Ah, the bittersweet moments near the end of the summer. The nights are starting to cool, but the lake is still an incredible 76.5 degrees, at least here in Burlington, and the first of fall colors are poking into the green canopy. In this series, we celebrate the rainbow of fall (though a bit out of the ROYGBIV order) and explore the reasons behind the different colors we see in plants.

Blue: the invisible color

I re-read Homer’s epic poems, the Odyssey and Iliad, while I was studying abroad in Greece. From my apartment balcony on the hazy slopes of Athens I could look out to what Homer described as the οἶνοψ (oinops) or “wine-dark” sea. That phrase stuck out to me. When Helios’s chariot dipped below the horizon at dusk or Poseidon was in a mood, the white wake of large boats moving in and out of the port in Piraeus contrasted sharply against the nearly black waters. The view was more delightful, though equally intoxicating as retsina wine. I knew what Homer meant.

Ulysses (Odysseus) and the sirens by Herbert James Draper (1679) Odysseus and the sirens by (1679)

The phrase may have slipped away had Homer not kept using it. The epithet occurs no less than five times in the Iliad and twelve times in the Odyssey. Poseidon is a fickle god, and the Aegean and Ionian Seas shift between many colors. A briny cerulean, stormy azure, Poseidon-touched lapiz lazuli, or tranquil cobalt would do just as well to describe those mysterious and impenetrable waters. So why was it always wine-dark?

A sunset view of the Aegean Sea's "wine-dark" waters from Türkiye (from Wikimedia)

The scarcity of blue

There’s a pervasive and persistent myth that the Greeks didn’t have a word for blue. Yes, Homer loved “wine-dark,” he also described the brilliant and shining sky as bronze (bronze oxidizes to a matte teal color, which can be quite similar to the tones of a bright blue sky). But he was a poet, not colorblind (William Gladstone, who we’ll meet in a minute, incorrectly hypothesized that all ancient Greeks were colorblind). In other ancient Greek texts we find dark blue as κύανος (kýanos), which gives us the English cyan (if you don’t know the word cyan, check the name of your blue ink cartridge in your printer), and light blue as γλαυκός (glaukós) – in botany, glaucous describes any structure coated in a waxy bloom that is bluish or whitish and easily rubs off.

Lateral bud of boxelder with waxy bloom coating twig (Centennial Woods, Burlington)

Not surprisingly, I wasn’t the only person to notice the oddness of this phrase. Former British Prime minister William Gladstone wrote of the prevalence of “wine-dark” and absence of plain ol’ blue seas in his 1858 book, Studies on Homer and the Homeric Age. Later linguists noticed that Homer wasn’t the only one shy on blue. The color is absent in many other ancient texts from around the world and is even somewhat absent in some modern language groups, like the Himba tribe in Namibia (for them, blue is a shade of green; even our own word blue derives from black). Psychologists have shown that the lack of a word for a color lends itself to an inability to see that color, not physiologically, but a dulling of the senses towards that color’s uniqueness. There’s a consistent trajectory in the developing of color words in a language. It always starts with black and white then red followed by yellow. And blue is always last. This is likely because colors tend to have a name only once they are commercially or culturally relevant, like when it becomes a color that can be produced as a dye or pigment. Blue is exceedingly difficult to produce, and so blue seems to be a difficult color to discern in the wild world.

Loulaki powder is made from talcum and limestone

As a side note, there is some evidence that epithets like wine-dark seas or gray-eyed Athena were simple phrases that easily fit into the rhyme scheme bards used when reciting these epic poems. Bards performed long poems over what could be many hours (at an average pace of 300 words per minute both the Iliad and Odyssey take about 7 hours to read). Much like a freestyle rapper might have a set of short phrases in their back pocket to use as filler while they think of their next rhyme, so too having these short building blocks epithets could keep the recitations fluid and lyrical (they were often accompanied by instruments). I’m no freestyle rapper, but I can certainly remember the lyrics to a song with more ease than a recipe for cookies. Even still, wine-dark remains a bit odd, particularly since the word blue is not uttered a single time in either poem.

Lack of blues in nature?

The linguistic delay in developing descriptors of blue may be associated with this relative dearth of blues in the natural world. I still have a tough time swallowing this one though. Zeus’s domain, the sky, can be blue, as can Poseidon’s. But wouldn’t it be helpful to discern a calm blue sky from the roiling tumult of a dark gray curtain of clouds? Or wouldn’t it be nice to say, wait until the fruits have shifted from green to blue before harvesting. There are also edible fish and some marine mammals that are blue. Less culturally significant, but still aesthetically pleasing would be to describe the blue flanking a mature baboon, the feathers of jays, bluebirds, herons, indigo buntings, swallows, kingfishers, etc., the wings of some butterflies and the bodies of some dragonflies. I’ve come across blue beetles, blue amphibians, and blue seashells. My bruises turn blue, I have blue eyes, and I’ve made small clay pots from hydric soils that are bluish. It’s hard to imagine a world without words to describe these many prominent blues in the natural world. But again, it’s not that words for blue didn’t exist in the world’s lexicons of antiquity, just that they were late to the scene and not as culturally important since they couldn’t be produced as easily.

Lack of blues in plants

A blue rose seen in a dream is frequently interpreted as something that may be wished for but will never be fulfilled. While blue roses were finally cultivated in 2004 (Blue Rose Project), true blue flowers and fruits are quite rare in nature. Less than 10% of plants have some blue-like pigment and not surprisingly blue is really only found in flowers and fruits (there are some tropical understory plants with bluish leaves). By some long stretch of the imagination, musclewood is also called blue beech as the bark is, I don’t know, not quite gray, but bluish? There are plenty of blue-like things, like the lavenders of chicory (image below) or just really dark purple (like the blue-esque fruits of blueberries or juniper cones).

Blue in flowers

Bumblebee pollinating a chicory flower (Centennial Woods, Burlington)
Blue in flowers

The brilliant blue flowers of Siberian squill (see image below) are the first flowers to emerge in my backyard early in the spring. They hum with honeybees and bumblebees. A keen-eyed beekeeper may notice bees returning with blue pollen affixed to their legs during the short couple of weeks when squill is flowering. There are repeated patterns in the combination of flower shape, nectar concentration, scent, and color that correspond to the type of animal that pollinates a flower. called pollination syndromae. Deep tubed, red flowers with high concentrations of nectar tend to attract hummingbirds (which is why hummingbird feeders are red), while white, aromatic flowers are often pollinated by moths. And blue and purple flowers tend to be pollinated by bees (while flies can only see ultraviolet and green, bees can perceive ultraviolet, blue, and yellow). It’s late summer, and the roadsides are buzzing with bees slurping up nectar from goldenrods and chicory and to a lesser extent purple vetches and clovers.

A meadow of Siberian squill flowers (Backyard, Burlington)
Blue in fruits

Edible fruits have to signal to animals when the fruits are ripe. To do this, they produce enzymes which break down chlorophyll in the skin of the fruit and it shifts from green to a brighter color that contrasts sharply with the green foliage, like blue or red. Blue isn’t a pigment that plants produce on their own, but rather develops from a chemical reaction between anthocyanins (anthos: flower, cyan: blue) and an acid. Take a bunch of frozen blueberries and put them in a bowl. The residue will be red. Put in some tap water, which is slightly acidic, and the color will turn blue (video). Most blue fruits are so dark that they’re more aptly described as black or very dark purple (as in blackberries, black raspberries, blueberries, juniper berries, grapes, Virginia creeper, and buckthorn, and so on). Dark fruits are common in late summer as the plants cease growth, put a last flush of their energy reserves into fruit production, and then switch to starch storage in preparation for fall.

The developing fruits of a common buckthorn are still green before ripening to black (Casavant Natural Area, Winooski)

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