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Identify An Aquatic Weed

Controlled Species

Click Here for printable version of controlled and uncontrolled weeds by DBW




Water hyacinth
(Eichhornia crassipes)

Floating

Description
  • Free-floating perennial, sometimes rooted in mud
  • Shiny leaves and spongy stalks
  • Lavender to white flowers with a yellow “eye-spot”
  • When non-flowering and intermediate-aged, can be confused with South American spongeplant
  • Native to South America

Growth Period: spring - late fall; flowers June - October

Habitat
  • ponds, sloughs, channels, canals, streams, rivers, lakes

Control Methods Currently Used By DBW:
  • Chemical Control
  • Mechanical Removal
  • Hand Removal

 

Uruguay water primrose
(Ludwigia hexapetala) 
Floating

Description

  • Floating to emergent perennial
  • Leaves and stems creep onto land, float on the water surface, or grow upright; upright stems are slightly hairy
  • Oval-shaped (younger) to willow-like (more mature) leaves
  • Bright, showy yellow flowers
  • Native to South America

Growth Period: spring - late fall; flowers May - December

Habitat: slow-flowing rivers, lake and reservoir margins, and in the shallow waters of canals and floodplains


Control Methods Currently Used By DBW:
  • Chemical Control
  • Mechanical Removal





 







South American spongeplant
(Limnobium laevigatum) 
Floating

Description
  • Floating to rooted perennial
  • Thick, spongy, floating ovate to spatula-shaped leaves;
  • honeycomb-like spongy tissue on lower surfaces
  • Juveniles develop into mature clumps up to 50 cm (~20 in) tall
  • Small white flowers
  • More mature plants can be confused with water hyacinth
  • Native to Central and South America

Growth Period: spring - late fall; flowers June - September

Habitat: ponds, sloughs, channels, canals, streams, lakes

Control Methods Currently Used By DBW:

  • Chemical Control
  • Mechanical Removal
  • Hand Removal
 

Brazilian waterweed
(Egeria densa)
Submersed

Description

  • Completely submersed with roots anchored in the soil
  • 3-6 leaves in a whorled arrangement
  • Middle and upper leaves are between 15-40 mm
  • (~0.50-1.50 in) long and 2-5 mm (~0.10-0.25 in) wide
  • Small white flowers that extend up to 3 cm (~1.25 in) above the water surface
  • Native to South America

Growth Period: spring - late fall; flowers June - October

Habitat: slow-flowing or still water in sloughs, canals, river, ponds, lakes, reservoirs; often in nutrient-rich substrates

Control Methods Currently Used By DBW:

  • Chemical Control










Curlyleaf pondweed
(Potamogeton crispus) 

Submersed

Description

  • Leaves are floating and/or submersed
  • Wavy, stiff, crinkled leaves between 50-76 mm (~2-3 in)
  • Develop turions, or specialized stem buds that survive
  • unfavorable conditions
  • Turions resemble brown pinecones between 7-25 mm (~0.25- 1 in) long
  • Native to Eurasia

Growth Period: early spring - late summer; flowers May - September

Habitat: ponds, lakes, streams, rivers, reservoirs, irrigation ditches, marsh areas

Control Methods Currently Used By DBW:

  • Chemical Control







Eurasian watermilfoil
(Myriophyllum spicatum)

Submersed

Description
  • Perennial with creeping underground stems; typically submersed, sometimes emergent leaves while flowering
  • Finely divided, whorled leaves with more than 12 leaflet pairs
  • Uniform, parallel, acutely-angled leaf segments
  • Stems and growing tips often red-tinged
  • Does not develop turions, or specialized stem buds that survive unfavorable conditions
  • Small, pinkish, whorled emergent flowers
  • Native to Eurasia and northern Africa

Growth Period: spring - fall; flowers June - September; plants can die back in winter or remain green

Habitat: ponds, lakes, rivers, streams, canals, ditches

 

Coontail
(Ceratophyllum demersum)

Submersed

Description

  • Submersed annual to perennial with firm, forked, toothed,
    olive-green to dark green bottlebrush-like leaves
  • Stems up to 2.5 m (~8.2 feet) long
  • Plants lack roots, and are free-floating or anchored by
    specialized buried stems
  • Develop turions consisting of clusters of scale-like leaves at stem tips
  • Small, inconspicuous, water-pollinated flowers
  • Native to California

Growth Period: germinates in spring, slow growth through winter; flowers June - October

Habitat: ponds, slow-flowing streams, ditches

 











Fanwort
(Cabomba caroliniana)

Submersed

Description

  • Submersed, rooted to free-floating perennial, but can have floating leaves while flowering
  • Opposite leaves on short stalks without toothed margins
  • Submersed, finely divided, red to green fan-shaped leaves
  • Floating leaves are 1-3 cm (~0.40-1.25 in) long
  • Small white to pink to purplish flowers extend above the water surface
  • Introduced from the Eastern United States

 

Growth Period: spring - early fall, flowers May - September

Habitat: ponds, slow-flowing streams, ditches

 


Uncontrolled Species







Floating pennywort
(Hydrocotyle ranunculoides)

Description
  • Floating to terrestrial perennial with branched, creeping stems
  • Bare, fleshy, round to kidney-shaped leaves with 3-7 lobes
  • Stalk attaches to the base of the leaf at the margin, unlike other native pennywort species with stalks that attach to the center of the leaf’s underside
  • Shorter flower clusters of 5-10 flowers with greenish- to yellowish-white to purplish petals
  • Native to North America

Growth Period: rapid growth early spring to early summer, slow growth through winter; flowers March - August

Habitat
  • pond and lake margins, marshes, low swamps, slow streams, irrigation and drainage ditches