August 21, 2012
Our Library Volunteer and great recreational reader, Pam Wolken, recently read two plant-themed books and has kindly shared her experiences with you. Hopefully, after reading her reviews, you'll want to take the journey yourself. Both books are available through the Arboretum Library.
What a Plant Knows; A Field Guide to the Senses by Daniel Chamovitz (2012)
On a tour of Costa Rica, the naturalist-guide pointed out an avocado tree, explaining that it produced meaty fruit with small pits early in the season to attract birds and animals to it. It would become their preferred tree and, like loyal shoppers everywhere, they would return to it. Later in the season, the trees' fruit showed much bigger pits which had better success of growing wherever the critters dropped them. This begs the question of how and what the tree “understands” (or “cares”) about reproductive success.
In “What a Plant Knows; A Field Guide to the Senses,” Daniel Chamovitz addresses the very issue of plant “behavior” beginning with the lack of plant-based vocabulary to explain stimulus response. Describing the symptoms is easier: plants bend toward light and other factors. Looking at the how and why and DNA of plants is at the core of this delightfully readable account.
Chamovitz spares no science in delving into plant senses of sight, smell, touch (feelings of being touched, actually), hearing, location awareness and some memory sense. Without recognizable sensing organs, plants still possess analogs of an eye's rods and cones to react to colors as well as intensity of light.
Hearing is a bit more of a problem since decades of experimentation of playing music for plants has no clear evidence of a stimulus response, much less a preference by plants (although strong preferences among some observers). Harmonics at frequencies not detectable by humans may effect plant systems, however. Plants are shameless at using scent to attract pollinators, and at the same time have been found to emit and react to aroma-causing molecules as warning of harm such as an injury or infestation. One of the best-known is using ethylene to stimulate ripening, which a tree will do in its own, as a fruit ripens it emits ethylene to signal its brethren to all ripen together.
The “shy virgin” plant will curl when touched, and many others will in various ways record an experience of being touched and use it in future situations. As for awareness of location, since plants are rooted in place with limited options for location changes, they do possess analogs of a human inner ear's otoliths to sense up from down – gravity detectors. The trendy up-side-down plants simply react as they are suppose to and the roots grow “down” within the vessel while the emerging shoots eventually turn upwards.
But before the one ascribes plants with sentience or tries to define a vegetal intelligence, Chamovitz is quick to point out that as far as has been determined plants have no emotional values assigned to what they perceive: a plant will react to having a leaf stabbed or root amputated, but not by saying “ouch.” Plants are much more neuro-sophisticated than they have been given credit for in the past, and yet seem to form no recognizable emotional bonds with each other as individuals.
This is a “must read.”
The Brother Gardeners by Andrea Wulf (2008)
Tulip mania in the Netherlands notwithstanding, the British maintain a national identity as world-renowned plant and garden lovers. Exploration and settlement of the western hemisphere, along with trade with the Pacific rim of Asia and Australia was a brand new candy store opening on Christmas for English botanists. Andrea Wulf explores “The Brother Gardeners” beginning with the work of Thomas Fairchild. In 1716, Fairchild used a feather to cross-pollinate a sweet william with a carnation, thus demonstrating that plants reproduce sexually like animals. The act of intervention had Fairchild living “in fear of God's wrath for the rest of his life” and explaining the resulting hybrid as a natural accident.
With the stage set to adapt plants from all over the world to live in Britain outside of hothouses, Peter Colinson, a London cloth merchant and avid botany fan, established a plant trade relationship with farmer John Bartram near Philadelphia. Theirs was a lively exchange for many years. Then Philip Miller published the Gardeners Dictionary and the democratization of botany, horticulture and gardening was launched. Buyers, sellers, suppliers and propagators could share a common vocabulary describing plants. This lively romp through the eighteenth century world of plants was revolutionized by Carl Linnaeus who furthered the sexual identities of plants with a system of naming conventions to categorize plants unambiguously. The stage was set for Joseph Banks, Daniel Solander and others to bring plants from around the world to Britain, and offer them back again for gardens royal and common. The images of plants in their native habitats reformed garden styles from the stiff organizations known in Europe to a more flowing, natural appearance.
Gardening became a passion in reach of all: democratized, homogenized, and practicable in most homes. Of all the books in all the world to read in a finite lifetime, this one is worth reading twice.