Did That Plant Just Move?
To our frame of time, plants are sessile organisms, that is, they don’t move.
As previously mentioned, there are very unusual plants such as the Venus flytrap and Mimosa pudica, that do move in response to mechanical stimuli in “real time”, that is, our frame of time.
But thanks to time-lapse photography – or if we are very patient and careful observers – we can perceive that most plants do indeed move, albeit very slowly.
And, of course, there is always YouTube. For example:
But long before there was time-lapse photography, people were aware of, and often fascinated by, plant movements. And, especially in the 19th century, such plant movements became the subject of methodical scientific inquiry. Particularly by someone more well-known for his theory of evolution.
Darwinian Plant Movement
As mentioned in a previous post, in 1880 Charles Darwin and son Francis published a book called The Power of Movement in Plants. (A facsimile of the original book can be downloaded here – beware – 316MB PDF file).
In this book, the Darwins report observations of a wide range and variety of movements in plants. In their own words: “The chief object of the present work is to describe and connect together large classes of movement, common to almost all plants. The most widely prevalent movement is essentially of the same nature as that of the stem of a climbing plant, which bends successively to all points of the compass, so that the tip revolves.” (See the YouTube video above for examples.)
The Darwins named this movement “circumnutation“, which is defined by the Oxford English Dictionary as: ” A movement characteristic of growing plants, due to increased growth at different points round the axis in succession, whereby the growing part (e.g. the apex of a stem) describes a more or less circular spiral path.”
Fast-forward 130 years, and we have a delightful new book on the same subject.
The Restless Plant is by the late Dov Koller, who was Professor Emeritus in the Department of Botany at the Hebrew University of Jerusalem.
From Koller’s Preface to the book: “The Restless Plant is my comprehensive, up-to-date account of the incessant movements in all actively growing plants. Developments and advances in this area of plant sciences since the 1880 publication of Darwin’s The Power of Movement in Plants have been tremendous. This is not a textbook, nor is it a scientific review. It is intended for the general, educated lay public of all scientific and nonscientific disciplines as well as for that part of the general public who might be interested in the endless variety and fascinating phenomena of plant movements, and in what is known about what makes them happen.“
Unfortunately, Professor Koller died before completing this book, but, fortunately, Professor Liz Van Volkenburgh agreed to take on the partially completed manuscript and finish the job.