“As interesting as watching grass grow” is a cliché. It is also indicative of the ignorance that most people have of the fascinating world of plants.
Granted, it is not very interesting to watch plants grow in real time. But if their growth is compressed into the time span of human perception, as in the superlative films of Sir David Attenborough, or if you measure their growth over time, you can discover some very interesting things about them. While plants do not have intelligence, they adjust their growth to their environments in ways that look intelligent to us. Plants have to make a living, like everyone else, and their growth patterns allow them to do this. As a seedling grows, its stem may actually do a little circular dance (circumnutation) in search of light. As its leaves expand, their anatomical structure adjusts to the amount of light: thinner leaves with more chlorophyll in shade, thicker leaves with less chlorophyll in bright sun. Meanwhile the roots penetrate the soil and proliferate their growth in patches that are rich in nutrients. Plants have a limited amount of food stored in their cells, and they invest this food in growth that is appropriate to their conditions: they invest more in roots if the soil is dry, and more in leaves if the soil is moist. Plants also prepare for the future, producing next spring’s buds the previous autumn. When the leaves burst open from buds in the spring, you are seeing merely the expansion of tissues that were built the previous year.
Perhaps watching grass grow in real time is not very interesting, but to envision its growth over the course of days and weeks in the real and complex world can be astonishing.
Originally published on http://www.stanleyrice.com in March, 2008.