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Spring blooms with wildflowers in Sonoma County

“…thou canst not stir a flower without troubling of a star.”

Francis Thomson, English poet

Few spring sights in Sonoma County are as uplifting as the faces of the flowers that decorate our hillsides and valleys in a palette of lavenders and dark purples, creamy yellows and oranges, pinkish whites and everything in between. What we call the “early spring” wildflowers — like our delicate milkmaids and nodding shooting stars — actually begin to show up in the North Bay region in January and February, sometimes even December. Mid-March, however, is the main event. What better excuse to get outside with a sketchbook, or a camera, or just an appreciative eye.

Whatever your own floral favorites, it is humbling to remember that flowers are not only beautiful but essential: we owe them a great debt. As so eloquently described by anthropologist and naturalist Loren Eisley in his 1946 essay “How Flowers Changed the World,” without flowers, the world as we know it — including the emergence of humans — would never have existed. To appreciate this connection that ties us to the emergence of flowering plants, we must look not only at a flower’s pretty face, but deep into the core of its being.

What is a wildflower?

There are as many definitions of wildflower as there are books or websites that feature them. Typically, wildflower watchers tend to focus on herbaceous annual plants with showy colorful petals. Grasses get left out because their wind-pollinated flowers lack petals and although beautiful in their own right, they are difficult to see with the naked eye. Strict native plant enthusiasts will rule out flowers that are not native to California, like the famous (or infamous, depending on one’s viewpoint) field mustard that paints Wine Country yellow in February, but originally arrived in California with the early Spanish settlers.

A narrow focus on the colorful cuties, however, leaves out the majority of flowering plants. From the weed in a sidewalk crack to a towering oak with its dangling pollen flowers called catkins, flowers are everywhere you look in nature. For my part, I will look deep into the face of any flower because each of them tells an amazing story. As for defining wildflowers, I do draw the line at ecosystem-destroying invasive species like the field marigold or vineyard calendula (Calendula arvensis) that is invading our natural areas to the exclusion of other species.

What do you see?

Flowers come in so many colors, shapes, and sizes that it’s hard to believe they all evolved from the same four sets of structures — the sepals, the petals, the male reproductive parts (the stamens) and the female reproductive part (the pistil). In a simple flower, like a milkmaid or a buttercup, each of these sets of structures is distinct and easy to observe. The sepals are the outer-most structures, often but not always green, whose job is to protect the flower when it is in bud. Then come the petals which are often, but not always, showy and colorful, whose job is to attract a pollinator. Inside the petals are the stamens with their pollen-producing anthers on top and at the center of it all is the pistil.

Over evolutionary time, flowering plants have used these basic building blocks to create a diversity of blooms that boggles the mind. The next time you go for a walk in one of our local parks, take a hand-lens (or even better, close-focus binoculars) and look closely at an iris, or a lupine, or any kind of daisy. It’s difficult if not impossible to distinguish four distinct sets of structures. Some flowers are exclusively male or exclusively female, thus lacking stamens or a pistil, respectively. In others, petals and/or sepals are fused into elongated tubes to attract specialist pollinators like hummingbirds or butterflies. The flowers of our local sky lupine (Lupinus nanus) hide their reproductive parts inside a pea flower, part of which changes color after being pollinated. The result? Increased efficiency for foraging bees who are directed by color to seek nectar only from those flowers that have yet to be visited. In blue dicks (Dichelostemma capitatum) the stamens are fused into a tiny white crown that hides the pollen inside. The trap-like flowers of Dutchman’s pipe (Aristolochia californica), which lack petals altogether, are formed from fused sepals. With an odor similar to rotting flesh, the pipe lures tiny flies inside and only releases them after the flower is pollinated.

Orchids have taken the art of floral architecture to unbelievable extremes. A whole group of orchids mimic female wasps or bees, thus duping pollen-laden males to attempt to mate with the flower.

Few flowers are as deceptively complex or evolutionarily successful as those in the sunflower family (also commonly called the aster or daisy family). With well over 20,000 species worldwide, the sunflower family is rivaled only by the orchids for global species diversity. These seemingly simple blooms include everything from the ubiquitous dandelion to the rare Sonoma sunshine (Blennosperma bakeri), an endangered vernal pool plant found only in Sonoma County. We have tarweeds, tidy tips and thistles; goldenrod, goldfields and gumplant; marigolds and mule ears; and hundreds of what frustrated amateur botanists like to call DYCs for “damn yellow composites” because so many are maddeningly difficult to identify.

The secret to the success of the sunflower family indeed lies in their composite nature. When you peer into the eye of a daisy, you are not seeing one flower but many crowded together. What we think of as petals in a sunflower are actually each a separate flower. When you blow on the fluffy head of a dandelion, you are scattering seeds made by hundreds of individual flowers. With many flowers arrayed on a single head, a composite flower is a one-stop shop for a pollinating insect. Like the complex strategies of orchids to attract pollinators, this ingenious design has proven to be highly efficient and therefore evolutionarily successful.

Flowers, fruits and evolution

It is so easy to get swept away by the sheer beauty and diversity of flowers, we tend to forget they are more than just a plethora of pretty faces. The job of a flower, after all, is to make a fruit containing the seeds to perpetuate the plant. All flowering plants make fruit and these fruits are as diverse as the blossoms from which they grow. In our local woodlands, acorns, buckeyes and the berries of everything from poison oak to madrone are all fruits.

The pea-like pods of our lupines and clovers and redbud trees are fruits. In the grocery store, any piece of produce that contains seeds is a fruit, regardless of where in the store they are displayed. A tomato, green bean, squash, pepper or avocado is as much a fruit, botanically speaking, as an apple, orange or banana.

Fruits are formed by the female part of a flower — the pistil. At the base of the pistil is a chamber called the ovary. Seeds are formed from ovules inside the ovary. After a flower is fertilized, the ovary wall develops into the fruit that protects the seeds inside.

The importance of flowers and their fruit to the evolution of life on earth cannot be overstated. Scientists disagree about when exactly flowering plants first evolved, with estimates ranging from 125 to over 200 million years ago. We do know from the fossil record that once established, flowering plants took over the land within a geological blink of an eye (on the order of tens of millions of years rather than hundreds). Indeed, so sudden was their appearance and explosive their spread that even Charles Darwin was vexed by what he called this “abominable mystery.”

Think of it. Flowers took a few basic building blocks and developed thousands of unique structures and strategies to reproduce. Colors and nectars evolved to attract specialized pollinators that opened up new niches for more species of insects and birds and bats.

Edible fruits recruited herbivores of all types to disperse seeds across both land and sea. High-calorie seeds and fruits rich in oil fueled the development of animals with increasingly high metabolic rates. The fruits of grasses (grains) became the staple food of humans worldwide. And here we are, awaiting spring, owing an immeasurable debt to the flowers.

Jeanne Wirka is an interpretive naturalist and resident biologist at the Bouverie Preserve near Glen Ellen.