Useful Nonnative Plants

Two Redbuds

Early in March, the Redbud is ready to burst into bloom; the beautiful zig-zagging tracery of its branches soon to be disguised in a cloud of pink flowers. I’ve planted several redbuds in different areas on our property, but the most spectacular is a well-developed small tree, now about 15 feet tall, in my front border. As it happens, it is an eastern Redbud (Cercis canadensis), a beautiful case of a mistaken identity!

Thinking About Weeds and Wildflowers

Micro-Habitats; Knowing Your Land

My husband and I live on a south facing hillside situated above the Novato Creek floodplains; it’s a beautiful, warm, and sunny spot with a great vantage point. Our hill, called Cherry Hill on some maps, is a part of one of the ridges extending from Mt. Burdell, the 3rd highest peak in Marin County, and we’re directly facing Big Rock Ridge, the 2nd highest spot in Marin. When the skies are clear, we can actually see just a little tip of Mt. Tamalpais, the highest peak in Marin! To the east, we can see the twin peaks of Mt. Diablo, which is the highest peak of all in our area and therefore the base meridian of much of northern California.

The views are wonderful here on our land, but the rainfall is sometimes disappointing; while other places in Marin are measuring and inch or so, we might get ¼ of an inch of rain! We’re in a rain shadow; I can see all the rain falling on the north side of Big Rock Ridge and in Indian Valley, but the clouds are often blown east. If they do get to our side, there’s not much moisture left. 

Even so, with not much more than an inch of rain, I’m witnessing an almost instantaneous re-greening of the landscape! Within days thousands of seeds are germinating; lots of grasses, and a great variety of weeds and wildflowers. This is where the fun begins. I love the challenge of identifying these minute plantlets. Sometimes I’m already so familiar with the plant that I know it from the cotyledons, but very often I need to see the first true leaves before I really know what they are.

Thinking About Weeds

Annual grass seeds are amongst the first to germinate, and of course wild oats (Avena species) are well represented. Wild oats, very different looking than the native Oatgrass (Danthonia californica) were introduced from Europe and brought to California, most likely with the very first Spanish settlers who brought livestock, and with them the seeds of these grasses. In Europe, during the olden times, the leafy new spring growth of one wild oat species (Avena sativa) was used as a medicinal to treat various conditions, including diminished sex drive. This is where the term "sowing one’s wild oats" originates from!

Along with the annual grasses come lots of thistle seedlings; their cotyledons are large and somewhat spoon-shaped. I can identify Italian thistles (Carduus pycnocephalus) easily when the first set of small and somewhat spiky, medium-green true leaves have developed. Some of the non-native weeds, including thistles, that plague wild areas in Marin, are thought to have been brought to the county by Samuel P. Taylor in raw materials for his paper mill. At first there was plenty of wood pulp locally available, but as those sources dwindled, and while the demand for paper kept going up, he also made paper using rags that were imported from Europe. It’s within these supplies that the seeds of some European weeds are thought to have "hitched a ride".

Here’s where my thoughts about weeds differ from those of many others; weeds are not all bad! 

Useful Nonnative Weeds

I’d bet that we’re all pretty happy that the rainy season is over and cherishing the beautiful sunny days. With a good layer of mulch to help retain moisture in the soil, plus the warm days, plants are now putting on growth that can almost be measured day by day!

Making Space for Weeds

The Flickers have now left my oak woodlands and moved to higher elevations in the Coast Ranges; I’ll look forward to seeing them again when we’re camping in the forests this summer. Meanwhile, the Tree Swallows are here already and I’m waiting to hear the first calls of the Ash-throated Flycatchers as they arrive from wintering grounds in Baja California. For the last five or six years they have shown up about the fifth of May, and by June are raising a brood in the nesting box hung in an old Coast Live Oak.

Some Other Common Brushfoots (Nymphalidae)

The Mourning Cloak  (Nymphalis antiopa) is fairly common in Marin, and adults can be seen flying almost any time during the year. This species is also found in Europe; on the British Isles it is known as the Camberwell Beauty, and considered the rarest of British butterflies. In Marin we see this butterfly throughout the year; in more inland areas the adults migrate to higher altitudes in summer, and disperse again downslope in the fall.

The Swallowtails

Within the family Papilionidae are some of the largest and most spectacular butterflies in the world. Four species are commonly seen in Marin; each one associated with a particular type of habitat. Three are yellow with black markings; the Western Tiger Swallowtail, with a nearly 4" wingspan is the largest butterfly in Marin; and the Pipevine Swallowtail is the only large 'blackish' butterfly in Marin. 


The "Whites"

One of the most common butterflies we see around Marin is the Cabbage White; and it has the distinction of being the only naturalized exotic butterfly in our area. This species has successfully established itself over the entire continent since its apparent introduction from Europe into southeastern Canada in the mid 1800's.  Most likely it was imported as larvae, hidden within the leaves of a cabbage plant. People called them 'cabbage worms', and since they fed on food crops, they were considered pests.

The Other "Ladies"

There are three closely related 'Ladies' that are easy to provide for in a habitat garden; the Painted Lady, the American Lady, and the West Coast Lady; however, they are not always easy to tell apart. Personally, I’m happy to see any and all of the butterflies coming to my garden for resources, and when I notice a medium-sized orangey butterfly I can be pretty sure it is one of the ‘ladies’. They often don’t sit still long enough, or with their wings held just so, to easily identify the characteristic field marks.

Painted Lady Butterflies

The Painted Lady (Vanessa cardui) is the most cosmopolitan of all butterflies on earth. This butterfly is widely distributed all over the Northern hemisphere, and can be seen in all types of habitats except dense forests. Painted Ladies lay their eggs on many different plants, and their larvae feed on a wider variety of plants (polyphagus) than most other butterfly species.

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