![Agrostology
• Agrostology [Greek, a kind of grass + body of knowledge] is the
branch of systematic botany that deals with grasses, especially their
identification, classification, and evolution.
• Agriculture, on the other hand, is the applied science that deals with
cultivating land, and the raising and breeding of crops and livestock.
• Agronomy is the science of soil management and of crop production.
Both terms are derived from the Greek root for fields, soils, and
crops.](https://image.slidesharecdn.com/agrostologyintrolecture1and2-250306051124-c784a07d/85/AGROSTOLOGY-introduction-Lecture-1-and-2-pdf-2-320.jpg)
![THE RECORD OF ANCIENT GRASSES
AND GRASSLANDS
• Both direct and indirect records have contributed to shaping our view of
ancient grasses and grasslands.
• The direct record of grasses, including macrofossils (fossilized leaves,
stems, reproductive structures) and microfossils [pollen, plant silica bodies
(phytoliths)].
• Several indirect proxies have also been applied to track the evolutionary
history of grasses.
• For example, mammalian functional morphology has long been used to
infer grass-dominated habitats, based on the assumption that traits
common in mammals that eat grasses or live in grasslands today (powerful
chewing muscles, long legs, large body size, tooth morphology) evolved in
response to the spread of this new vegetation type ( Jacobs et al. 1999).](https://image.slidesharecdn.com/agrostologyintrolecture1and2-250306051124-c784a07d/85/AGROSTOLOGY-introduction-Lecture-1-and-2-pdf-16-320.jpg)
AGROSTOLOGY introduction Lecture 1 and 2.pdf
- 1. AGROSTOLOGY
- 2. Agrostology • Agrostology [Greek, a kind of grass + body of knowledge] is the branch of systematic botany that deals with grasses, especially their identification, classification, and evolution. • Agriculture, on the other hand, is the applied science that deals with cultivating land, and the raising and breeding of crops and livestock. • Agronomy is the science of soil management and of crop production. Both terms are derived from the Greek root for fields, soils, and crops.
- 3. WHAT ARE GRASSES? • All true grasses belong to a single family of flowering plants, Gramineae or Poaceae. • "true grasses" because there are many plants that have "grass" as part of their common name that are not, in fact, grasses. HOW BIG IS THE FAMILY? • Grasses, although they do not constitute the largest family of flowering plants, are economically the most important to us. • Estimates of the size of the family vary, but ranges of 600-700 genera and about 10,000 species seem reasonable. • The family ranks third in number of genera (behind the orchids and sunflowers) and fifth in number of species (after orchids, sunflowers, legumes, and members of the madder family).
- 4. DISTRIBUTION • Grasses are the most cosmopolitan of all higher plants, occurring on all continents, including Antarctica. • They are found from the polar regions to the equator, from mountain tops to seashores. • They occur in brackish and freshwater marshes, ponds, streams, rain forests, deserts, tundra, and arid slopes. • About one-fourth of the earth's plant cover is grasslands. Source: http://timelessenvironments.blogspot.com/2012/07/
- 5. ECONOMIC IMPORTANCE • No other plant family, with the possible exception of the legumes and palms, can approach the grasses in direct economic importance to us. • Major products include the cereal grains (wheat, rice, maize, barley, rye, sorghum, oats, and millets), hay, pasture, turf grasses, thatching material, timber, paper pulp, sugar (from sugar cane and sorghum), aromatic compounds (e. g., lemon grass and oil of vetiver), brooms, fishing poles, musical instruments, ornamentals, soil binders, starches, edible oils, alcohol, beverages, and food for most of the world's wild and domesticated animals. • We derive a major portion of our calories from cereals. Much of our agricultural land is devoted to the raising of cereals, especially wheat. Still more of the earth's surface is used for pastures for a variety of domesticated animals.
- 6. True Grasses • True grasses belong to the family Poaceae, also known as the Gramineae family. • Examples of true grasses include wheat, rice, corn (maize), barley, oats, rye, sugarcane, and many types of turf grasses like Bermuda grass, Kentucky bluegrass. • True grasses are monocots, which means they have a single embryonic leaf (cotyledon) when they sprout, and their leaves usually have parallel venation. • They are important as staple food crops for humans and as forage for livestock. They also serve as lawn and turf grasses and have various other industrial and ecological uses. Source: https://ecosystemsunited.com/2016/03/14/
- 7. False Grasses • False grasses are not true grasses; they belong to different plant families that may resemble true grasses but are botanically distinct. • Some plants referred to as false grasses belong to the Cyperaceae family, commonly known as the sedge family. Sedges are often found in wetland habitats and have triangular stems, and their leaves are arranged in sets of three in a spiral pattern. • Another group of plants referred to as false grasses may belong to the Juncaceae family, known as the rush family. Rushes are typically found in moist environments and have round, smooth stems and grass-like leaves with a basal sheath. • Examples of false grasses include papyrus (a type of sedge), bulrushes (another type of sedge), and various species of rushes like soft rush and hard rush. Juncaceae (Rushes) Cypraceae (Sedges)
- 8. • Grasses have round stems, like rushes, but they are hollow. They also have nodes along the stems. Nodes are areas where the leaf sheath ends, and there is a small swelling. Source: https://extension.illinois.edu/blogs/
- 9. • In general, rushes have stems that are round. Like the sedges, the stems do not have nodes and are not hollow. Rushes also have zero to a few leaves along their stems. Source: https://extension.illinois.edu/blogs/
- 10. • Many sedges have triangular shaped stems, giving them edges. This is easily felt by rolling the stem between your fingers. • They don’t have any nodes along their stems, and the stems are not hollow. Sedges with triangular stems have three ranked leaves, which means the leaves are arranged on all three sides of the stem. Source: https://extension.illinois.edu/blogs/
- 11. • Kingdom: Plantae • Phylum: Angiosperms (Flowering Plants) • Class: Monocots (Monocotyledons) • Order: Poales • Family: Poaceae (Gramineae) Source: https://ohioplants.org/families-poaceae/
- 12. Origin of Grasses • Grasses are angiosperms, or flowering plants, and they share a common ancestry with all flowering plants. • The first angiosperms appeared during the early Cretaceous period, approximately 140 million years ago. • These early angiosperms were quite different from modern grasses, but they laid the foundation for their evolution.
- 13. Emergence of Grass Ancestors (Around 100-80 Million Years Ago) • The direct ancestors of grasses are believed to have evolved from within the group of plants known as the Poales order. • This order also includes sedges (Cyperaceae) and rushes (Juncaceae). • Grasses, sedges, and rushes are all monocots, characterized by having a single cotyledon (seed leaf) and leaves with parallel venation.
- 14. Evolution of True Grasses (Around 60-80 Million Years Ago): • True grasses, or Poaceae, began to diversify during the late Cretaceous and early Paleocene epochs, around 60-80 million years ago. • These early grasses were quite different from the grasses we are familiar with today. • They often had woody or vine-like forms and may not have been immediately recognizable as grasses.
- 15. Grass Evolution and Adaptation (Throughout Geological Eras) • Grasses evolved various adaptations that contributed to their success. • Their adaptability, including their ability to thrive in diverse environments, is partly attributed to the development of C4 photosynthesis, which is a highly efficient way to assimilate carbon dioxide, conserve water, and resist heat. • This adaptation allowed grasses to become dominant in many ecosystems.
- 16. THE RECORD OF ANCIENT GRASSES AND GRASSLANDS • Both direct and indirect records have contributed to shaping our view of ancient grasses and grasslands. • The direct record of grasses, including macrofossils (fossilized leaves, stems, reproductive structures) and microfossils [pollen, plant silica bodies (phytoliths)]. • Several indirect proxies have also been applied to track the evolutionary history of grasses. • For example, mammalian functional morphology has long been used to infer grass-dominated habitats, based on the assumption that traits common in mammals that eat grasses or live in grasslands today (powerful chewing muscles, long legs, large body size, tooth morphology) evolved in response to the spread of this new vegetation type ( Jacobs et al. 1999).
- 17. Challenges in the Fossil Record of Grasses • Grasses that live in dry and open areas, called 'upland' grasses, don't often leave behind fossil evidence like pollen and plant remains because these environments are not good at preserving them. • Plants like grasses, which are not woody, are often not commonly found in collections of ancient plant remains. • Macro remains of Poaceae (grass family) often lack well-preserved cells, which can make it challenging to differentiate them from closely related monocotyledonous plants. • Grass pollen tends to break down over time, especially in dry soil, which can create a bias against grasses in ancient pollen records. • Pollen morphology is uniform within Poaceae so it's challenging to distinguish between different types of grasses at levels below the family.
- 18. Phytoliths: Filling the Gaps in the Fossil Record of Grasses Phytoliths are microscopic, rigid, and often silica-based structures that form within the cells of various plants, including grasses, trees, and other vegetation. The term "phytolith" is derived from the Greek words "phyton," meaning plant, and "lithos," meaning stone, reflecting their mineralized or stony nature. Source: https://regandunn.org/phytoliths/
- 19. • Tiny silica particles called phytoliths, found in many plants, are now providing direct evidence for grasses in the Cenozoic era. • These phytoliths can sometimes tell us exactly which genus of grass they came from, and they are reliable indicators of how many grasses versus trees existed in different ecosystems. • What's remarkable is that they can survive in well-oxidized sediment types where we often can't find pollen or larger plant fossils.