Secret life of seeds

As I watch spring transition into early summer, my thoughts turn toward seeds. Even though new flowers continue to bloom, early spring blossoms are now wilted and dried, leaving only their seeds as evidence of life. The wild cucumber's spike balls peel open to drop their potential. Likewise, the lupine pods dry out and curl apart to release their pealike seeds.

While this is a natural cycle- birth, growth and death- I am most interested in the timing of the seeds and their blossoms. While some annual plants have already undergone their entire life's cycle for the year, others are just beginning to sprout and bloom. Seeds that found their home in the soil last spring are only now choosing to emerge.

I wonder about this timing. What is it that triggers a seed to begin its rumblings and start germination? What force transforms the seed's enormous potential energy into kinetic energy?

It's all in the timing

Upon pondering and researching this further, I come upon an essential concept in the world of seeds: Dormancy. When I think of dormancy I think of a coil loaded, ready to spring. I think of an inert body waiting until the time is right to come forward. I think of my own ideas and dreams that lie still until they surface at the exact moment that I am able to support them and carry them through.

And fundamentally this is exactly what dormancy is for a seed. The ability to lie dormant for extended periods allows the seed to wait until conditions are ideal for germination and the growth of the seedling.

The evolutionary shift of plants from water to land would have been nearly impossible if not for the vast adaptations of seeds. Watery habitats are much more stable in respect to terrestrial habitats, which are at the mercy of drastic weather conditions. Living on land exposes plants to significant temperature changes within hours, as well as drought, flooding, fire and frost. In order to survive these circumstances into the next generation, seeds evolved the ability to lay dormant for anywhere from a few days to hundreds of years.

Although many people believe that germination, or sprouting, is the beginning of a plant's life, the seed, even in dormancy, is a complete life containing a miniature plant inside. Within a seed can be seen an embryonic root and shoot. Therefore, dormancy is a part of the plant's life cycle, just as hibernation is for an animal, rather than an end. A dormant seed is the loaded spring ready and waiting for ideal conditions.

What are the ideal conditions?

Waiting in the wings

As with each person's ideas and dreams, the "ideal" conditions vary depending on the species of seed. While a desert seed may break dormancy after a slight drizzle, plants I observed in the Central American rainforests needed to be immersed in water for days before germinating. Other seeds need the shock of a freeze to stimulate their growth, such as many fruit trees of the Northeast. In addition to temperature and water, light may be a cue to which seeds respond. For instance, the very small seeds of lettuces will only break dormancy if they are buried shallowly enough for light to penetrate the soil and reach the seeds.

Another mechanism to wake seeds from the dormant state may be attained with the help of animals. Some seeds' coats are only broken after they have passed through the chemicals within a creature's digestive tract.

A mechanism exceedingly favorable to chaparral plants is germination via fire. There are more than 200 species of annual herbaceous plants and shrubs that will lay dormant for decades until they detect the passage of fire. These pyrophyte endemics are unique to the chaparral and require the exposed soil conditions that occur when mature shrubs are cleared away by fire. Many of these pyrophytes have detection systems that sense this situation, responding to chemicals produced

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