Last month I was scuba diving in Grand Cayman and Bonaire, doing research for my next book. (Tough life, I know!) Before I left, I did two radio interviews about A Garden of Marvels. You can find my conversation with Leonard Lopate at WNYC in New York at http://www.wnyc.org/people/ruth-kassinger/. I also spoke with Tom Hall at Maryland Public Radio. That conversation is available for listening at http://wypr.org/post/secret-lives-plants. And the Audobon Society Magazine listed A Garden of Marvels as a great book for nature lovers for summer reading.
Last week I was in Maine, talking with Larch Hansen of Maine Seaweeds. I joined him for four hours of seaweed collecting (more research). The photo is of Larch pulling in kelp. Heavy work, but Larch has been doing it for 40 years. He’s about to celebrate his 70th birthday.
The Azolla fern isn’t much to look at. It has tiny leaves and floats en masse on top of water . Many people consider it a watery weed: it can cover the entire surface of a lake or pond, choking off sunlight to other water plants. No one thinks swimming with Azolla is fun.
But Azolla is a miracle plant. The Scientific American just reported that 55 million years ago (ten million years after the end of the dinosaurs), when carbon dioxide levels were much higher than today and the Earth was much warmer, the Azolla fern came to the rescue. The Arctic Ocean was a big inland lake at the time, hot and overloaded with nitrogen. The evidence is that the fern grew abundantly in the lake, and when the seasonal rains fell, the Azolla spread out over the surrounding continents. As the ferns photosynthesized and grew, they sucked up carbon dioxide from the atmosphere in great quantities. During dry spells, the ferns died and their remains (and their carbon components) settled onto the land and became buried under sediment. This boom and bust cycle went on for a million years, and during that period, atmospheric carbon dioxide levels dropped by roughly half. Author Jennifer Huizen raises the question of whether Azolla might play a role in countering global warming today.
That’s not the only great thing about Azolla. I’ve been digging into algae (sometimes literally) and discovered that rice, Azolla, and algae are linked. Paddy farmers plant Azolla in the water next to rice plants. The ferns have symbiotic blue-green algae that help the ferns absorb nitrogen. The nitrogen is passed along to the rice plants, increasing their productivity significantly.
There are more great things to be said (and I will say them next week) for Azolla. But let me say this: It’s a weed we need!
In Holland between 1634 and 1637, tulip bulbs that produced flowers with irregular stripes, streaks, and feathery patterns cost thousands of dollars. But those who bought the tulip bulbs in this era of tulipomania were regularly disappointed. They discovered that the seeds of the bulbs didn’t produce tulips that were “broken,” as these bi-colored flowers were described. Moreover, each season, the bulbs’ flowers were fewer and weaker. Although the little bulbs that grew off the parent bulb (called offsets) produced broken flowers, the next-gen bulbs were always less productive than their parent.
It turned out that the source of the spectacular patterns was one of the dozen tulip viruses. Unfortunately, the virus weakened the plant, and ultimately the genetic line of a bulb would die out.
In the early 1980s, the Dutch government outlawed the sale of virus-infected tulips. But the flowers pictured here are not illegals. Today’s tulip breeders have manipulated the genetics of tulips to produce patterns, so you can buy bulbs that produce flowers that recall the seventeenth-century beauties, but will bloom exuberantly for many years.
I’m delighted to note that the New York Times Book Review of Sunday, April 27 included A Garden of Marvels in its “Shortlist.” You can read the review at http://www.nytimes.com/2014/04/27/books/review/the-gardener-of-versailles-by-alain-baraton-and-more.html?ref=book!
This is the season for Robert Frost’s beautiful “Nothing Gold Can Stay”:
“Nature’s first green is gold,
Her hardest hue to hold.
Her early leaf’s a flower;
But only so an hour.
Then leaf subsides to leaf.
So Eden sank to grief,
So dawn goes down to day.
Nothing gold can stay.”
For me, the poem captures how swiftly we humans leave behind our completely innocent childhoods and move into more knowing adulthood.
In a botanical sense, though, Frost got it wrong. The yellows (as well as reds) that he sees in early spring leaves come from the carotenoid and anthocyanin pigments that are always in the leaves. In spring, the green chlorophyll pigment develops and soon dominates, and we can no longer see the other hues. Nonetheless, those colors are still there, which means that the gold does stay. This fact becomes apparent in fall after chlorophyll disintegrates and the yellow and red hues are visible again. My interpretation? Innocence and its close attendant, wonder, never leave us, even if they are harder to access in our maturity.
My book group read Rebecca by Daphne du Maurier this month, and we were all surprised by the descriptions of deeply fragrant azaleas at Manderlay in Cornwall. Around Washington, DC, the azaleas we know, while beautiful, are unscented. Why?
Azaleas are members of the rhododendron genus, and are closely related to the woodland rhododendrons. Most azaleas with scent are deciduous, so they lose their leaves in the fall. Most unscented azaleas are evergreen. Around Washington, DC, azaleas are often used as foundation-hiding plantings, so the evergreen (and therefore unscented) varieties are more popular.
About 1900––a few decades before du Maurier wrote Rebecca––Lionel de Rothschild fell in love with deciduous azaleas and bred his own cultivars at his Exbury estate in Hampshire (not far from Cornwall.) Some of the “Exburys” are particularly fragrant, so the second Mrs. de Winter may well have been entranced by Exburys.
This year, we lost a number of backyard shrubs to a particularly cold winter. I’m looking at deciduous azaleas as replacements. Not only do they provide fragrance, their leaves turn shades of bright orange, yellow, and gold in the fall.
“Leaves of three, let it be”: that’s the old mnemonic warning for avoiding poison ivy. Spring is the worst season for running into the plant, or rather the sap it carries in the cells of its leaves. That’s because the new leaves, which are often reddish, are particularly thin and fragile. A light touch can breach the cells, releasing the toxic urushiol inside.
For those of us on the East Coast who curse the white-tail deer for browsing our gardens, decimating forest underbrush, and make driving hazardous, we can thank them for one thing. Deer are unaffected by poison ivy oil, and happily chow down on the leaves.