BSCI 124 - SECTION 2001
PLANT BIOLOGY FOR NON-SCIENCE MAJORS

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