Recently, I was harvesting vegetables with some volunteers, and we happened to be training cucumber to climb some supports. I began to explain some of the adaptations plants use to reach for the sun.
The simplest method of climbing is simply growing upward and wrapping the stem around an object. Plants such as morning glories are known as “twiners”, oddly enough.
Another group of plant rely on super sensitive plant parts called tendrils for climbing. Tendrils can be modified leaves, leaf tips, leaf stalks, or branches which twine around, grasping the object, aiding in pulling the plant upward. I find this adaptation particularly cool. The tendril will wave about blindly, seeking something to grasp. As soon as it senses an object, it causes the cells to elongate through the use of plant hormones on the opposite side of the stem from the object, thus bending the stem toward the object. Cucurbits (plants in the gourd family Cucurbitaceae) such as cucumbers and squashes go further. Once cucurbita tendrils begin to wrap around a plant support, another coiling motion begins like a corkscrew, pulling up any slack in the tendril, drawing the plant closer to the support.
Some other cool methods include modified flowers, leaves or thorns as hooks, or modified roots like the english ivy. Get outside and see how your plants are on the up and up.
Josh Steffen, Horticulture and Facilities Manager