Category Archives: Aquatic Plants

Pond Weeds and Their Cousins: A Report from the Aquatic Plants Workshop

By the time I found room 246 in Hitchcock Hall, hidden behind construction barriers on the University of Washington campus, class had already begun. I crossed the room quickly to take a seat on a squeaky metal chair stationed behind a microscope.

Peter Zika stands ankle high in a lake, pulling up the stalks of an aquatic plant

Peter Zika in the field at an Aquatic Plants Workshop
Photo: Washington Native Plant Society

Peter Zika, a botanist specializing in the obscure, was halfway through a lecture on local aquatic plants. Before I aimed my attention at his slides on the screen, I glanced around at the dozens of plants standing in water-filled jars around the lab. I’d anticipated this class for months, and it was hard not to feel intimidated at the outset of this class on aquatic plants co-sponsored by the Washington Native Plant Society and the University of Washington Herbarium.

As a newcomer to aquatic plants, I had signed up for the class to get personal with plants underfoot in the wetlands and lakes of the Snohomish basin. The class offered an opportunity to examine common species, get acquainted with rare species, and review the invaders. At first it was overwhelming: long scientific names I could hardly pronounce, let alone spell. But gradually over two days of study, I would learn the characteristics and names of over 50 plants, and leave wanting to learn more.

After the slide show, Peter instructed us to gather wet samples from jars around the back of the room. Each jar was labeled with a 3 x 5 card with the scientific name of the plant it held. Peter helped us wade through the genera from Alisma to Zostera. He encouraged us to choose interesting specimens and place them in a paper bowl for viewing under a microscope. By keeping the sample wet, we would better see the characteristics of their filmy or feathery leaves.

Our class packet provided a list of aquatic plant families from the long-awaited update to the Flora of the Pacific Northwest or “Hitchcock.” It’s the authoritative technical manual that botanists worship in our part of the world.

Upright stalk of whorled green leaves with tiny yellow anthers visible in the axils

Flowering shoot of Myriophyllum hippuroides (western water-milfoil)
Photo: Ben Legler

During the workshop, we used common names only when they were easier to say. Introduced “frog bit” vs. Hydrocharis morsus-ranae, for example. Getting comfortable with scientific names takes practice, so Peter carefully pronounced each one for us as he pulled species from the jars and enthusiastically chatted up their characteristics like old friends.

As I glanced at the water-filled jars behind me, it was overwhelming. So many scientific names I didn’t recognize! Maybe I should start with something pretty? I reached into a jar and pulled out a short stem of Elodea canadensis, (common waterweed).

I placed it into the paper bowl, where it came alive under the scope. So different than when I’d seen it resting on a lake surface, with much of the plant held to the sediment below by fibrous roots. This Elodea is common to most wet shores in slightly brackish water.

For the rest of the morning, we wandered back and forth to the jars, selecting specimens to key out under the microscopes. We asked Peter for help interpreting vocabulary and visuals, questioning him about ascending and descending, veins and air sacs, traps and turions.

Turion was a word I’d seen referenced in eelgrass surveys, but our native eelgrass, Zostera marina, has no turions. A turion is an the overwintering bud that occurs in some aquatic plants; it allows the plant a head start the following growing season. But when we looked in Volume 22 of the Flora of North America we found no description of turions on eelgrass, only a reference to “shoots” present in sandy shorelines in spring and summer.

Peter’s rule was no wet hands near the field guides and copies of Hitchcock in the far left corner by the door. And definitely no wet hands near the neatly pressed herbarium specimens—each one unique—in cardboard and newspaper in the right corner of the room.
Throughout the morning we alternated between viewing plants under the scope, and gathering at the front of the room to examine delicate pressed herbarium specimens. One by one Peter selected similar-looking plants for us to compare.

floating leaves and flower stalk with yellow flower of swollen bladderwort

Utricularia inflata (swollen bladderwort); introduced in Washington State
Photo: Ben Legler

We worked our way through Haloragaceae family, the milfoils: Myriophyllum hippuroides, spicatum, sibiricum, verticillatum. We continuing through the Lentibulariaceae, the bladderworts: Utricularia gibba, inflata, intermedia, minor, vulgaris subsp. macroceras. Soon enough, the foreign words started to take shape on my tongue and I began to be able to tell the species apart.

In the afternoon I chatted with my neighbor, Jenn Andreas, a Washington State University Extension biological weed control specialist. She’d been exploring the zoological contents of her paper bowl. Early on, she found a little caddis fly larva building a cocoon right on a leaf of Stuckenia pectinata (broadleaf pondweed). Under the scope, this adorable critter went about its business building a home of algae, oblivious to our watchful eyes. Tiny brown leech-like worms scrapped between fronds of Potamogeton robbinsii (Robinson pondweed). There’s an entire world of activity that we can only see at 10x magnification or more.

The highlight of my day was learning how to press wet specimens. Peter demonstrated with Myriophyllum spicatum (Eurasian milfoil). He spread its leaves in a tub of water, gently slid archival paper underneath the leaves, and lifted the paper to drain off the water. He lay the sheet between newspaper, covered it with wax paper to keep the plant from sticking to the newsprint, and closed the package firmly, with a string tied over cardboard sheets.

After drying, this pressed specimen will be added to the University of Washington Herbarium, with a label indicating, date, location, neighboring species, and names of the collectors.

Peter then encouraged us to press specimens on our own, so I chose Potogameton natans (floating-leaved pondweed), a lovely native plant that grows in ponds and lakes across North America. The label for this specimen will read:

Potogameton natans
12 August 2016, Pierce Co., WA, Bauman Lake, Joint Base Lewis-McChord, Training Area #4, common with Utricularia vulgaris, Nuphar polysepala, P. Zika 28242 & S. Krock

Dried leaves and stems of pondweed, mounted on paper

A herbarium specimen of Potamogeton natans (floating-leaved pondweed)
Photo: University of Washington Herbarium

On the second day of the workshop we gathered back at the lab to look at pressed and live specimens before heading out to the field. This time, Peter insisted we spend time on the numerous pondweeds. More Potamogeton species went under my scope: alpinus, diversifolius, gramineus.

Our first field stop was the shoreline bulkhead behind the Mountaineers building on Sand Point Way in Seattle. We found and compared Egeria densa (Brazilian elodea) with Elodea canadensis (common waterweed), Potamogeton crispus (curly leaf pondweed) with P. richardsonii (Richardson’s pondweed) and P. praelongus (white-stemmed pondweed). Our group found Ceratophyllum demersum (raccoontail) in the shoreline wrack along the muddy beach as well as thick growth of several water milfoil species in a sheltered spot away from boat rudders and propellers.

Near the boat dock, Vallisneria americana (water celery), was busy sending up female shoots, patiently “waiting for a boyfriend” as Peter put it. The male shoots would rise to the surface, open three petals, and float away, the pollen-covered anthers acting as sails. Once on the surface, the male flowers drift until they find a slight indentation in the water created by the female flowers. Hours later, the fertilized ovary re-coils itself back to the base of the plant and creates a 2–3 inch tall cylinder. When the cylinder decays, the fertilized ovules—now seeds—are released into the water, eventually germinating into new plants.

Our next stop was Pine Lake, where we joined local Sammamish kids wringing out a few more days of late summer freedom before school began. We lined up on the dock, dangling our feet into the water as a group of female mallards cruised by. Here we found Potamogeton amplifolius (big-leaf pondweed) growing in abundance along the north side of the pier.

Our last field stop was the Tibbetts Creek delta on the southern shore of Lake Sammamish. Although trampled by feet and waves, the dense mud and sand still created a mecca for aquatic plants. Some uncommon native species grew here: Juncus diffusissimus (slimpod rush), Cyperus eragrostis (tall flat sedge), Heteranthera dubia (grassleaf mudplaintain), and introduced Lythrum hyssopifolia (hyssop loosestrife). We noted about 20 other species as well, such as Eleocharis acicularis (needle-spike rush), introduced Callitriche stagnalis (pond-water starwort), and Nuphar polysepala (yellow pond lily).

floating rosettes of green leaves

Callitriche stagnalis (pond-water starwort)
Photo: Clay Antieau

While we were there, Ben Legler, Informatics Specialist at the University of Washington Herbarium, collected several more interesting species. He gathered Isolepis setacea, (bristleleaf bullrush), Lysimachia vulgaris (garden yellow loosestrife), Echinochloa crus-galli (barnyard grass), and Lindernia dubia (yellowseed false pimpernel) to take back to the lab for further examination.

Around 3 pm, hot, tired, and sunburned, we filed back to the cars and vans for the return trip to the University of Washington. Who knew so many species of aquatic plants lived on our shorelines?

I drove home thinking about all that I had missed during my years as a state biologist focused on riparian corridor species: all the pond natives I didn’t record, all the invasives I failed to recognize. All of this plant life right there beneath my feet as I tromped through the fields of Phalaris arundinacea (reed canary grass) and Impatiens noli-tangere (touch–me-not).

Now that I have looked down, I won’t miss out again. I’ll be out there exploring the shorelines with few used Ziploc bags in my pockets for collecting—and an enlightened eye for new discoveries.

Editor’s note: Interested in future workshops? Join the Washington Native Plant Society and be among the first to hear about opportunities to delve deep into aquatic plants, grasses, bryophytes and more. 

A Few Upcoming Washington Native Plant Society Events

Gardening with Native Plants: The What, Why, How and Where

Wednesday October 12
7:00 pm
Bellevue Botanical Garden

Salal Chapter Native Plant Sale

Saturday October 15, 2016
10:00 am to 12:00 pm
WSU Research Center, Mt. Vernon, WA

Seed Ball Toss

 to 

Cranberries at  Mirror Lake Bog

Saturday, November 19, 2016
9:00 AM to 4:00 PM
meet at Whatcom Falls Park

MORE! Chapter Field Trips, Programs, and Plant Sales

Other Events

Sarah Reichard: A Celebration of Her Life

Thursday, October 13, 2016
2:00 pm to 5:00 pm
For details and updates see the UW School of Environmental and Forestry Sciences Offshoots blog.