Department of Cell Biology & Molecular Genetics
Grasses, Legumes, and Starchy Staples
GRASSES
I. Importance
A. Ecologically, where
are the grasses found?
B. Grasses include the
cereal crops
1. in terms of feeding people, they are the most important group of plants
in the world.
2. food for farm animals
C. Three most economically
important cereal crops: Wheat, Rice, and Corn.
D. All grasses are monocots.
E. Reproductive features
1. the flower is called an inflorescence. Can have perfect
or imperfect flowers. Wind pollination.
2. the fruit is called a caryopsis or grain. What are the parts of
a grain? Do the parts vary in terms of nutritional value?
F. What are the advantages
of having grain as food?
II. Wheat (Triticum sp.)
A. Origin: The Near East
(Fertile Crescent)
B. Domestication of wheat
resulted in the three kinds we have today:
1. Einkorn wheat is diploid (AA). Medium grain size and non-shattering.
2. Emmer and Durum wheat are tetraploid (AABB). Large grain size
and non-shattering.
3. Bread wheat is hexaploid (AABBDD). Extra large grain size and
non-shattering.
C. Uses of Modern wheat
III. Corn (Zea mays)
A. Origin: Central America
and Mexico
1. Evolved from teosinte
2. Domestication resulted in large cob size, an increase in the number
of kernels per cob, and non-shattering cobs.
B. Reproductive structures:
tassels and ears.
C. Uses of corn
D. Types: popcorn, flour
corn, dent corn, sweet corn.
IV. Rice (Oryza sativa)
A. Origin: Southeast
Asia
B. Cultivation: rice
paddies, flooded fields or dry upland rice.
1. flooded rice paddies: nitrogen fixation by cyanobacteria living inside
Azolla (a water fern).
C. Uses of rice
V. Other grains
LEGUMES: peas, beans, soybeans, clover, alfalfa,
peanuts
I. Importance
A. Nitrogen fixation.
B. Major sources of protein
and oil.
II. Reproductive characteristics
A. Flowers: irregular
shape, bilaterally symmetrical
B. Fruit = pod or legume.
III. Beans: red kidney bean, black bean, pinto
beans, green bean.
A. Origin: Central America
and Mexico
B. High in protein, few
carbohydrates. Digestive problems (raw or cooked beans), causes gas
due to carbohydrates.
IV. Peas: garden pea
A. Origin: The Near East
(Fertile Crescent).
B. High in protein, few
carbohydrates.
C. The subject of Mendel’s
investigations of genetics.
V. Peanut
A. Origin: South America
B. High in oil and protein
(has the HIGHEST protein content compared to all the other legumes)
VI. Soybean
A. Origin: China.
B. Oil has both food
and industrial uses
C. High in protein
VII. Foraging legumes: food for grazing animals:
alfalfa, clover, vetch
STARCHY STAPLES
I. Importance
A. Starchy crops have
storage organs that store large amounts of starch
II. White potato: tuber
A. Origin: South American
Andean highlands.
B. 25% carbohydrate,
2.5% protein (but well balanced amino acid content)
III. Sweet potato: tuberous root
A. Origin: Central America
and Mexico.
B. Orange cultivars also
rich in Vitamin A and beta-carotene.
IV. Cassava: tuberous root
A. Origin: Brazil
B. Careful processing
required to remove hydrogen cyanide (HCN)
C. Has the HIGHEST starch
content compared to all the other starchy crops
V. Other starchy crops:
A. Yam: tuber
B. Taro: a corm
C. Plantain has more
starch than regular bananas. Regular bananas also have starch, but
are much sweeter.
A few exam #3 practice questions:
1. Which one of the following is currently
believed to be the ancestor of modern corn?
A. triticale
B. rice
C. teosinte
D. popcorn
2. Which one the following has the highest
protein content?
A. potato
B. wheat
C. peanut
D. rice
3. Nitrogen fixating bacteria would most
likely be found on the roots of which of the following plants?
A. soybean
B. barley
C. potato
D. wheat