Weeds of Boise: Ridenbaugh Canal between Vista Avenue and Federal Way

Like so many urban areas that had their start as agricultural communities, Boise is home to a vast network of canals. Major canals, such as the New York Canal, stretch across the valley and divert water through an extensive series of laterals. This water once irrigated numerous farms and orchards found within Boise and beyond. While large farms still exist outside of Boise – as well as a few small farms within city limits – much of this water now goes to irrigating lawns and gardens of city residents who are lucky enough to have access to it.

Because of the way these canals weave their way throughout Boise and into the surrounding area, there is interest in transforming them into transportation corridors for bicyclists and pedestrians. This would be in addition to the Boise River Greenbelt, a 30 mile trail system that already exists along the Boise River, and would vastly increase access to alternative and sustainable transportation for people living in the area.

Accessibility to these canals is limited, but where trails are available, they are a great place to observe wild urban flora and urban wildlife. This month, I explored a section of the Ridenbaugh Canal that extends about a thousand feet between Vista Avenue and Federal Way. There is a wide, dirt trail on the north side of the canal, easily accessible from Vista Avenue, that ends at the railroad tracks which run alongside Federal Way. The bank of the canal is steep, but there is one spot at the end of the trail that leads down to the water’s edge. Weeds are abundant along both sides of the trail, so it’s a great place to become familiar with common members of our wild urban flora.

blue mustard (Chorispora tenella)

henbit (Lamium amplexicaule)

flixweed (Descurainia sophia)

A long strip of white top (Lepidium sp.) flanks a fence alongside the trail.

A pair of Canada geese and four goslings have made this stretch of the canal their home.

redstem filaree (Erodium cicutarium)

bulbous bluegrass (Poa bulbosa)

Japanese knotweed (Reynoutria japonica)

Weeds found at Ridenbaugh Canal between Vista Avenue and Federal Way:

  • Bromus tectorum (cheatgrass)
  • Ceratocephala testiculata (bur buttercup)
  • Chondrilla juncea (rush skeletonweed)
  • Chorispora tenella (blue mustard)
  • Descurainia sophia (flixweed)
  • Draba verna (spring draba)
  • Epilobium sp. (willowherb)
  • Erodium cicutarium (redstem filaree)
  • Galium aparine (cleavers)
  • Hordeum murinum ssp. glaucum (smooth barley)
  • Lactuca serriola (prickly lettuce)
  • Lamium amplexicaule (henbit)
  • Lepidium sp. (white top)
  • Malva neglecta (common mallow)
  • Medicago lupulina (black medic)
  • Medicago sativa (alfalfa)
  • Poa bulbosa (bulbous bluegrass)
  • Reynoutria japonica (Japanese knowtweed)
  • Rumex crispus (curly dock)
  • Secale cereale (cereal rye)
  • Taeniatherum caput-medusae (medusahead)
  • Taraxacum officinale (dandelion)
  • Tragopogon dubius (salsify)

Like all posts in the Weeds of Boise series, this will be updated as I identify and photograph more of the weeds found in this location. If there is a canal near you, get outside and take a look at what’s growing along the banks. Let me know what you find in the comment section below.

Summer of Weeds: Henbit and Purple Deadnettle

There are weeds for every season. Now that we are heading into the hot days of summer, spring weeds (if they haven’t already) are fading. There is a parallel between them and the spring wildflowers we love. They start early, greening up and flowering even before there are leaves on the trees. They exploit the sun made available before deciduous trees and shrubs can hog it all, and they take advantage of the moisture in the soil brought by winter snowfall and spring rain. They thrive in cool temperatures, and their flowers provide early pollen and nectar for emerging pollinators. One major difference between spring ephemeral weeds and spring ephemeral wildflowers is that, despite having similar strategies and providing similar services, the spring weeds aren’t from here; and so we look down on them.

Two common, annual, spring weeds that are easily recognizable – but often mistaken for one another – are henbit and purple deadnettle. Both are in the genus Lamium and the family Lamiaceae (the mint family) and both arrived from Europe. Looking closely at the leaves is the best way to tell these two apart. The upper leaves of henbit (Lamium amplexicaule) lack petioles and are round or oval with rounded teeth. The upper leaves of purple deadnettle (Lamium purpureum) are crowded around the stem, have short petioles, sharper teeth, and are more spade-shaped, coming to a point at the tip. The uppermost leaves of purple deadnettle are a distinct reddish-purple. Identify That Plant offers a great tutorial to help tell these and groundy ivy (another spring-occurring, annual weed in the mint family) apart.

henbit (Lamium amplexicaule)

Henbit prefers full sun and moist, rich soils. It can have either a prostrate or an erect growth habit. In urban environments it is commonly found in lawns, garden beds, and drainage ditches. It is common in agricultural crops and fallow fields as well. According to Weeds of North America, “henbit is poisonous to livestock, especially sheep, causing the animal to stagger;” it is also a host for aster yellows, tobacco etch, and tobacco mosaic viruses. Purple deadnettle inhabits similar sites, often forming a dense groundcover. While henbit and purple deadnettle are highly attractive to bees, they do not always require insect pollination and can self-pollinate instead. Each plant can produce dozens of seeds, and seeds remain viable in the soil for as long as 25 years.

Plants in the genus Lamium are commonly referred to as dead-nettles because they resemble stinging nettle (Urtica dioica) and other plants in the genus Urtica. Lamiums do not posses the stinging quality, and so they are “dead.”  The young leaves, shoots, and flowers of henbit and purple deadnettle are edible and can be eaten raw or cooked. Check out Eat the Weeds for more details.

Illustration of henbit (Lamium amplexicaule) from Selected Weeds of the United States (Agriculture Handbook No. 366) circa 1970

More Resources:

purple deadnettle (Lamium purpureum)

Quote of the Week:

From Wild Urban Plants of the Northeast by Peter Del Tredici

From a utilitarian perspective, a weed is any plant that grows by itself in a place where people do not want it to grow. The term is a value judgment that humans apply to plants we do not like, not a biological characteristic. Calling a plant a weed gives us license to eradicate it. In a similar vein, calling a plant invasive allows us to blame it for ruining the environment when really it is humans who are actually to blame. From the biological perspective, weeds are plants that are adapted to disturbance in all its myriad forms, from bulldozers to acid rain. Their pervasiveness in the urban environment is simply a reflection of the continual disruption that characterizes this habitat. Weeds are the symptoms of environmental degradation, not its cause, and as such they are poised to become increasingly abundant within our lifetimes.

A patch of dead-nettle (Lamium sp.) – photo credit: Amy Trampush (Thank you, Amy!)