Theophrastus
Aristotle's student described and classified about 500 plants by form, growth and use in Enquiry into Plants.
Why it matters: The first systematic plant science; he is called the father of botany.
📄 Theophrastus. Historia Plantarum (Enquiry into Plants), c. 300 BCE.
Jan Baptist van Helmont
A willow grew from 5 lb to 169 lb in 5 years while its soil lost only 2 oz. He concluded the mass came from water.
Why it matters: First quantitative plant experiment — half right: most of the mass actually comes from CO₂ in the air.
📄 van Helmont JB. Ortus Medicinae. Amsterdam, 1648.
Robert Hooke
Saw the box-like walls of dead cork cells and named them cells.
Why it matters: The start of plant (and all) cell biology.
📄 Hooke R. Micrographia. London, 1665.
Rudolf Jakob Camerarius
Showed experimentally that pollen is needed for seeds to form — stamens are male organs, the pistil female.
Why it matters: Proved sexual reproduction in plants.
📄 Camerarius RJ. De Sexu Plantarum Epistola. Tübingen, 1694.
Stephen Hales
Measured water loss from leaves (transpiration), root pressure and sap flow, and suggested that air contributes to plant nourishment.
Why it matters: Founded plant physiology as a measuring science.
📄 Hales S. Vegetable Staticks. London, 1727.
Carl Linnaeus
Gave every known plant species a two-part Latin name.
Why it matters: The official starting point of plant naming today.
📄 Linnaeus C. Species Plantarum. Stockholm, 1753.
Joseph Priestley; Jan Ingenhousz
Priestley found a mint sprig ‘restored’ air a candle had used up. Ingenhousz showed this needs light and happens in green parts.
Why it matters: Discovery of photosynthesis.
📄 Ingenhousz J. Experiments upon Vegetables. London, 1779.
Nicolas-Théodore de Saussure
Careful weighing showed plants gain carbon from CO₂ and also incorporate water.
Why it matters: Completed the basic equation of photosynthesis.
📄 de Saussure NT. Recherches chimiques sur la végétation. Paris, 1804.
Matthias Schleiden
Concluded that all plant tissues are made of cells; with Schwann (1839) this became cell theory.
Why it matters: A unifying principle of biology.
📄 Schleiden MJ. Beiträge zur Phytogenesis. Archiv für Anatomie, 1838.
Gregor Mendel
Crosses of pea plants revealed the rules of inheritance.
Why it matters: Plants gave us genetics.
📄 Mendel G. Verh. Naturforsch. Ver. Brünn 4 (1866).
Charles & Francis Darwin
Showed grass seedlings bend toward light only if the tip is lit — a signal travels down from the tip.
Why it matters: Led to the discovery of auxin, the first plant hormone.
📄 Darwin C. The Power of Movement in Plants. London, 1880.
Sergei Nawaschin
In lilies, one sperm fertilises the egg and a second fuses with the polar nuclei to form endosperm.
Why it matters: Explains how seeds get their food store — unique to flowering plants.
📄 Nawaschin S. Bull. Acad. Imp. Sci. St.-Pétersbourg 9 (1898).
Frederick Blackman
The rate of a process is limited by the factor in shortest supply — light, CO₂ or temperature.
Why it matters: The idea behind the photosynthesis lab in this module.
📄 Blackman FF. Optima and limiting factors. Annals of Botany 19 (1905).
Frits Went
Collected the growth substance from oat tips in agar blocks and measured its effect.
Why it matters: Proved plant hormones exist.
📄 Went FW. Rec. Trav. Bot. Néerl. 25 (1928).
Ernst Münch
Proposed that sugars move in phloem by mass flow from sources (leaves) to sinks (roots, fruits).
Why it matters: Still the accepted model of phloem transport.
📄 Münch E. Die Stoffbewegungen in der Pflanze. Jena, 1930.
Samuel Ruben & Martin Kamen
Using the isotope ¹⁸O they showed the oxygen released comes from H₂O, not CO₂.
Why it matters: Clarified the chemistry of the light reactions.
📄 Ruben S et al. J. Am. Chem. Soc. 63:877 (1941).
Melvin Calvin, Andrew Benson, James Bassham
Radioactive ¹⁴C traced the path of carbon from CO₂ into sugars in algae.
Why it matters: How plants build sugar; Nobel Prize 1961.
📄 Bassham JA, Benson AA, Calvin M. J. Biol. Chem. 185:781 (1950).
Peter Mitchell
ATP is made by a proton gradient across a membrane — in chloroplasts and mitochondria.
Why it matters: Explained energy capture; Nobel 1978.
📄 Mitchell P. Nature 191:144 (1961).
Hatch & Slack (building on Kortschak, Karpilov)
Maize and sugar cane first fix CO₂ into 4-carbon acids and concentrate it around Rubisco.
Why it matters: Explains why some crops are so productive in heat.
📄 Hatch MD, Slack CR. Biochem. J. 101:103 (1966).
Norman Borlaug and others
Semi-dwarf, disease-resistant wheat and rice with fertiliser and irrigation doubled yields in many countries (Borlaug: Nobel Peace Prize 1970).
Why it matters: Fed hundreds of millions, at environmental cost.
📄 Borlaug NE. Nobel lecture, 1970.
Several groups (Fraley, Bevan, Herrera-Estrella…)
Agrobacterium was used to insert foreign genes into tobacco and petunia.
Why it matters: Start of plant genetic engineering.
📄 Fraley RT et al. PNAS 80:4803 (1983).
Enrico Coen & Elliot Meyerowitz
Three classes of genes in combination decide sepal, petal, stamen or carpel.
Why it matters: How a flower is built genetically.
📄 Coen ES, Meyerowitz EM. Nature 353:31 (1991).
Arabidopsis Genome Initiative
The ~135 million base-pair genome of thale cress, Arabidopsis thaliana.
Why it matters: The reference genome for plant biology.
📄 Arabidopsis Genome Initiative. Nature 408:796 (2000).
Akiyama et al.; Gomez-Roldan et al.; Umehara et al.
Strigolactones were found to signal from roots to mycorrhizal fungi (2005) and then to act as hormones that stop shoots branching (2008).
Why it matters: A new hormone class linking branching and soil partners.
📄 Akiyama K et al. Nature 435:824 (2005); Gomez-Roldan V et al.; Umehara M et al. Nature 455 (2008).
Several groups
First CRISPR-Cas9 gene edits in rice, wheat, tobacco and Arabidopsis.
Why it matters: Precise crop improvement without adding foreign genes.
📄 Shan Q et al. Nat. Biotechnol. 31:686 (2013).
Paul South, Amanda Cavanagh, Donald Ort and others
Tobacco with an engineered bypass of photorespiration grew about 40% more biomass in field trials.
Why it matters: Showed photosynthesis itself can be improved.
📄 South PF et al. Science 363:eaat9077 (2019).
Amanda De Souza, Stephen Long and others
Speeding the switch-off of light protection when leaves fall into shade raised yield by up to ~33% in some field seasons.
Why it matters: Field proof of a photosynthesis-boosting crop.
📄 De Souza AP et al. Science 377:851 (2022).