Phragmites and knotweed growing together along highway drainage area, E. Stroudsburg, PA.

A dense stand of Phragmites australis growing along Highway 447, East Stroudsburg, PA, with a little competition from Japanese knotweed (Fallopia japonica), August 2004.

Common Exotic Aquatic Plants
The following plants have been found to be the most common exotic aquatics in Pennsylvania's lotic ecosystems by the Pennsylvania Flora project (www.paflora.org/Aquatic.html).  Many of the photographs were taken at a workshop (9/24/04) held by the Delaware River Invasive Plant Project (DRIPP) and The Nature Conservancy, Long Pond Office.  Illustrations come from the Plants Database (plants.usda.gov) and originally came from Britton, N.L., and A. Brown, 1913. Illustrated flora of the northern states and Canada. Vol. 2: 612, Courtesy of the Kentucky Native Plant Society.   Collections and identifications made by Tim Block of the Morris Arboretum, University of Pennsylvania are denoted by (*).   Collectons and identifications made by Jeri Jewett-Smith of ESU are denoted by (#). Click on the thumbnail for higher resolution photographs and/or illustrations.  More pictures will be added in the future.  Photographs were taken by Jeri Jewett-Smith and may be copied.
Potamogeton crispus, curly pondweed
 Potamogeton crispus line drawing from Britton and Brown, 1913.
Elatine triandra,  threestamen waterwort
 Elatine triandra line drawing from Britton and Brown, 1913.
Myriophyllum spicatum *, Eurasian water-milfoil
 Myriophyllum spicatum from DRIPP workshop.
Nymphaea (pink-flowered)

Lythrum salicaria #, purple loosestrife
 Lythrum salicaria close-up, from Ramapo Reservation, NJ.
 Habit view of Lythrum salicaria from Ramapo Reservation, NJ
Phragmites australis #, common reed
 Phragmites australis stand along Sullivan's Trail, near Scotrun, Pa.
 Close-up of flowering panicle of Phragmites australis in August.
Polygonum cuspidatum ( syn. Fallopia japonica) #,
Japanese knotweed
 Close-up of Japanese knotweed in August.
 Japanese knotweed along Crescent Lake Road, Scotrun, PA.
Trapa natans *
 Trapa natans from DRIPP workshop.
 Trapa natans fruit from DRIPP workshop.
Cabomba caroliniana

Hydrilla verticillata *
 Hydrilla verticillata from DRIPP workshop.

Last Update: August, 2004, JJS