Happy Halloween: ghosts in the landscape

Cotton grass (Eriophorum angustifolium) Single delight (Moneses uniflora) Wynn Nature Center, Homer, Alaska by Betsey Crawford
Cotton grass (Eriophorum angustifolium) Single delight (Moneses uniflora) Wynn Nature Center, Homer, Alaska

When I first thought of the title for this Halloween post, I had fun in mind — white flowers that have ghostly or skeletal effects — and there are those, like the cotton grass above and the trillium and others below. But the more I thought about white flowers, the more questions I had. How did they become white? Is it a loss of pigment or a color of its own? Why are there so many of them? Depending on the region, they can far outnumber flowers in the blue to red to orange range, and outstrip the numerous species of yellow flowers. Studies show that pollinators, given a choice, will gravitate to colors. So what’s the evolutionary advantage of white? Is there one? It turns out that white flowers are full of mystery. Which is, indeed, fun.

White flowers: Pacific trillium (Trillium ovatum) Blithedale Canyon, California by Betsey Crawford
The very ghostly newborn petals of Pacific trillium (Trillium ovatum) Blithedale Canyon, California

The earliest angiosperms, more than 100 million years ago, are thought to have been white, cream or pale green. Since Darwin, people — including me — have been happily saying that the more vivid colors slowly evolved to attract pollinators, whose vision long predated the flowers. And that appears to be true. Or, at least, there’s no strong body of evidence saying it’s not true. But, as it turns out, there’s no strong body of empirical evidence saying it is true. Empirical evidence implies that we can see something happen in real time, and it’s hard to see an evolutionary process in our brief lifespan. 

White flowers: Ghost flower (Mohavea confertiflora) Anza Borrego Desert, California by Betsey Crawford
This one is actually called ghost flower (Mohavea confertiflora) Anza Borrego Desert, California

There are studies that show, for example, flowers becoming redder in as little as a single generation as more hummingbirds pollinate them. Further studies show that when given choices, pollinators will choose colors over white flowers, though that may be because the colorful ones stand out more vividly against green foliage. Finding flowers efficiently is crucial to the success of both flower and pollinator, so the easier the flower is to see, the better. Very important, the stronger the relationship a pollinator has with a specific color, the more likely it is to bring matching pollen from one flower to fertilize another in the same species.

White flowers: Sitka burnet (Sanguisorba stipulata) Wynn Nature Center, Homer, Alaska by Betsey Crawford
Sitka burnet (Sanguisorba stipulata) Wynn Nature Center, Homer, Alaska

So, we know that pollinators have an intimate relationship with flower color. Or, more accurately, with the color’s wavelength, since the purple we see is not what the pollinator sees. But, with the explosion of genetic information in recent years, there’s also a growing appreciation for other factors that are at play, especially in how white flowers have evolved. Flowers in the blue to purple to red range use anthocyanins to create their color, the chemicals that make foods like grapes and raspberries so good for us. If the dominant anthocyanin is delphinidin, the flower is purple, if pelargonidin, red, if cyanidin, magenta to lavender. Other flavonoids, such as anthoxanthins, along with a variety of carotenoids, create yellows and oranges. 

White flowers: Single delight (Moneses uniflora) Wynn Nature Center, Homer, Alaska by Betsey Crawford
Single delight (Moneses uniflora) Wynn Nature Center, Homer, Alaska

In the course of mutations that alter the expression of specific enzyme and protein pathways, the amounts of these color-inducing chemicals can vary, changing the color of the flower. Mutations may also cause the pathways to stop working altogether. The resulting loss of function can return the flower to its primordial white, a state that’s likely to be irreversible since it would take a series of very specific mutations for those particular pathways to work again. 

White flowers: Sand lily (Mentzelia nuda) Smoky Valley Ranch, Oakley, Kansas by Betsey Crawford
Sand lily (Mentzelia nuda) Smoky Valley Ranch, Oakley, Kansas

There is a widely accepted division of flower/pollinator relationships: bees prefer flowers in the blue range, while hummingbirds gravitate to red, butterflies to pink, moths and beetles to white. And studies do back up these general preferences. But there’s a lot of variation. If bees weren’t interested in pollinating white flowers, we wouldn’t have almonds, apples, plums or any number of other fruits in the Rosaceae family. Thus, other factors are apparently important, among them scent, availability, abundance, learned behavior, competition, as well as the match of plant shapes to pollinator characteristics. It also may be that the subtle pinks that make white apple blossoms so poignantly beautiful to us are neon signs to bees. More mysteries. As every study says, ‘more research is needed.’

White flowers: Fried egg plant (Romneya trichocalyx) San Ramon, California by Betsey Crawford
Fried egg plant (Romneya trichocalyx) San Ramon, California

As fascinating as I find all this, I’m somewhat resistant to the idea that the gorgeous hues of reds, purples and lavenders I love so much are a result of ‘the number of hydroxyl groups attached to the B-ring of the molecule,’ or that tender, luminous whites are due to the functional failure of these groups. Reducing something as magical as color to the action or loss of enzyme and protein pathways seems like a comedown. On the other hand, my seeing and treasuring these colors is possible only because my body relies on similar pathways. Which brings another mysterious dimension forward: the fact that flowers and I share biological functions and genes, and, in sharing them, share each other.

White flowers: white thistle (Cirsium hookerianum) Waterton National Park, Alberta by Betsey Crawford
White thistle (Cirsium hookerianum) Waterton National Park, Alberta

Not only that, but without a strong connection to a variety of pollinating animals and insects, and the biology and genetics we have in common with them, neither flowers nor I would be here to begin with. All those pathways need constant nourishment. Like me, the pollinators depend on flowers for nutrition and survival. Flowers depend on these friendly forces, which can include me, for reproduction. We all depend on a huge array of microbes and fungi to create the nutrients we thrive on from the soil at our feet. We depend on the movements of air currents, the hydrology of water, the minerals released from rocks. 

Sitting among flowers on a forest path, or the desert floor, or out in a meadow, we’re held in a vast array of interlinking pathways, beating our hearts, feeding our cells; moving water, air, nutrients; creating color, vision, scent. All mysteriously designed to keep every one of us — flower, leaf, dirt, human, bee, bird, beetle — alive and blossoming. 

White flowers: White paintbrush (Castilleja occidentalis) Waterton National Park, Alberta by Betsey Crawford
White paintbrush (Castilleja occidentalis) Waterton National Park, Alberta

More beautiful white flowers can be found in the gallery Luminous Whites.

I’d love to have you on the journey! If you add your email address, I’ll send you notices of new adventures.

Related posts:

Globe flower (Trollius species) Manito Park, Spokane, Washington by Betsey Crawford
Happy Halloween: slightly
ominous, very orange
Tidy tips (Layia platyglossa) with California poppy (eschscholzia california) on Ring Mountain, Tiburon, California by Betsey Crawford
Wild abandon: the mystery
and glory of plant diversity
Autumn peach leaves at Genesis Farm, Blairstown, New Jersey, by Betsey Crawford
Samhain in New Jersey

 

10 thoughts on “Happy Halloween: ghosts in the landscape”

  1. So insightful and totally supports the Oneness of all Life. Thank you for the science and the beauty you bring forth in your writing. I’m grateful! XO

  2. I love how you link us to whatever aspect of nature you’re writing about — in this case the functioning of the enzymes and pathways. Of course, we’re part of nature, too, but many of us seem to forget that all too often. We’re all functioning in one major pathway together — and thanks for the reminders of this. ????????????

  3. This is all so fun and fascinating! I’m with you on the comedown of too much scientific knowledge getting in the way of appreciating simple inherent beauty. What came to mind as I was reading this was the term I’ve heard used in the cultivated natural world: moon garden, full of white flowers. Being a huge color freak myself, I’ve never planted one, but I imagine one on a full moon night and it would seem to be alive and even a bit spooky! Happy Halloween!

    1. Though I do love white flowers, I’ve never planted an all white garden, either for me or for a client, though I’ve seen some. But never by moonlight, which must be magical. Happy Halloween to you!

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