Invasive Aquatic Plants Identifying Known & Potential Weeds in the PNW
Oregon Lake Watch Center for Lakes and Reservoirs
Overview • Impacts – why aquatic weeds matter? • Growth forms – Submerged – Floating-leaf – Emergent (shoreline)
• Aquatic plants, including – Common invasives – New (high priority) invasives – Common native look-alikes
• Importance of confirmation & reporting
Ecological Impacts • • • • •
Reduce light penetration & mixing Reduce species diversity Alter temperature, dissolved oxygen & pH Degrade fish habitat Altered nutrient cycling
Economic Impacts • Reduce flow in irrigation canals and drainage ditches – Increased cost of irrigation – Flooding – Clogged pumps & intake structures
• Loss of recreational resources • Negative impacts on property values
Photo: Bridgetotrade.net
Photo: Enviroscience, Inc
Human Health and Safety
Growth forms
How do aquatic weeds move and spread? Invasive plants and animals have spread to new areas due to: boats and trailers bait buckets water movement
Osceola County, Hydrilla Dem. Proj.
(waves, downstream movement)
waterfowl & other animals
PSU-CLR
Aquatic plants can reproduce & spread by: plant fragments www.brantlakemilfoil.org
seed
tubers
turions
Rich Miller, PSU-CLR
www.birdphotos.com
Submerged Aquatic Plants
Eurasian watermilfoil (Myriophyllum spicatum) a.k.a. “EWM”
EWM Habitats & Growth • • • • • • • • •
Lakes, reservoirs, ponds, rivers, and streams Fresh to brackish water (up to 15 ppt) Depth: (0.5) 1-5 (10) meters pH range: 5.4 to 11 Fine-textured, inorganic sediment Early & rapid spring growth (water temp >15 ͦ C ) Tops out in water < 5 m Autofragmentation in fall/early winter Overwintering root crowns
Other Myriophyllum spp. Whorled watermilfoil (M. verticillatum)
Andean watermilfoil (M. quitense)
J. Parsons, WA DOE A. Hipp, U of WI-Stevens Point
Š2012 Vernon Smith
V. Morgan, PSU-CLR
V. Morgan, PSU-CLR
Northern watermilfoil (M. sibiricum)
Identification of Eurasian milfoil • 4 leaves per whorl • 14 or more leaflet pairs • leaves more squared in outline • collapse more when out of the water • no winter buds
Hybrid watermilfoil (M. spicatum × sibiricum)
michiganlakeinfo.com
Variable-leaf watermilfoil (M. heterophyllum)
V. Morgan, PSU-CLR
L.J. Mehrhoff, U of CT, Bugwood.org
© 2014 Donald Cameron
L.J. Mehrhoff, U of CT, Bugwood.org
Milfoil Character Comparison submerged leaves Status in PNW # leaflet pairs
leaf size
leaves/whorl
emergent leaves (bracts)
winter buds (turions)
Northern watermilfoil (Myriophyllum sibiricum)
NATIVE
<14 (5-14) < 4 cm long
3 to 5
reduced (1-3 mm long); smaller than flowers
yes
whorled watermilfoil (Myriophyllum verticillatum)
NATIVE
<14 (5-14) < 5 cm long
4 to 5
2-10 mm long; deeply pinnately lobed
yes
Andean watermilfoil (Myriophyllum quitense)
NATIVE
2 to 5
0.5-1 cm long; partially toothed
yes
no
Parrot feather (M. aquaticum)
INVASIVE
Eurasian watermilfoil (M. spicatum)
INVASIVE
5-10
1.5 - 4 cm long
10-15
1.5 - 3.5 cm long
3 to 6
2-5 cm long; 16-18 leaflet pairs stiff, waxy, bright green
> 14 (12-24) 2 - 4 cm long
3 to 6
reduced (1-3 mm long); smaller than flowers
no
yes
?
Variable-leaf watermilfoil (M. heterophyllum)
INVASIVE
5-12
2-4 cm long
4 to 6
0.5 - 3 cm long; larger than flowers; serrated/lobed
Hybrid watermilfoil (M. spicatum Ă&#x2014; sibiricum)
INVASIVE
8-19
1.5-4.2 cm long
?
?
Hydrilla verticillata (hydrilla)
Hydrilla Distribution
• Map of ID and WA and Monecious • eddmapp Dioecious
Primarily dioecious
Other Hydrocharitaceae Elodea canadensis (Canadian waterweed)
Elodea nutallii (Nuttallâ&#x20AC;&#x2122;s waterweed)
Egeria densa (Brazilian elodea)
Differentiating the Hydrocharitaceae Elodea sp.
Egeria
Hydrilla
(Native)
(Non-native, common in OR/WA)
(Non-native, unknown in OR)
Robert VidĂŠki, Doronicum Kf Bugwood.org
Potamogeton crispus (curly leaf pondweed)
Sastramoutomo 1981
Stuckenia pectinatus (sago pondweed)
Other Potamogetonaceae Potamogeton foliosus (leafy pondweed)
Potamogeton richardsonii (Richardson’s pondweed)
P. pusillus (small pondweed)
© 2012, Craig Althen
Potamogeton robbinsii (Robbins' pondweed)
© 2005, Ben Legler
© 2005, Ben Legler
Zannichellia palustris (horned pondweed)
© 2005, Ben Legler
Ceratophyllum demersum (coontail, hornwort)
• Whorled leaves • Serrated margins • Horn-like divisions
Ranunculus aquatilis (white water buttercup)
Š 2004, Ben Legler
Cabomba caroliniana (Carolina fanwort)
Isoetes spp. (quillworts)
Isoetes occidentalis
Š 2010, G. D. Carr
Isoetes nuttallii
Utricularia spp. (bladderworts) Utricularia vulgaris (common bladderwort)
Utricularia inflata (swollen bladderwort)
Callitriche heterophyllum (different-leaved water-starwort)
Callitriche stagnalis (pond water-starwort)
Callitriche hermaphroditica (northern water-starwort)
Callitriche palustris (vernal water-starwort)
Macroalgae Chara spp. (muskgrasses)
Chara â&#x20AC;˘ 6-16 branchlets, never divided; musky scent, tiny thorn-like projections Nitella â&#x20AC;˘ 6-8 evenly forked branchlets; no scent; smooth texture
Nitella spp. (brittlewort)
Floating Leaf Aquatic Plants
Nymphaea odorata (fragrant water lily) • Rooted aquatic perennial • 3-6 feet • Floating heart-shaped or circular leaves (30 cm); purplish underneath, leathery, deeply cordate • Large (6-12 cm) fragrant flowers; 20-30 petals, range of colors with yellow centers
Nuphar lutea (yellow pond-lily ) • Larger, oval to heart-shaped leaves with a prominent midvein • Flowers – yellow petals and centers, 9-petals
Nymphoides peltata (yellow floating heart) • Aquatic perennial • Depths of 2-13 feet. • Leaves heart-shaped to circular, 1 to 4 in long, purplish underneath with slightly wavy margins • 5-petaled, 1-1.25” diameter
© 2004, Sue Winterowd:
Brasenia schreberii (water shield)
Eichhornia crassipes (water hyacinth)
Ludwigia palustris (marsh seedbox)
Ludwigia hexapetala, L. peploides (water primrose)
Š 2005, Ben Legler
Azolla pinnata (feathered water fern)
Other azollas
A. filliculoides
A. mexicana
Emergent Aquatic Plants
Butomus umbellatus (flowering rush)
Aquatic perennial ď ŹMoving down Columbia River from infestation in Montana ď ŹLarge infestation in Yakima River
Butomus umbellatus (flowering rush) • Cluster of 20-50 flowers with 3 pinkish petals and sepals. • Leaves triangular at base, flattened above, but strong mid-rib. • Emergent leaf tips may be spirally twisted • Submersed leaves long, strap-like. • Strongly rhizomatous
Phragmites australis (common reed) ssp. australis
ssp. americanus
Phragmites Distribution in the Columbia Basin
Green = native Red = introduced
Warrenton, OR
Typha spp. (cattail) T. angustifolia (narrow-leaf cattail)
T. latifolia (broad-leaf cattail)
Invasives Lythrum salicaria (purple loosestrife)
Lysimachia vulgaris (garden loosestrife)
Phalaris arundinacea reed canary grass
ribbon grass
Iris pseudacorus (yellow-flag)
Myrophyllum aquaticum (parrot feather)
Hippuris vulgaris (common mareâ&#x20AC;&#x2122;s tail)
Importance of Reporting & Confirmation Many factors can complicate accurate identification, such as: • confusion with closely-related native species • hybrids (milfoils, pondweeds, etc.); • plasticity – physical characteristics (leaf shape or color) may vary due to environmental conditions
Suspected weeds should be reported ASAP! Delayed reporting/confirmation can result in: higher management costs reduced chances of eradication (Rejmanek and Pitcairn, 2002)
Remember, weeds are not alone out there!
Zebra and Quagga mussels Dreissena sp. • The name derives from stripes on the shell… • However you won’t always see black and white stripes
REPORT THIS SPECIES ASAP!
Report Suspected AIS
oregoninvasiveshotline.org or call 1-866-INVADER
www.pdx.edu/oregon-lake-watch 503-725-2937 or 503-725-9075