Thursday Lecture – Leaf, Stem
and Root Crops
Reading: Textbook, Chapter 7
Baby carrots – a product of the
“Soccer Mom” age
Baby carrots are produced by using specially bred forms that
produce a long, thin storage root. The roots are carefully
selected to eliminate discolored or malformed ones, and then are
sliced into short pieces (2-3 inches). The pieces are further
checked for color (they must have no hint of green) and are sent
through a lathe device that smoothes the ends. The final product
is ready to eat in a convenient form.
Quiz
Quiz
1. Name a vegetable for each category of what we
actually eat:
petiole:
entire leaf:
inflorescence:
2. Where was the potato domesticated? What part
of the plant do we eat?
Asparagus – Eat Your Lilies
See Fig. 7.25,
p. 177
Onions – Allium cepa
See Fig. 7.27,
p. 179
Leeks – Another Allium
See Fig. 7.27,
p. 179
Bulbs
Succulent
Storage Leaves
Stem
Adventitious Roots
Big buds
on short stems
Corms: short fat
underground stems
Rhizomes: simple underground stems
Hydrocotyle
Petioles
reach above
the sand
Nodes
Adventitious Roots
Apex
of
Rhizome
Tubers:
swollen ends of
rhizomes
Corm - Crocus
STEMS
Tuber - potato
Bulb onion
Irish Potato
Solanum
tuberosum
The Amazing Spud
- The potato is a short duration crop that produces a large amount
of calories in a short period of time
- The potato produces more protein and calories per unit area per
unit time and per unit of water than any other major plant food.
- The ratio of protein to calories, the quality of the protein and the
high levels of vitamins and minerals are assets greatly needed in
many countries.
Potatoes – South American Staple
Potatoes – South American Staple
Potatoes – South American Staple
Potatoes – South American Staple
Potatoes Travel to Europe
Frederick the Great encouraging
peasants to grow more potatoes
Potatoes Travel to Europe
Frederick the Great encouraging
peasants to grow more potatoes
Potatoes Travel to Europe
Frederick the Great encouraging
peasants to grow more potatoes
Vincent van Gogh painting: “The
potato eaters” (Belgium)
Potato Blight
Healthy leaf
Potato Blight
Healthy leaf
Potato Blight: Phytophthora infestans
(fungus)
Blighted leaf
Potato Blight
Healthy leaf
Potato Blight: Phytophthora infestans
(fungus)
Potatoes damaged by blight
Blighted leaf
The Irish Potato Blight
Ireland – potato became staple crop in 1800s
The Irish Potato Blight
Ireland – potato became staple crop in 1800s
functionally monoculture – political & cultural considerations
1840s – potato blight hit: population 8 million  6 million
The Irish Potato Blight
Ireland – potato became staple crop in 1800s
functionally monoculture – political & cultural considerations
1840s – potato blight hit: population 8 million  6 million
- 1 million people died; 1.5 million people immigrated to Australia
& U.S.A.
Potato Culture – Increasing
Mechanization
Holland Potato Farms 100 years apart
1870
1970
Improving Potato Yields
Despite appearances, not yet a priority for the Green Revolution
Tropical Starchy Staples
True Yam
Dioscorea sp.
Taro
Colocasia esculenta Asia  tropical Pacific
Yautia
Xanthosoma sp.
South America
Arrowroot
Maranta sp.
West Indies/South America
Manioc
Manihot esculenta
South America
Sweet Potato Ipomoea batatas
Africa, Asia, South America
South America
Tropical Starchy Staples
True Yam
Dioscorea sp.
Taro
Colocasia esculenta Asia  tropical Pacific
Yautia
Xanthosoma sp.
South America
Arrowroot
Maranta sp.
West Indies/South America
Manioc
Manihot esculenta
South America
Sweet Potato Ipomoea batatas
Tubers
Africa, Asia, South America
South America
Tropical Starchy Staples
True Yam
Dioscorea sp.
Taro
Colocasia esculenta Asia  tropical Pacific
Yautia
Xanthosoma sp.
South America
Arrowroot
Maranta sp.
West Indies/South America
Manioc
Manihot esculenta
South America
Sweet Potato Ipomoea batatas
Tubers
Roots
Africa, Asia, South America
South America
Yams – Another Tuber
Dioscorea sp.
Monocot vines – different species
domesticated independently in
various tropical areas
Taro – Food from a Corm
Taro – Food from a Corm
Taro – Food from a Corm
Starchy Root Crops – Manioc (Cassava)
Cassava – Food for the “Poorest of
the Poor”
Staple food for >500 million people
Cassava – Food for the “Poorest of
the Poor”
Staple food for >500 million people
Cassava – Food for the “Poorest of
the Poor”
Staple food for >500 million people
Most calories per unit area of land (except for sugar cane)
Cassava – Food for the “Poorest of
the Poor”
Staple food for >500 million people
Most calories per unit area of land (except for sugar cane)
Grows in poor soils
Cassava – Food for the “Poorest of
the Poor”
Staple food for >500 million people
Most calories per unit area of land (except for sugar cane)
Grows in poor soils
Primarily carbohydrate – low in protein, minerals, vitamins
Cassava – Food for the “Poorest of
the Poor”
Staple food for >500 million people
Most calories per unit area of land (except for sugar cane)
Grows in poor soils
Primarily carbohydrate – low in protein, minerals, vitamins
Cyanogenic glycosides must be removed before consumption
Cassava – Food for the “Poorest of
the Poor”
Staple food for >500 million people
Most calories per unit area of land (except for sugar cane)
Grows in poor soils
Primarily carbohydrate – low in protein, minerals, vitamins
Cyanogenic glycosides must be removed before consumption
Deteriorates rapidly after harvest (worthless after 48 hours)
Cassava – Food for the “Poorest of
the Poor”
Staple food for >500 million people
Most calories per unit area of land (except for sugar cane)
Grows in poor soils
Primarily carbohydrate – low in protein, minerals, vitamins
Cyanogenic glycosides must be removed before consumption
Deteriorates rapidly after harvest (worthless after 48 hours)
Low tech crop  no profit for large companies
Starchy Root Crops – Sweet
Potato
Ipomoea batatas –
Convolvulaceae (Morning Glory
Family)
Tuesday Lecture – Stem and
Root Crops
Reading: Textbook, Chapter 7