Flowers anticipate revisits of pollinators by learning from previously experienced visitation intervals

Consciousness and cognition in plants

Unlike animal behavior, behavior in plants is traditionally assumed to be completely determined either genetically or environmentally. Under this assumption, plants are usually considered to be noncognitive organisms. This view nonetheless clashes with a growing body of empirical research that shows that many sophisticated cognitive capabilities traditionally assumed to be exclusive to animals are exhibited by plants too. Yet, if plants can be considered cognitive, even in a minimal sense, can they also be considered conscious? Some authors defend that the quest for plant consciousness is worth pursuing, under the premise that sentience can play a role in facilitating plant's sophisticated behavior. The goal of this article is not to provide a positive argument for plant cognition and consciousness, but to invite a constructive, empirically informed debate about it. After reviewing the empirical literature concerning plant cognition, we introduce the reader to the emerging field of plant neurobiology. Research on plant electrical and chemical signaling can help shed light into the biological bases for plant sentience. To conclude, we shall present a series of approaches to scientifically investigate plant consciousness. In sum, we invite the reader to consider the idea that if consciousness boils down to some form of biological adaptation, we should not exclude a priori the possibility that plants have evolved their own phenomenal experience of the world. This article is categorized under: Cognitive Biology > Evolutionary Roots of Cognition Philosophy > Consciousness Neuroscience > Cognition.

Plant behaviour: an evolutionary response to the environment?

Plants are not just passive living beings that exist in nature. They are complex and highly adaptable species that react sensitively to environmental forces/stimuli with movement, morphological changes and through the communication via volatile molecules. In a way, plants mimic some traits of animal and human behaviour; they compete for limited resources by gaining more area for more sunlight and spread their roots underground. Furthermore, in order to survive and thrive, they evolve and 'learn' to control various environmental stress factors in order to increase the yield of flowering, fertilization and germination processes. The concept of associating complex behaviour, such as intelligence, with plants is still a highly debatable topic among researchers worldwide. Recent studies have shown that plants are able to discriminate between positive and negative experiences and 'learn' from them. Some botanists have interpreted these behavioural data as a form of primitive cognitive processes. Others have evaluated these responses as biological automatisms of plants determined by adaptation to the environment and absence of intelligence. This review aims to explore adaptive behavioural aspects of various plant species distributed in different ecosystems by emphasizing their biological complexity and survival instincts.

Specialised protagonists in a plant-pollinator interaction: the pollination of Blumenbachia insignis (Loasaceae)

Analyses of resource presentation, floral morphology and pollinator behaviour are essential for understanding specialised plant-pollinator systems. We investigated whether foraging by individual bee pollinators fits the floral morphology and functioning of Blumenbachia insignis, whose flowers are characterised by a nectar scale-staminode complex and pollen release by thigmonastic stamen movements. We described pollen and nectar presentation, analysed the breeding system and the foraging strategy of bee pollinators. We determined the nectar production pattern and documented variations in the longevity of floral phases and stigmatic pollen loads of pollinator-visited and unvisited flowers. Bicolletes indigoticus (Colletidae) was the sole pollinator with females revisiting flowers in staminate and pistillate phases at short intervals, guaranteeing cross-pollen flow. Nectar stored in the nectar scale-staminode complex had a high sugar concentration and was produced continuously in minute amounts (~0.09 μl·h^-1 ). Pushing the scales outward, bees took up nectar, triggering stamen movements and accelerating pollen presentation. Experimental simulation of this nectar uptake increased the number of moved stamens per hour by a factor of four. Flowers visited by pollinators received six-fold more pollen on the stigma than unvisited flowers, had shortened staminate and pistillate phases and increased fruit and seed set. Flower handling and foraging by Bicolletes indigoticus were consonant with the complex flower morphology and functioning of Blumenbachia insignis. Continuous nectar production in minute quantities but at high sugar concentration influences the pollen foraging of the bees. Partitioning of resources lead to absolute flower fidelity and stereotyped foraging behaviour by the sole effective oligolectic bee pollinator.