkweed has a solitary yellow flower• Similar in appearance to orange hawkweed, meadow hawkweed

grows to 3 feet, its stem covered in coarse black gland-tipped hairs, and bearing multiple yellow flowers.

• Narrowleaf hawkweed has hairy leaves with serrated margin.• Common hawkweed has 7-10 stem leaves that are strongly toothed

and taper to a narrow stem.• Uncommon in Kenai Peninsula but are found in Swanson oil field and

Kenai area. Look for these species among natural and unnatural disturbances including roads and river floodplains.

Non-native Yellow Flowered Hawkweeds Sunflower FamilyMeadow Hawkweed (Hieracium caespitosum) Mouse-ear hawkweed (H. pilosella) Narrowleaf Hawkweed (H. umbellatum) Common Hawkweed (H. lachenalii) hawkweed

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• Annual or winter annual to 3 feet tall. Basal leaves are stalked and lance-shaped with margins varying from numerous backward-pointing teeth to deeply lobed. Stem leaves clasp the stem. Bracts below dandelion-like yellow ray flowers are smooth, lacking hairs. Milky juice produced by stems when broken.

• Competes with seedlings, forage plants, cereals and oilseeds. Spreads into riparian areas and burned lands.

• Common in the Kenai Peninsula. Often found on disturbed soil, waste places, river floodplains, or roadsides. Thrives in dry, coarse soils.

Narrowleaf Hawksbeard (Crepis tectorum) Sunflower Family

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Fall Dandelion (Leontodon autumnalis) Sunflower Family

T. Heutte, Bugwoodbotanika.bf.jcu.cz

• Fall dandelion is a perennial plant that spreads from both rhizomes and seed. Leaves are clustered at the base of the plant and are deeply lobed. Thin stems arise directly from the basal rosette, which can have one to many yellow flower-heads. Plant stems have few leaves and do not exude a milky sap when broken.

• Fall dandelion does not bloom until late in the growing season. This species is displacing grass species in pastures and rangeland on the Kenai Peninsula. It is likely being transported by humans with contaminated hay.

• Fall dandelion is common along roads and hayfields in and around Homer and Anchor Point.

Fall Dandelion (Leontodon autumnalis) Sunflower Family

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• Perennial with flowers and leaves similar to common dandelion. Plants grow 4 to 5 feet tall. Flower heads are 1 to 2 inches across. Stems are branched only at the top. Basal and stem leaves have prickly margins. Plants exude a milky sap when broken.

• Can drastically reduce crop yields in agricultural areas and displace native plants on beaches and in meadows by competing for light and nutrients.

• Rare in Kenai Peninsula. Can grow in waste areas, gardens, meadows, woods, lawns, roadsides, beaches, ditches, and river and lake shores

Perennial Sowthistle (Sonchus arvensis) Sunflower Family

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• Perennial, spreads by seed and by short rhizomes, forming dense clumps. Flat-topped cluster of button-like yellow flowers lacking petals. Numerous composite flower heads (20 to 200 per plant). Leaves alternate and deeply divided into narrow individual leaflets, giving a feathery appearance. Plants grow to five feet tall. Strong odor.

• Mildly toxic to grazing animals. Used commonly in gardens where it tends to spread into other yards and natural areas. This plant can restrict the flow of water along streams.

• Excluding flower gardens, tansy is uncommon in the Kenai Peninsula. Grows along roadsides, river and stream banks, and beach meadows.

Common Tansy (Tanacetum vulgare) Sunflower Family

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• Short-lived perennial with one to several stems arising from a taproot. The plant grows 1 to 4 feet tall. Leaves deeply cut. Basal leaves stalked 2 to 8 inches long. Leaves become smaller and petioles become shorter moving up the stem. Flower heads borne in terminal clusters, heads consist of yellow ray and orange disc florets. Ray florets or “petals” number 10 to 13.

• Contains a toxic compound responsible for considerable livestock mortality. It is estimated that the state of Oregon has lost $7 million per year to livestock poisoning by this plant.

• Not known to occur in the Kenai Peninsula. Found in waste places, roadsides, clear-cuts, and meadows.

Tansy Ragwort (Senecio jacobaea) Sunflower Family

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Creeping Buttercup (Ranunculus repens) Crowfoot Family

R. Old, Bugwood


• Creeping buttercup is a perennial plant with stems that grow up to 3 feet long. Basal leaves are up to 4 inches wide, trifoliate with toothed margins. Flowering stems are long and erect. Generally has several flowers that are showy with 5 yellow petals. Spherical seedheads have about 12 flattened and rounded fruits.

• Thrives in wet soils. Often found in ditches and wetlands. Takes over yards and waste places.

• Creeping buttercup is all over Kodiak and small populations have been reported in the Kenai Peninsula.


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• Perennial shrub to 10 feet tall from a forked taproot. Stems strongly angled and leaves clover-like. Flowers numerous, bright yellow, arising from the leaf bases along the stem, similar in appearance to garden peas. Fruits pea like, flattened, brownish-black. Reproduces vegetatively and from seeds. Seeds remain viable for up to 80 years.

• Grows into dense impenetrable stands which prevent reforestation, create fire hazard, and eliminate forage for herbivores.

• Rare in the Kenai Peninsula. Can grow along road sides, forest edges, clearings, and meadows.

Scothbroom (Cytisus scoparius) Pea Family

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• Similar to snapdragons. An aggressive perennial that can reproduce by seeds or rhizomes, with 1 to 25 stems per plant. Woody, smooth, erect, leafy, often in clumps to 2 feet tall. Numerous pale green leaves to 3 inches long, alternate, narrow and pointed at both ends. Flowers borne at the end of each stem in spike-like clusters, yellow, with central bearded orange patch, one inch long, with a spur extending below the lower lip of the corolla.

• A persistent, aggressive invader, capable of forming dense colonies. Toxic to grazing animals.

• Common in Kenai Peninsula. Grows in natural and unnatural habitats such as roadsides, waste areas, lake shores, beach meadows, pastures, and edges of forests.

Common Toadflax, Butter & Eggs Figwort Family(Linaria vulgaris)

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M. Shephard, Bugwood

M. Shephard, Bugwood

• A perennial with colorful orange-red flowers about one inch in diameter. Flowers consist of ray florets only with notches upper margins. Leaves clusters in a basal rosette. Leaves are covered in soft white hairs; stems have shorter dark hairs. Stems 2 to 12 inches, occasionally growing to 2 feet.

• Spreads by stolons, rhizomes, and seed. A favorite flower of unwary gardeners and wildflower enthusiasts. Moves into forb meadows and wetlands where it spreads more aggressively. Forms dense mats, crowding out native plants.

• Common in Kenai Peninsula. Found along roads, yards, riparian areas, and beaches.

Orange Hawkweed (Hieracium aurantiacum) Sunflower Family

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Eurasian Watermilfoil (Myriophullum spicatum) Watermilfoil Family

A. Fox, Bugwood O. Risteski

• Eurasian watermilfoil is a submersed aquatic plant, with stems 3 feet long or more. Leaves are whorled, highly dissected, and composed of 28-48 thread-like divisions. Spikes emerge above the water, and flowers are borne in the axis of bracts. Plant forms dense mats that grow over the surface of water.

• Found in fresh to salty water of ponds, lakes, slow-mowing streams, reservoirs, estuaries, and canals.

• Not known to occur in Alaska but could readily be spread into Kenai Peninsula by float planes. This invasive alters ecosystems and makes poor habitat for waterfowl, fish, and other wildlife. Look for this invasive in wetlands.

Eurasian Watermilfoil (Myriophullum spicatum) Watermilfoil Family

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Reed Canarygrass (Phalaris arundinacea) Grass Family

J. Randall, Bugwood

B. Rice, Bugwood

• Tall reed-like perennial rising from stout rhizomes. Stems are hollow, 2 to 6 feet tall, with bluish-green waxy coating. Leaf blades flat, up to 3/4 inch wide, with transparent ligules. Panicle inflorescence is 6 to 18 cm long with spikelets occurring in clusters on short scabrous branches. Seed heads compact at first then opening at maturity.

• Forms dense, persistent, mono-specific stands that may threaten salmon habitat. Difficult to impossible to eradicate once established. Spreads within sties by creeping rhizomes, effectively excluding all other vegetation.

• Common in the Kenai Peninsula. Spreading along several Kenai Peninsula waterways including the Kenai River. Look for reed canary grass in human disturances and wetlands.

Reed Canarygrass (Phalaris arundinacea) Grass Family

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If found in wetlands report immediately! 235-8177 ext. 5

Smooth Cordgrass (Spartina alterniflora) Grass Family

L. Lee, USC HerbariumUSDA NRCS PLANTS Database, Bugwood

• Smooth cordgrass grows 2-4 feet tall. Leaf blades are 8-24 inches long, tough, greenish-gray in color, and ¼ inch wide becoming folded at tip. Plants are deciduous, and stems die back at the end of each growing season. Flowering part of plant is 16 inches long with 5-20 spike-like braches up to 5 inches long each.

• Found in the intertidal zone between mean high water and mean low water.

• Not known to occur in Alaska. Still, plants may be migrating on oceanic currents northward from British Columbia. Forms extensive stands that convert mudflats and channels into marsh. Conversion results in severe impacts to waterfowl and shellfish populations.

Smooth Cordgrass (Spartina alterniflora) Grass Family

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Documents

2009 High Priority Invasive Plants of the Kenai Peninsula