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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| History of botany | 8/10 | https://en.wikipedia.org/wiki/History_of_botany | reference | science, encyclopedia | 2026-05-05T03:59:20.683361+00:00 | kb-cron |
The opening of the 19th century was marked by an increase in interest in the connection between climate and plant distribution. Carl Willdenow (1765–1812) examined the connection between seed dispersal and distribution, the nature of plant associations and the impact of geological history. He noticed the similarities between the floras of N America and N Asia, the Cape and Australia, and he explored the ideas of "centre of diversity" and "centre of origin". German Alexander von Humboldt (1769–1859) and Frenchman Aime Bonpland (1773–1858) published a massive and highly influential 30 volume work on their travels; Robert Brown (1773–1852) noted the similarities between the floras of S Africa, Australia and India, while Joakim Schouw (1789–1852) explored more deeply than anyone else the influence on plant distribution of temperature, soil factors, especially soil water, and light, work that was continued by Alphonse de Candolle (1806–1893). Joseph Hooker (1817–1911) pushed the boundaries of floristic studies with his work on Antarctica, India and the Middle East with special attention to endemism. August Grisebach (1814–1879) in Die Vegetation der Erde (1872) examined physiognomy in relation to climate and in America geographic studies were pioneered by Asa Gray (1810–1888). Physiological plant geography, or ecology, emerged from floristic biogeography in the late 19th century as environmental influences on plants received greater recognition. Early work in this area was synthesised by Danish professor Eugenius Warming (1841–1924) in his book Plantesamfund (Ecology of Plants, generally taken to mark the beginning of modern ecology) including new ideas on plant communities, their adaptations and environmental influences. This was followed by another grand synthesis, the Pflanzengeographie auf Physiologischer Grundlage of Andreas Schimper (1856–1901) in 1898 (published in English in 1903 as Plant-geography upon a physiological basis translated by W. R. Fischer, Oxford: Clarendon press, 839 pp).
=== Anatomy ===
During the 19th century, German scientists led the way towards a unitary theory of the structure and life-cycle of plants. Following improvements in the microscope at the end of the 18th century, Charles Mirbel (1776–1854) in 1802 published his Traité d'Anatomie et de Physiologie Végétale and Johann Moldenhawer (1766–1827) published Beyträge zur Anatomie der Pflanzen (1812) in which he describes techniques for separating cells from the middle lamella. He identified vascular and parenchymatous tissues, described vascular bundles, observed the cells in the cambium, and interpreted tree rings. He found that stomata were composed of pairs of cells, rather than a single cell with a hole. Anatomical studies on the stele were consolidated by Carl Sanio (1832–1891), who described the secondary tissues and meristem including cambium and its action. Hugo von Mohl (1805–1872) summarized work in anatomy leading up to 1850 in Die Vegetabilische Zelle (1851) but this work was later eclipsed by the encyclopaedic comparative anatomy of Heinrich Anton de Bary in 1877. An overview of knowledge of the stele in root and stem was completed by Van Tieghem (1839–1914) and of the meristem by Carl Nägeli (1817–1891). Studies had also begun on the origins of the carpel and flower that continue to the present day.
=== Water relations ===
The riddle of water and nutrient transport through the plant remained. Physiologist Von Mohl explored solute transport and the theory of water uptake by the roots using the concepts of cohesion, transpirational pull, capillarity and root pressure. German dominance in the field of experimental physiology, largely influenced by Wilhelm Knop and Julius von Sachs, was underlined by the publication of the definitive textbook on plant physiology synthesising the work of this period, Sachs' Vorlesungen über Pflanzenphysiologie of 1882. There were, however, some advances elsewhere, such as the early exploration of geotropism (the effect of gravity on growth) by Englishman Thomas Knight, and the discovery and naming of osmosis by Frenchman Henri Dutrochet (1776–1847). The American Dennis Robert Hoagland (1884–1949) discovered the dependence of nutrient absorption and translocation by the plant on metabolic energy.
=== Cytology ===
The cell nucleus was discovered by Robert Brown in 1831. Demonstration of the cellular composition of all organisms, with each cell possessing all the characteristics of life, is attributed to the combined efforts of botanist Matthias Jakob Schleiden and zoologist Theodor Schwann (1810–1882) in the early 19th century, although Moldenhawer had already shown that plants were wholly cellular with each cell having its own wall and Julius von Sachs had shown the continuity protoplasm between cell walls. From 1870 to 1880, it became clear that cell nuclei are never formed anew but always derived from the substance of another nucleus. In 1882, Walther Flemming observed the longitudinal splitting of chromosomes in the dividing nucleus and concluded that each daughter nucleus received half of each of the chromosomes of the mother nucleus: then by the early 20th century, it was found that the number of chromosomes in a given species is constant. With genetic continuity confirmed and the finding by Eduard Strasburger that the nuclei of reproductive cells (in pollen and embryo) have a reducing division (halving of chromosomes, now known as meiosis) the field of heredity was opened up. By 1926, Thomas Morgan was able to outline a theory of the gene and its structure and function. The form and function of plastids received similar attention, the association with starch being noted at an early date. Later, the cytological basis of the gene-chromosome theory of heredity extended from about 1900–1944 and was initiated by the rediscovery of Gregor Mendel's (1822–1884) laws of plant heredity first published in 1866 in Experiments on Plant Hybrids and based on cultivated pea Pisum sativum; this heralded the opening up of plant genetics. The cytological basis for gene-chromosome theory was explored through the role of polyploidy and hybridisation in speciation and it was becoming better understood that interbreeding populations were the unit of adaptive change in biology.
=== Developmental morphology and evolution ===