Cucumber curl around frame.

Cucumber tendrils curl around their support frame.

If a global pandemic disrupts food supplies, I’ll be ready — at least that’s what I told myself when I planted eight cucumber plants. Yes, there’s a story lurking here of mismanagement, poor planning and my inability to pick just one variety of cucumber; I’ll save that for another day.

Today’s story starts with a gift my gardening father gave me many years ago, a ball of twine. He knew my secret: What I really wanted for Christmas that year was a load of compost rather than another sweater. He couldn’t get my mom to agree about the compost, so the twine was a fine substitute.

Twine, done right, makes most gardening projects better. My dad’s ball of twine came in a simple tin with a hole at the top keeping it dry and untangled as it rolled around in my gardening tote.

Soft enough to keep young steams in line without gouging them, strong enough to hold exuberant tomatoes to their frames, this twine helps me keep my garden tidy. Each year I peek inside its tin to assess how much twine I have left to devote to garden projects — this year, I fear my supply is shockingly low.

Readers, you have patiently endured my lamenting the size of my small garden; it’s tiny, a wee patch into which I regularly stuff and then subsequently remove way too many plants. Eight cucumber plants won’t possibly fit in the 15’ x 3’ cold frame I have for veggies. Not unless I go up, way up.

I’m rather proud of my solution, I’ve cobbled together a trellis from castoff metal frames and bamboo poles. But I nearly ran though my twine supply building my vertical masterpiece.

Thankfully, my cucumber plants don’t need assistance climbing; no need for more of my dwindling supply of twine to support them — their tendrils pull them ever upward.

Specialized stems, called tendrils, use a form of touch to support the plant. Referred to as thigmotropism, touching unleashes a series of cellular-level chemical reactions enabling the tendril to change shape and curl around structures it encounters.

Contacting hard surfaces, the tendril’s cells open their calcium channels shifting the electrochemical balance across the cell wall, causing it to curve. Scientist believe plant hormones, auxin and ethylene, are also involved in thigmotropic behavior, but their role is unclear.

Back in the 1990s, researchers working with cucumbers discovered the growth of tendrils slowed on the side that was touched and sped up on the opposite side. This resulted in the tendril curving toward the surface it encountered. Impress your friends with your botanical knowledge — a plant’s ability to modify its growth rate is its thigmo mechanism, when it occurs in response to a stimulus it is a thigmo response.

Inspecting my cucumbers with my husband, we gazed up at the tendrils pulling the vines skyward. “Ah, the thigmo response in action,” I muttered, reaching out to redirect a tendril. I could tell, he was impressed; but it could have been the thought of fresh cucumbers heading toward our dinner table — who can tell with husbands.

We’ve long been puzzled by the movements of seemingly sedentary plants. Charles Darwin one of the earliest scientists to explore the topic, published in 1865 his comprehensive monograph, “On the Movement and Habits of Climbing Plants.”

More than 100 years later, scientists grow plants on the International Space Station to better understand their ability to move in response to light (phototropism) and gravity (gravitropism).

Back here on earth my cucumbers continue to send their tendrils across the frame I’ve constructed. Each morning I’m out inspecting their progress, marveling at how tightly they’ve bound themselves to their supports. Thanks to the thigmo response I can save the last bits of my twine for other gardening projects.

Absent from their gardens, Kit and Lise enjoy roaming our region exploring the intersection of horticulture and suburban living. More on Instagram @AbsenteeGardener or email info@absentee-gardener.com.

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