The Pollination of Manihot
esculenta (yuca) and It’s
Importance to Archeology: A
Beginning Study
Elizabeth Georgian
Introduction
• Yuca belongs to the family
Euphorbiacea and the genus Manihot
• Yuca is one of the world’s most
productive crop plants in terms of
calories
• There are two types of manioc: the
bitter and the sweet
http://www.nationaalherbarium.nl/euphorbs/specM/Manihot.htm
Introduction continued
• Yuca is planted by use of stem cuttings
• Most Amerindian cultivators plant
several different varieties of yuca
• Why are there so many different
varieties of yuca, if the only method of
planting is by use of stem cuttings?
Review of Pollination
http://dbs.umt.edu/courses/sci226/lab4_plantsanimals.htm
Review of Pollination
continued
• Pollen from the stamen lands on the
stigma
• The pollen grain conveys the genetic
material down the style to the ovary
• After fertilization the ovule develops into
a seed and the ovary develops into the
surrounding fruit
Creating new varieties
• Amerindians have many different
varieties of yuca
• Cloning is important for maintaining the
stock of one variety
Creating new varieties
continued
• New varieties of yuca are created through
sexual reproduction
• Thus, when different varieties reproduce
together, new varieties are created
• Some varieties will be superior and may
continue to be cultivated through stem
cuttings
• Other varieties will be inferior and will be lost
Seed dispersal
• Most varieties produce flowers which,
after pollination, produce a fruit and
three viable seeds (Elias et al 2000)
• The fruit dries in the sun and dehisces,
sending the seeds flying to the ground
Seed dispersal continued
• Ants disperse the seeds which have
been propelled to the ground
• The ants feed their larvae nutrients from
the seed appendage (Elias and Mckey 2000)
• After used, the seed is discarded in a
waste pile where it waits until the
appropriate germination requirements
are met
Spontaneous seedlings
• The spontaneous seedlings are not
weeded by Amerindians
• If the spontaneous seedling produces
tubers that are deemed desirable, the
new variety will be propagated by stem
cuttings
Archeology and Paleobotany
• Paleobotanists work to recover, identify
and classify plant remains
• Paleobotanists and archeologists could
work together to uncover more
information about ancient yuca
Why is pollination important to
archeology?
• Pollen can be found at archeological
sites
• This can help determine where ancient
manioc was located
Archeology and Pollen
• Manihot fossil pollen has been found at
a number of sites
• A grain of pollen was found in the costal
region of Tabasco, Mexico (Bartlett et al 1969)
• Pollen also was found in Panama (Dickau et
al 2007)
What other methods could be
employed to clarify the
relationships and unknown
data on Manihot esculenta?
• Systematics
• Microfossils
• Macrofossils
Systematics
• Systematics is the study of relationships
between species of plants
• Systematics could help end some
confusion relating to relationships in the
Manihot genus
Microfossils
• Microfossils are fossils that are
microscopic
• Examples of microfossils include pollen,
phytoliths and starch grains
Macrofossils
• Preserved remains of yuca and artifacts
pointing to the domestication of yuca
can be considered macrofossils
Remaining Questions
• What is the type of pollinator? Bird?
Insect? Wind?
• What is the species of pollinator?
• What are the systematic relationships of
the varieties?
• What are the exact germination
requirements?
Acknowledgements
• I want to sincerely thank Dr. Robert Carneiro,
without whom this great opportunity would not
have arisen.
• I would also like to thank the Second
Symposium of the Program for Molecular
Archaeology, Sciences and Engineering
Applied to Studies of the Past committee for
welcoming me to their lovely campus and for
graciously inviting me to this conference.
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