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or a fine wine, their message to humans can be attractive. But plants do not expend valuable energy making these chemicals simply to please humans, and most volatiles have more serious functions. Some, for instance, are important in communicating information to particular insects that is crucial to the survival of the plants, and often the insects as wellâ¦At night, tobacco plants that are being attacked by caterpillars emit a specific blend of volatile chemicals. Nocturnal moths interpret these chemicals as a signal that they will not be welcome to lay their eggs there. But it isnât just the plant that benefits from these night-time emissions. As the plant is making nasty chemicals to ward off the caterpillars, and may be summoning help from predatory insects, it is advantageous for the moths to keep awayâ(p. 530). See Trewavas (2002) for the article quoted in the first paragraph of the main text.

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P. 85: STENHOUSEâS DEFINITION OF INTELLIGENCE

See Stenhouse (1974, p. 31).

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P. 86: STILT PALMS AND GROUND IVY

Trewavas (2003) writes: âThe stilt palm is constructed from a stem raised on prop roots. When competitive neighbors approach, avoidance action is taken by moving the whole plant back into full sunlight. Such obvious âwalkingâ is accomplished by growing new prop roots in the direction of the movement while those behind die off. That this is intentional behavior is very clearâ (p. 15). Phillips (2002) writes: âRoots can follow mineral or moisture gradients in the soil, but they donât always take the simple route. Hutchings and his colleagues have studied the foraging behavior of a creeping herb called Glechoma (ground ivy). When theyâre in good soil these herbs grow more branches, shoots and leaves. They also form clumps of root much faster to fully exploit the patch. But when theyâre on poorer territory they spread farther and faster, almost as if theyâre escaping, and their rhizomes are generally thinner and branch less frequently. This means that new shoots develop further from the parent plant and actively search for new resource-rich patches. And the amount of growth is not related just to the absolute quality of a patch, but to how good it is relative to surrounding soils. Not only that, but experiments have shown that related plants can sense the presence of competitorsâ roots and head off to other areasâeven when thereâs still lots of food aroundâ (p. 41). And Wijesinghe and Hutchings (1999) write: âIn conclusion, this study revealed a close match between resource availability and the placement of resource-acquiring structures under all but the most heterogeneous conditions, and greater morphological specialization when resources were distributed in large patches with high contrast in quality. Glechoma hederacea clearly has an acute perception of the quality of its environment, and responds to it through foraging and local morphological specializationsâ (p. 871).

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P. 87: PLANTS FACE A WIDE VARIETY OF ENVIRONMENTS

Trewavas (1999a) writes: âWhat particular problems faced by plants require intelligent behavior? Wild seedlings must grow where they land. The external environment is composed of probably 17 distinct constituents and, being variable in intensity even from minute to minute, generates an almost infinite variety of environmental states. There are probably as many internal plant signals that either pass through or are perceived at the plasma membrane. In responding intelligently to this multiplicity of signals, plants have become masters of phenotypic and physiological plasticity, which allows them to cope with the variable circumstances that surround them. Behavioral plasticity surely demands a cellular system of considerable computing power if plants are to survive the signal morass in which they find themselves. The ubiquity of calcium involvement in plant-cell signal transduction suggests that calcium forms the basis of the intelligent system controlling plasticityâ (p. 5).

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P. 88: DODDER MAKES INTELLIGENT DECISIONS

According to Kelly (1992), who did the original research demonstrating active