Ranger Steve Mueller
By Ranger Steve Mueller
Shining silver that does not tarnish glistens at the tips of wild strawberry leaves early in the morning. Instead of tarnishing, the silver evaporates in the morning warming sun. Humidity in the air determines how long silver beads will persist.
Guttation is responsible for water drops developing in rows along leaf edges and tips. At strawberry leaf tooth tips are microscopic spongy cells surrounding a tiny pore that allows water to ooze from the leaf. Water is drawn into plant roots like corn, grasses, and many other plants by uneven water pressure between high soil moisture and low moisture within the plant.
When soil is dry, water does not enter the plant. Avoiding dehydration is essential and all plants have adaptations in their nature niche to help them survive. In the Great Lakes region, it seems we have plenty of moisture but even within sight of the Great Lakes, some plants live in an arid environment.
The sand dunes have large coarse sand particles where water flows through rapidly. Without drought resistant adaptations, dune species would not survive. Plants living in constantly wet soils or in shallow standing water would drown without special adaptations for such conditions.
To some degree plants regulate water flow through their bodies. Leaves have massive numbers of tiny pores on the surface called stomata. Surrounding each pore are two bean shaped guard cells. When the plant is full of water, the guard cells swell. The inner side of each guard cell by the pore has a thick inflexible wall and the outer side has a thin wall that bulges when the cell fills with water. The more inflexible side arches to make the pore opening bigger as the outer side bulge increases outward.
The tips of the two bean-shaped cells touch but the opening between the two cells enlarges allowing water to escape to the air. When water evaporates from the surface, it tugs on water molecules and pulls more up through the root, stem, and leaves. It helps transport nutrients for plant tissues. The plant controls water content by opening and closing stomata based on moisture in the guard cells.
Guttation is different and is not regulated. The pore at the leaf edge is always open but these pores are limited in number. During the night when water vapor is high in the atmosphere (high humidity), evaporation is reduced. Large drops form and grow to form the silver beads we see in the morning.
During the Memorial Day weekend, it was a great pleasure to venture in the naturalness of Ody Brook to see any and all special things. Hopefully everyone spent time outdoors between infrequent rain showers. Much of the weekend was rain free but both ground and air humidity were high. As water was drawn into roots by uneven water pressure, it accumulated on leaf tips as it leaked from the always open pores. The result was beautiful silver water beads shining in the early day’s sun along leaf edges.
For eons this natural process occurred before our presence. It moves valuable nutrients like potassium and nitrogen through the plant. If we add too much nitrogen to the soil, fertilizer burn can occur. During the past 20 years’ a new danger to life has been added. Neonicotinoid insecticides have been added and become concentrated in guttation water beads. When bees drink guttation water from plants grown from neonic treated seeds, they can die within minutes. It is increasingly difficult for farmers to purchase seeds that have not been treated. Neonics are thought to be a cause of bee colony collapse disorder. Research continues but scientific confirmation takes time and repeated verification.
We can enjoy the natural wonders in our yards but we should learn to live in harmony with the lives of bees and other insects that make our lives possible by their daily work in gardens and farm fields.
Natural history questions or topic suggestions can be directed to Ranger Steve (Mueller) at odybrook@chartermi.net – Ody Brook Nature Sanctuary, 13010 Northland Dr. Cedar Springs, MI 49319 or call 616-696-1753.
