See this NYT article: Sorry, Vegans: Brussels Sprouts Like to Live, Too

But before we cede the entire moral penthouse to “committed vegetarians” and “strong ethical vegans,” we might consider that plants no more aspire to being stir-fried in a wok than a hog aspires to being peppercorn-studded in my Christmas clay pot. This is not meant as a trite argument or a chuckled aside. Plants are lively and seek to keep it that way. The more that scientists learn about the complexity of plants — their keen sensitivity to the environment, the speed with which they react to changes in the environment, and the extraordinary number of tricks that plants will rally to fight off attackers and solicit help from afar — the more impressed researchers become, and the less easily we can dismiss plants as so much fiberfill backdrop, passive sunlight collectors on which deer, antelope and vegans can conveniently graze.

Those claims are supported by a number of examples of the liveliness of plants that are interesting and valuable in their own right even if you are unmoved by the underlying logic of the argument. I've cited many research articles that noted the sophisticated "awareness" of plants though it isn't of the animal sort. For example, plants compete with their siblings in a different way than with strangers, in fact, they cooperate. But they talk funny.

“Plants are not static or silly,” said Monika Hilker of the Institute of Biology at the Free University of Berlin. “They respond to tactile cues, they recognize different wavelengths of light, they listen to chemical signals, they can even talk” through chemical signals. Touch, sight, hearing, speech. “These are sensory modalities and abilities we normally think of as only being in animals,” Dr. Hilker said. . .

Just because we humans can’t hear them doesn’t mean plants don’t howl. Some of the compounds that plants generate in response to insect mastication — their feedback, you might say — are volatile chemicals that serve as cries for help. Such airborne alarm calls have been shown to attract both large predatory insects like dragon flies, which delight in caterpillar meat, and tiny parasitic insects, which can infect a caterpillar and destroy it from within.

Enemies of the plant’s enemies are not the only ones to tune into the emergency broadcast. “Some of these cues, some of these volatiles that are released when a focal plant is damaged,” said Richard Karban of the University of California, Davis, “cause other plants of the same species, or even of another species, to likewise become more resistant to herbivores.”

Bottom line:

It’s a small daily tragedy that we animals must kill to stay alive. Plants are the ethical autotrophs here, the ones that wrest their meals from the sun.

A comment on the article accepts the facts but reasons thus:

Jainism, an Indian religion, advocates ahimsa or non-violence to all things but recognizes that violence is necessary to live. All we can do is to minimize our violence. Jains believe that the more senses a living thing has, the more pain it experiences and the more violence we cause when we kill it. So, to minimize violence, they say, to live, kill those things that have the fewest senses. ie. Kill the potato, but spare the pig.

I find both of these views to be narrow minded and naive. It's not a tragedy that all things kill to live, including plants who are not just "ethical autotrophs" since they will kill indiscriminately to assist in their own survival and that of their progeny. And it is simply ignorant to claim that the number of senses that a living thing has is in some way related to pain or superior experience. As we gain more scientific knowledge we become aware of senses that plants possess that the ancient religious thinkers simply didn't notice, and are at least beginning to back off from crude "speciesism" a bit to recognize that all we had been doing was claiming that beings that were more like ourselves were more alive in some sense. It was arrogant, provincial nonsense.

IMV the ethical stance is to recognize the condition of life, that all living things exist due to the deaths of others. If you think this tragic then you have some maturing to do. It is also beautiful, even awe inspiring, a marvelously complex system for achieving local violations of entropy, a madly courageous stance against an implacably violent and indifferent universe.

The practical stance is to maximize life. Killing is part of that. Death is unavoidable. But there are things that you can do to increase the amount of living things at a given time. If it is life that you venerate then this may make sense to you. Increase life.