Pollen and Phytoliths
by Jamie Civitello
Palynology (pollen analysis) has been used by North American environmental archaeologists for decades but its function has evolved from simply providing broad scale paleoenvironmental reconstructions to examining more closely the changing relationships between people and vegetation. Phytolith analysis has been used to a lesser extent, but is increasing. Both can be used to elucidate both the sequence of vegetation history and also the composition of agricultural fields and gardens, which allow our interpretations to account for the dynamic ways in which humans have manipulated their environs.
Pollen
Seed-bearing plants produce pollen grains, which are transported by wind, water, insects, etc. to eventually become deposited in various contexts. Pollen grains have a resilient outer layer called the exine that can survive for millions of years. The shape of the exine is unique to each type of plant, often on the genus and species level, so that the shape and pattern of the exine provides a plant signature. Samples of soil are taken back to a laboratory and chemically processed to remove dirt debris, leaving behind pollen for identification. Amounts of different pollen throughout different deposits indicate a change in vegetation over time.
Archaeologists learn from pollen analysis in several ways. "Pollen rain," the overall airborne pollen at any given time, sampled from lakes and bogs, informs about regional paleoenvironments (past environments). Pollen mixed in with archaeological soils can often indicate plant assemblages that are more local to the area. Ceramic and stone artifacts may retain intact traces of pollen or phytoliths, from which we can discern diet and numerous cultural activities. With regard to ancient and historic agriculture and gardens in the Southeastern United States, the first two instances of pollen analysis are most informative.
Regional paleoenvironmental histories via the pollen record show that the Southeastern forest changed over the past 10,000 years since the end of the Ice Age; through time, mixed hardwood deciduous trees were supplanted by mixed pine and hardwood deciduous forests. Native Americans managed their landscape by clearing gaps in the forest with fire for many reasons, including preparation of garden plots where crops such as maize, chenopod, and maygrass would flourish; burning forests also let the fire-loving pine tree spread.
Charcoal and pollen studies at Cliff Palace Pond, Kentucky, link an increase in both episodes of fire and weedy plant pollen to known Late Archaic and Woodland period gardening. As maize agriculture became a mode of subsistence in Mississippian times, clearing intensified and the pine tree/ weedy seed pollen patterns become emphasized in the archaeological record.
Phytoliths
All plants produce hard, crystalline structures around their cells called phytoliths. Plants have thousands of these and when the plant dies, the structures stay behind in the soil. Like pollen, each plant or group of plants has its own signature structure. Consequently, identification of phytoliths in archaeological samples can tell us about the plants in the area. For instance, maize phytoliths are very distinctive and have been used to locate Native American agricultural fields. Since phytoliths are incorporated into the dirt when a plant rots, they can aid in reconstruction of actual garden fields and grounds. When the grounds around Thomas Jefferson’s home at Monticello were sampled for phytoliths, archaeologists were able to pinpoint fields and identify which European plants were introduced there.
Pollen
Seed-bearing plants produce pollen grains, which are transported by wind, water, insects, etc. to eventually become deposited in various contexts. Pollen grains have a resilient outer layer called the exine that can survive for millions of years. The shape of the exine is unique to each type of plant, often on the genus and species level, so that the shape and pattern of the exine provides a plant signature. Samples of soil are taken back to a laboratory and chemically processed to remove dirt debris, leaving behind pollen for identification. Amounts of different pollen throughout different deposits indicate a change in vegetation over time.
Archaeologists learn from pollen analysis in several ways. "Pollen rain," the overall airborne pollen at any given time, sampled from lakes and bogs, informs about regional paleoenvironments (past environments). Pollen mixed in with archaeological soils can often indicate plant assemblages that are more local to the area. Ceramic and stone artifacts may retain intact traces of pollen or phytoliths, from which we can discern diet and numerous cultural activities. With regard to ancient and historic agriculture and gardens in the Southeastern United States, the first two instances of pollen analysis are most informative.
Regional paleoenvironmental histories via the pollen record show that the Southeastern forest changed over the past 10,000 years since the end of the Ice Age; through time, mixed hardwood deciduous trees were supplanted by mixed pine and hardwood deciduous forests. Native Americans managed their landscape by clearing gaps in the forest with fire for many reasons, including preparation of garden plots where crops such as maize, chenopod, and maygrass would flourish; burning forests also let the fire-loving pine tree spread.
Charcoal and pollen studies at Cliff Palace Pond, Kentucky, link an increase in both episodes of fire and weedy plant pollen to known Late Archaic and Woodland period gardening. As maize agriculture became a mode of subsistence in Mississippian times, clearing intensified and the pine tree/ weedy seed pollen patterns become emphasized in the archaeological record.
Phytoliths
All plants produce hard, crystalline structures around their cells called phytoliths. Plants have thousands of these and when the plant dies, the structures stay behind in the soil. Like pollen, each plant or group of plants has its own signature structure. Consequently, identification of phytoliths in archaeological samples can tell us about the plants in the area. For instance, maize phytoliths are very distinctive and have been used to locate Native American agricultural fields. Since phytoliths are incorporated into the dirt when a plant rots, they can aid in reconstruction of actual garden fields and grounds. When the grounds around Thomas Jefferson’s home at Monticello were sampled for phytoliths, archaeologists were able to pinpoint fields and identify which European plants were introduced there.
The views and opinions expressed in this page are strictly those of the page author. The contents of the page have not been reviewed or approved by the University of South Carolina. Page last updated 13 Sept. 2014.