In Praise of Plants, by Francis Hallé, is a pop science book (i.e. scientifically informed, but aimed at a general, non-specialist audience) about the biology of plants. The author, a French botanist whose speciality is trees of the tropics, writes explicitly to correct the zoocentrism of mainstream biology: its tendency to take primarily animal models, and to generalize what is true of animals into what is true of biological organisms generally. Hallé argues that this not only does an injustice to plants and other organisms — one rooted in the narcissism and navel-gazing of human beings as a species, since of course we are animals ourselves — but also gives a constricted and distorted view of life’s potentialities.
To a certain extent, In Praise of Plants could be described as an old-fashioned work of “natural history.” This is the sort of biological writing that preceded all the last half-century’s discoveries about DNA and the genome. Such writing is anecdotal, empirical, and broadly comparative; it emphasizes historical contingency, and it pays a lot of attention to morphology, embryology, and other such fields that have been largely ignored in the wake of the genetic revolution. I myself value natural history writing highly, precisely because it presents an alternative to the genetic reductionism, hyper-adaptationism, and use of mathematical formalization that have become so hegemonic in mainstream biology.
Hallé emphasizes precisely those aspects of plant life that are irreducible alike to animal paradigms, and to the hardcore neo-Darwinian synthesis. Plants’ immobility, and their ability to photosynthesize, are the two things that differentiate them most radically from animals, which are usually mobile and unavoidably predatory. But these differences lead to many astonishing consequences. For instance, plants’ inability to move is probably what has led to their astonishing biochemistry: since they cannot defend themselves by running away, they have evolved all sorts of complex compounds that affect animal behavior (from poisons to psychedelics to aphrodisiacs). For similar reasons, plants don’t have fixed “body plans” the way most phyla of animals (like vertebrates or arthropods) do. Instead, plants have far fewer organs than animals, and these organs can be (re)arranged more freely; this allows for a far greater diversity of shapes and sizes among even closely related plant species than would be possible for animals.
More importantly, reproduction is much more fluid and flexible among plants than it is among animals. Plants can — and do — reproduce both sexually and asexually. They are able to hybridize (with fertile offspring) to a far greater extent than animals can. They have separate haploid and diploid life stages, which greatly extends their options for dispersion and recombination. Where mortality is the compulsory fate of animals, most plants (all except for the “annuals”) are potentially immortal: they can continue to grow, and send out fresh shoots, indefinitely. This is (at least in part) because plants do not display the rigid separation between germ and soma that animals do. Acquired characteristics in animals cannot be inherited, because only mutations to the gametes are passed on; mutations to the other 99.999% of the animal’s body play no part in heredity. But since plants do not have the germ/soma distinction, and since all the cells of a plant remain potentially capable of producing fresh shoots and of flowering, plants can accumulate mutations both in themselves and in their offspring (they can exhibit Lamarckian as well as Darwinian inheritance). They are also far more capable than animals are of receiving lateral mutations (i.e. when a mutation is spread, not by inheritance, but by transversal communication, via a plasmid or virus that moves from one species to another, taking genetic material from one organism and inserting it into another). For plants, natural selection therefore takes place less between competing organisms than among the different parts of a single organism; large trees will often contain branches that have different genotypes.
All this is quite mindblowing, and suggests a far broader picture of life than the one derived from zoology alone. The only scientist I can compare Hallé to in this regard is Lynn Margulis, whose now accepted theories about symbiosis, together with her still unorthodox theories about the mechanisms of evolution and speciation, derive to a great extent from her focus on bacteria and monocellular eukaryotes instead of animals. Hallé doesn’t have Margulis’ theoretical breadth, but his presentation has equally subversive implications vis-a-vis the neo-Darwininan orthodoxy.
One consequence, for me, of In Praise of Plants is that Deleuze and Guattari’s distinction between “rhizomatic” and “arborescent” modes of organization needs to be rethought. In point of fact, trees are far less binaristic and hierarchical than Deleuze and Guattari make them out to be. D&G are really describing both the rhizome and the tree in largely zoocentric terms. A better understanding of botany would actually fit in quite well with D&G’s larger philosophical aims. (Deleuze does show a somewhat better understanding of botany in his treatment of the sexuality of flowers in his book on Proust).
The main (and only substantial) flaw in In Praise of Plants is that, in his desire to emphasize the difference between plants and animals, Hallé gives short shrift to the third kingdom of multicellular organisms, the fungi. He basically spends just a single paragraph on them, in the course of which he presents them as intermediate between plants and animals. This means that he sidelines and belittles fungi in precisely the same way that he (rightly) accuses mainstream biologists of sidelining and belittling plants. Since Hallé is a botanist and not a mycologist, I wouldn’t expect him to give a full account of the fungi. But he ought at least to acknowledge that such an account is needed, since fungi are arguably as different from both animals and plants as the latter are from each other. This would certainly seem to be the case from the tantalizingly little I know about the sexuality of fungi. Where will I find a book that does for the fungi what Hallé’s book so magnificently does for the plants?