Learn More About botany. Time Traveler for botany The first known use of botany was in See more words from the same year. Style: MLA. English Language Learners Definition of botany. Kids Definition of botany. Medical Definition of botany.
Get Word of the Day daily email! Test Your Vocabulary. Test your visual vocabulary with our question challenge! Love words? Need even more definitions? The group of plants or animals must have one and only one name. Ideally, the name should be a stable ID for all occasions. Throughout the long history of taxonomy, too many names were given to the same taxa. At the moment, we have almost 20,, names to describe 2,, species.
To regulate the use of names, nomenclature codes were created. These codes specify, for example, the rule of priority : when two names are given for the same group, only earlier name is valid. Another important concept of nomenclature is the nomenclature type. Practically, this means that every species name must be associated with the physical museum specimen.
In botany, these museums are collections of dried and pressed plants, called herbaria. Names of taxa higher than species also have nomenclature types, but in these cases they are other names, not specimens. This example may clarify the use on nomenclature types. Thomas Nuttall decided to split sea-buckthorns in two genera. The second genus can be named arbitrarily.
Plant taxonomy is a science. That means that our understanding of plant groups will always change. It also means that there always are different competing opinions, the taxonomic hypotheses which describe plant diversity in different ways.
As a result, some groups of plants could be accepted in a broad sense, including as many subgroups as possible. For example, there might be an opinion of Homo sapiens s.
A computational network can form slowly or quickly, but sugars, amino acids and fatty acids will be some of the information transmitted between individual aleurone cells Trewavas, Pericycle cells more sensitive to auxin or other factors will act as foci for the formation of branch roots. The different sensitivities of individual pericycle cells act to provide a broad range of lateral root production in different root environments.
Using a microbeam of red light, Nick et al. They reported patchy formation of the pigment and indicated that there was substantial variation in the sensitivity of individual cells. Communication is clearly happening, but the mechanism of communication has not been established. But again, anthocyanin formation can be optimized to fit the environmental requirements and to improve overall fitness.
The benefits of individuality are to be found in the much greater variety of response provided to the individual plant. Williams provided an interesting way of assessing the variation in populations Box 1.
Williams approached biochemical individuality in an interesting way. He examined whether it was possible for a single uniform drug dose to be prescribed for the whole human population, and concluded it could not be.
Ergo, we are all deviant in certain characteristics. There are at least 15 distinguishable environmental signals [water, five or six primary minerals, light, gravity, soil structure, neighbour competition, herbivory, disease, allelopathy, wind, gases; Trewavas, ] to which individual plants are sensitive, many observable traits that can be distinguished, and there may be as many as the number of distinguishable genes.
On that basis, it is likely that every individual plant, at least in the wild, is unique in one or more traits. Williams also describes anatomical and biochemical individuality in normal reproducing human beings, and lists the variations that he could find in the literature for apparently normal healthy, reproducing, human beings.
The variations described are enormous given the necessity for producing such a complex organism. It would be useful if an equivalent catalogue of plant variation could be compiled, if that is possible. However, the modular character to plant growth and development and plasticity might make this a difficult task. But the biochemical observations measuring variations in vital constituents could equally apply to plants, although I have never seen them compiled.
No doubt, metabolite profiling will indicate this in greater detail. The Handbook of biological data does contain some information about plants, showing variation in dry weights, protein, secondary metabolites, ions and other metabolites. Elsasser regarded the data compiled by Williams to represent the primary difficulty in the instructionist view of life that regards the genome as merely a computer tape full of information and the cell as a computer following instructions that should then always result in exact replicas clones of the genome.
Thus organisms survive perfectly well despite huge variations in constituents, and the notion of being simply complex machines which require precision and reproducibility in structure and composition is untenable. Plasticity is the degree to which an organism can be changed in response to environmental signals and is, as indicated earlier, a clear example of plant intelligence.
Plasticity can be expressed in both physiology and morphology. Guard cell plasticity or, more exactly, plasticity in transpiration is clearly physiological plasticity. Other physiological examples are to be found in carbon assimilation photosynthesis rates and dry matter partitioning Bloom et al.
Karban and Baldwin indicate that herbivory and pest defence mechanisms can generate enormous numbers of physiologically distinguishable individuals arising from the moving target model.
This model suggests that pest attack results in effectively random resistance responses in identical tissues such as leaves. Indeed, data provided by these authors indicate that on a single tree every leaf was observed to be at a different stage of pest resistance. Morphological or phenotypic plasticity has been studied for many years, largely by population geneticists because of its relevance to evolutionary studies see Box 2.
Phenotypic plasticity generated by environmental variation is commonly expressed in growth habit and size, morphology and anatomy of vegetative and reproductive structures, in absolute and relative biomass accumulation, growth rates, functional cleistogamy, variable sex expression and offspring developmental patterns Bradshaw, ; Diggle, ; Bazzaz, ; Pigliucci, ; Schlichting and Pigliucci, ; Ackerley et al. Variations are also common in stomatal frequency, hairiness of leaves, palisade vs.
Even the number of petals on a flower can change after leaf removal Tooke and Battey, Maryland Mammoth tobacco Taiz and Zeiger, , and the ability of gardeners to grow outsize giant vegetables indicate the extent to which variation is possible if the right growth conditions are provided.
For example, the record pumpkin is kg Guinness Book of Records, How giant fruits and vegetables can be grown without the apparent selection of particular genotypes in the first place is indicative of the extent to which epigenetic phenomena must contribute to the final phenotype.
It is generally accepted that genotype determines whether the individual phenotype or character can be plastic in the first place; expression and extent of that plasticity is environmentally regulated. Phenotypic plasticity has long been investigated by those interested in evolutionary studies. Certainly around the turn of the 20th century, Darwinian views were opposed by some botanists because of phenotypic plasticity.
Henslow provides a number of examples, such as two kinds of Ampelopsis , one of which forms suckers on mechanical stimulation, the other which forms them regardless of stimulation. Henslow supported Lamarckian views to explain these data, but genetic assimilation is a much more likely hypothesis.
That is, the original character is the result of temporary adaptation, and natural selection increases the numbers of individuals more able to optimize the character before finally simple mutations ensure the character becomes fixed.
Suggestions that genetic assimilation is a major mechanism in evolution have recurred from time to time. Baldwin called this organic selection, and may have been the first to suggest the possibility. It might be thought that these would be an adaptive feature, but they are clearly visible on the embryo inside the egg, supporting genetic assimilation mechanisms. The important feature in genetic assimilation is the persistence of the environmental situation, so that the novel, initially adaptive behaviour persists.
With time, genes and gene combinations originate that allow the strategy to develop with greater rapidity, higher probability or lower cost Bateson, Eventually mutations appear that fix the trait regardless of environmental signalling. Thus, in these cases, natural selection merely ratifies an adaptation that has already been developed and tested. The molecular origin of genetic assimilation must occur in signal transduction processes.
Further discussion of this important aspect of phenotypic plasticity can be found in Bradshaw ; Bradshaw and Hardwick ; Bazzaz ; Schlichting and Pigliucci ; Sultan , and references therein. The timing of many developmental processes is certainly subject to plastic modification Bradford and Trewavas, Even environmental influences on the parent can be detected in the resulting seedlings, certainly to one or more generations Mazer and Gorchov, and in certain cases much longer Durrant, Plasticity is adaptive; this has recently been made clear Ackerley et al.
Phenotypic plasticity is a visible witness to the complex computational capability plants can bring to bear to finely scrutinize the local environment and act upon it. However, plasticity can be limited to certain characteristics in plant development, with others remaining stable.
But pinnate leaf shape, leaf margin serration, shape of the inflorescence and floral characters remained stable within limits, at least under the conditions investigated. The presence of morphological plasticity for specific traits is genotype dependent e.
Sultan and Bazzaz, a , b , c and thus individual in character as required by the definition of plant intelligence. But many life history characters, such as mortality, growth rate and fecundity—important components of fitness—are more dependent on the environment than the genotype Antonovics and Primack, Thus, the perception of the genotype is changing from a blueprint that describes a single fixed outcome to a constrained repertoire of environmentally contingent and intelligent processes.
The phenotype is ultimately constructed from synergistic developmental systems in which genes and gene products interact in a complex fashion with signal transduction networks, in turn directly responsive to numerous and constantly changing environmental factors Trewavas and Mahlo, Phenotypic plasticity enables individuals or genotypes to assume obviously different phenotypes during the life cycle Schlichting, ; Sultan, Moreover, given the variety of environmental parameters and the different orders and combinations in which they occur in the wild, the potential number of distinguishable phenotypes must be enormous.
Phenotypic variation can even cause substantial problems in taxonomic classification. Just as animal behaviour is constrained by genetic capabilities, so ultimate genetic constraints on phenotypic change will be present. But with plants refining their discrimination to local conditions, perhaps the enormous numbers of distinguishable phenotypes corresponds well with the number of behavioural variations available to any animal. But plasticity indicates foresight.
For plants that experience, for example, either periods of water stress or shading, morphological adaptations in the leaves improve fitness but at a cost that would not be experienced by other individuals that received adequate water or light.
It is here that the capacity for intelligent behaviour must be paramount. Just as any animal will assess the totality of its sensory environment and respond, a plant will carry out the same assessment of all conditions and adjust its growth and development from that assessment.
Furthermore, faced with new patterns of environmental variation, plasticity enables the individual to come up with some sort of solution first time. Those individuals that have the best behavioural solution will survive better and go on to reproduce. Further improvement by selection can be expected if the new environment remains. Repetitive and reproducible changes in the environment easily lead in turn to genetically proscribed behaviour by natural selection if the new environmental constraint is permanent.
Phenotypic plasticity is much more readily obvious in plants than in animals. Development continues throughout the plant life cycle and is thus subject to environmental influences to a greater extent.
Theoretically, every plant body contains its environmental history, if that could be read. In mammalian brains, phenotypic plasticity underpins the process of learning and memory.
Except in early development, neural cell numbers do not increase, and changes in function are provided, as already described, by changes in either number of dendrite connections or synaptic adhesion that form the adaptive neural networks essential for intelligent behaviour.
It is the ability to create new computational networks that either direct the flow of information into different channels or reference previously held memories that are crucial. Once new dendrites form or decay the neural cell becomes effectively a cell with different functions. What is suggested here is: 1 the basic elements of computation are individual cells in tissues; 2 that computational cellular networks are formed as the tissue develops, best fitted for the environmental state of the time; and 3 each individual plant genet accumulates tissues ramets with different computational capabilities, so reflecting the history of experience.
Just as the process of learning in a brain could be represented as a time series, a set of snapshots of developing brain connections, in plants, each snapshot may possibly be represented by developing plasmodesmatal connections or equally, successive new tissues. So, instead of changing dendrite connections, plants form new networks by creating new tissues, a series of developing brains as it were, that can act like parallel processors each with slightly different computational capabilities.
In this way, the successive plant tissues act as repositories of memory of environmental states which, if such information can be conveyed elsewhere, contribute to the whole plant assessment. Evidence for this view is very limited, but plants do abscind their leaves as conditions change and can form new and obviously different leaves in the new conditions Addicott, It is also known that as leaves age, stomatal function weakens, thus there are leaves with varying potential on any one individual plant Willmer and Fricker, But how do different tissues arise from the same growing meristem, or are apical meristems identical throughout their life?
Progressive changes in successive leaves are known to occur in certain plants under constant conditions of growth Steeves and Sussex, , and bud dormancy can vary according to the age and position of the bud Gregory and Veale, Rooting of branches from some trees e.
In others, such as Hevea , cuttings only form adventitious roots and the main tap root is not regenerated. But to explain how phenotypic plasticity arises from what is often assumed to be an identical meristem, we can borrow from an idea by Edelman Neural territories and maps are often unique to each individual, for example.
He suggested that experience selected out certain groups of neurones by chance whose original connections constructed a weak response. These networks were then reinforced by increased synaptic adhesion with additional signalling. Channels of information flow were thus deepened, improving the quality of the response.
The suggestion here is that the true meristem produces cells that are anatomically indistinguishable but that differ in molecular and physiological capabilities. During development, as cells leave the true meristem, environmental conditions will result in the preponderant replication of certain cells with particular physiological patterns over others which, in due course, give rise to phenotypic plasticity; a kind of cloning Steeves and Sussex, Perhaps cells in the transition region between division and expansion are where selection occurs in roots Barlow and Baluska, In the apical meristem, larger leaves might originate as the environmental conditions select cells capable of expanding longer or to a larger final size.
Maybe these cells would differ in sensitivity to auxin or kinin. Examples of responses of very young tissues to ABA and cold treatment leading to different morphologies and tissues Spirodela turions are to be found in Smart and Trewavas Also, morphological data provided by Milthorpe indicate that young cucumber leaves of a certain age only respond to cold treatments. Intelligent behaviour is designed to maximize fitness but only in circumstances that challenge the survival of the organism and test its capability for intention within an evolutionarily determined end point and choice.
Ecological investigators are starting to construct circumstances in which intention and choice are tested. Foraging for food resources is an essential activity for both plants and animals. Consequently, most aspects of intelligent behaviour are exemplified in foraging for nutrients. Little is left to chance or plasticity in reproductive behaviour. For a similar reason, much plant taxonomy relies on flower structure in which plasticity is minimized.
For land plants, resources appear as a complex spatial and temporal mosaic Hutchings and deKroon, , in part reflecting patchy distribution of soil materials and neighbour competition Turkington and Harper, ; Salzman and Parker, Competition is certainly one environmental circumstance rarely provided in laboratory experiments. In a resource mosaic, intelligent behaviour is essential if resource collection is to be optimized in the face of competition.
Foraging is a term now used much more frequently in plant ecological literature and is a proper description of the way plants behave when gathering growth resources. Dodders Cuscuta sp. Responding to an initial touch stimulus, growing shoots take several days to coil around suitable hosts. Haustorial primordia and haustoria then differentiate and nutrient resources commence transfer from the host in about 4 d Kelly, In dodder, it is thus possible to dissociate active choice from the subsequent passive effects of acquired resources on growth that can complicate other situations.
Active choice was thus influenced by the anticipated reward. These data fit a simple marginal value model of resource use, applicable also to grazing animals; they also indicate plasticity in the length of coiling. Just as animals intelligently feed, so do plants. Seed set was correlated with the size of the parasite, indicating that host selection was adaptive and fitness of the parasite improved. It was suggested that rapid transfer of chemical information through the initial touch contact determined host selection and final length of coiling.
The uneven distribution of light to which wild plants are exposed is a critical factor controlling subsequent fitness. Light is critical to the acquisition of carbon resources and energy for other cellular processes. But many plants often called sun plants to distinguish them from shade plants do not react passively to the light mosaic in a canopy, simply accumulating dry weight when the light is strong enough.
The quality and quantity of light is actively perceived through red : far red ratios and the position of likely future competitive neighbours mapped Gilroy and Trewavas, Avoiding action is taken by accelerating the growth of the stem, which becomes thinner Ballare et al. Root growth is also altered, indicating communication of light perception to other parts of the organism Aphalo and Ballare, New leaves are then especially positioned free from competitive light interruption Ackerley and Bazzaz, The stilt palm Allen, is constructed from a stem raised on prop roots.
When competitive neighbours approach, avoidance action is taken by moving the whole plant back into full sunlight. That this is intentional behaviour is very clear. On reaching the top of a tree, the growing point descends, progressively changing its morphology and leaf structure, and eventually assuming a very thin filiform shape with only scale leaves on the soil.
Using skototropism movement towards darkness , the filiform stem explores, locates and recognizes a new trunk and reverses the growth pattern. As it climbs, the internode becomes progressively thicker and leaves progressively redevelop to full size Strong and Ray, ; Ray, , This behaviour is analogous to animals that climb trees to forage, intelligently descend when food is exhausted or competition severe, and then climb the next tree. Experiments with rhizomatous clonal herbs have shown that when provided with deliberate choice, the new growth of rhizomes and associated shoots is highly selective and is directed with much higher probability into favourable microhabitats.
The new territories that are exploited may consist of freedom from other competitors Evans and Cain, ; Kleijn and Van Groenendael, , unshaded and warmer temperatures MacDonald and Lieffers, , or weaker salinity Salzman, ; Salzman and Parker, When resources become abundant, dormant buds are induced to grow as shoots rather than new rhizomes Hutchings and de Kroon, Rhizomes that pen etrate the poorer environments are generally thinner, their internodes are longer and they grow more rapidly where possible.
Limited growth resources are thus efficiently used to cover maximum ground with minimum investment. Directing the majority of rhizomes to exploit rich resources whilst allowing others to search for new resources suggests optimal strategies are in place to maximize returns and increase fitness. When resources are scarce, growth materials are invested in the organ through which scarce resources are normally sequestered: if minerals or water are scarce, enhanced root growth occurs; if light is scarce, stem growth is enhanced at the expense of root growth.
But the growth of clonal herbs responds directly to the uneven distribution of resources in the soil. How the parameters of patch size and gradient strength lead to enhanced growth is not understood. It is difficult to avoid the conclusion of intention and intelligent choice and the ability to select conducive habitats in which to place and grow organs of resource exploitation.
Perhaps the most surprising observations come from Evans and Cain They tested whether the clonal herb Hydrocotyle , which grows on sand dunes, could preferentially locate good patches or avoid bad patches in a heterogenous environment. They reported that rhizomes veered away from patches of grass and thus obvious competition.
Intentional choice of habitat is clear. Individual roots can track humidity and mineral gradients in soil see summary of references in Takahashi and Scott, , just as shoots can track local light sources Trewavas, b. And, to avoid detrimental competition, roots like shoots take deliberate avoidance action to prevent contact when approached by roots of other species Mahall and Calloway, A major difficulty in studying any plant behaviour is that time scales differ from those in animals.
Whereas human beings operate in seconds, plants usually operate in weeks and months. Even though bamboos can grow a centimetre an hour, without some sort of recording device it would be extremely difficult for any human to observe this phenomenon. Plant behaviour in the wild is usually unrecorded and, as a consequence, much uncommon behaviour must simply be missed.
There is no doubt this is a serious omission in the scientific literature. There are so many crucial questions to pose. Why is it that one wild seedling survives and others do not, when apparently shed at the same time from the parent plant and in the same soil? There is so little information on the actual preliminary struggle for existence recorded in real time.
However, the particular combination that I have presented here of intelligence, learning, memory and fitness should place some facets in a different light. Their sessile life style is clearly successful and individuals must then possess a fine ability to adjust and optimally exploit the local environment.
How well they map the local environment and the extent of computation with good estimates of computational skill clearly still requires significant investigation in real not artificial environments. Much animal behaviour is strongly heritable for example, reproductive or early feeding behaviour is probably innate and, indeed, has to be.
So, in the same way, there are aspects of plant behaviour that are rarely phenotypically plastic. Apart from the fact that the major form of expression of animal intelligence is movement rather than growth and development, as defined here for plants, I find there is little to distinguish between the two groups of organisms once adjustments are made for the time differences noted above. As regards movement, the computer that beat Kasparov at chess surely an excellent example of intelligence in action regardless of the human requirement to program certainly required human intervention to move the pieces.
We have already described the necessity for the right environment to elicit intelligent behaviour, and the Kasparov chess computer is again an excellent example. Chess games were the right environment to elicit intelligent responses. In fact, chess provides a further and important illustration of how ignoring individual behaviour and simply averaging behaviour can confuse understanding.
Each chess game represents a unique and highly individual trajectory, recording intelligent behaviour between two properly matched opponents. Suppose instead that we now averaged chess games, much as physiologists average responses, and then looked for meaningful variations. The averaging process would reveal that pawns had a very high probability and a narrow standard error of being moved right at the beginning and the king being irreversibly confined mated at the end, although with greater variability.
Knights and bishops would have a high probability of being moved early on, although the probability mean would be lower than that for pawns and the standard deviation broader.
Castles rooks and queens would be later still and with much more spread in the standard deviation, and so on. In fact, averaging any one large set of chess games would look very similar to any other large averaged set, and we would conclude that the chess game on this basis was rote, started with a clock, of little interest and certainly nothing to do with intelligence.
And, in an attempt to understand what was going on, we might experimentally knock out pieces only to find that, yes they were necessary and you lose if they go, just as we currently knock out cells, chemicals, genes or signal transduction molecules in an attempt to understand what is going on.
Another crucial point is surely that very simple rules govern chess but the order in which events take place i. This may represent a paradigm for signal transduction. We are so used to thinking of intelligence as a property of the human individual that we fail to recognize the necessity of applying that rule to plants as well.
Perhaps a more critical question is: does it matter whether intelligence is used to describe plant behaviour? If intelligent behaviour is an accurate description of what plants are capable of, then why not use the term?
But, having used it, the next question is how it is accomplished in the absence of a brain. Whatever the mechanism, the end result usually comes from the distinctive behaviour of meristems. There must then be important conduits of proper information flow, as distinct from nutrients, from the rest of the plant into meristems. Hopefully this article can indicate more clearly the kinds of investigations needed to fill in the gaps. Undoubtedly, we need very much more information on cellular and tissue communication and the distribution of receptors for all those signals that have been uncovered recently.
We need many more studies on individual wild plant behaviour. How much information is conveyed between tissues, and what exactly is the sum total of its nature? Although the classic growth regulators are often assumed to carry out such communication, the uncertainty that still surrounds much of these notions is remarkable. Other answers will arise from creative construction of particular environments in which plants can demonstrate their undoubted behavioural potential.
Although we understand much more about signal transduction processes in plants than we did 20 years ago, there is a long road yet to travel, to jump the gap between cell, tissue and whole organism.
My hope is that, in future, this may become a more major highway. I would like to acknowledge the critical refereeing of the manuscript and positive suggestions by Professor J. Raven and Dr R. Their support in no way implies acceptance of the ideas contained within. Reproduced with permission from Raschke Seedling crown orientation and interception of diffuse radiation in tropical forest gaps.
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