The Stem Of Flowering Olant

Chemically Speaking, What Is Caffeine?

Caffeine is a plant alkaloid found not only in coffee beans but also in tea leaves and cola nuts. It works as a stimulant of the central nervous system and the respiratory system, as well as increasing heart rate and constricting blood vessels. As a stimulant, caffeine makes us more aware and alert and able to work without drowsiness. It is reported that coffee was discovered in the Near East (perhaps in Yemen) by goats, which became frisky and sleepless after eating the wild fruit. A shepherd is said to have located the shrub the goats had chewed and described it as "a shrub with leaves like laurel, flowers like jasmine, and little dark berries the chief object of the animals' nibbling."

What A re the Effects of Caffeine on the Body?

Caffeine stimulates or increases heartbeat rate, respiration, and basal metabolic rate and increases the production of stomach acid and urine. These effects translate into a stimulating "lift" that a person may feel. Generally, one feels less drowsy, less fatigued, and more alert and focused after consuming caffeine.

Wh ere Does the Word "Coffee"

Come From?

The word "coffee" is probably derived from the Arabic word "kahveh," which means "stimulating," and is thought to have been used to describe the effects of eating coffee seeds (beans).

What Does Caffeine Taste Like?

Caffeine is very bitter to the taste, as are other plant alkaloids. Caffeine is added as a flavoring agent to beverages such as root beer because it produces the sharp bitterness characteristic of the drink.

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Flowering Plants and Civilization

Awareness Box Continued

How Is Coffee Decaffeinated?

If green (unroasted) coffee beans are rinsed with hot water above 175°F, caffeine is extracted from the beans. However, in the process of removing caffeine, hot water alone is not used because it strips away too many of the essential flavors and aromatic elements contained in the beans. Along with water, a decaffeinating chemical such as methylene chloride or ethyl acetate is generally used. One common method involves placing the green beans in a rotating drum and softening them with steam for 30 minutes. They are then rinsed for approximately 10 hours with methylene chloride, which removes the caffeine from the beans. Methylene chloride containing the caffeine is drained off, and the beans are steamed a second time for 8 to 12 hours to remove any remaining methylene chloride solvent. Finally, the beans are air- or vacuum-dried to remove excess moisture before the roasting process. Most decaffeinated coffee contains less than 0.1 part per million (ppm) of residual methylene chloride, 100 times less than the maximum level of 10 ppm allowed by the U.S. Food and Drug Administration.

D. C. Scheirer

Chromosomes Lily Cell
Figure 24.27 A tiger lily flower.

drinks and medicines and is obtained from the roots of a genus of woody vines (Smilax) whose stems are often covered with prickles. The bulbs of squills are the source of a rodent poison and also of a drug used as a heart stimulant.

Meadow saffron is the source of colchicine, a drug once used to treat rheumatism and gout but now much more widely used in experimental agriculture to interfere with spindle formation in cells so that the chromosome number of plants may be artificially increased. This increasing of the chromosome number can result in larger and more vigorous varieties of plants. (Meadow saffron should not be confused with true saffron, a member of the Iris Family and the source of the world's most expensive spice and a powerful yellow dye.)

Bowstring hemps are related to the familiar, seemingly indestructible house plants called sansevierias (Fig. 24.28), which have long, narrow, stiff, upright leaves. The plants are

Sansevieria Varieties
Figure 24.28 Sansevieria plants.

cultivated in tropical Africa for their long fibers, which are used for string, rope, bowstrings, mats, and cloth. New Zealand flax, a larger plant, is grown in South America and New Zealand for similar purposes but is also widely used in ornamental plantings.

Several Aloe species produce juices used in shampoos, cosmetics, sunburn lotions, and in the treatment of burns. African Aloe species are prized as ornamentals in areas with

Stern-Jansky-Bidlack: 24. Flowering Plants and Text Introductory Plant Biology, Civilization Ninth Edition

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484 Chapter 24

Soaproot Plant
Figure 24.2Q An uprooted California soaproot plant.

milder climates. Their thick, fleshy leaves have short spines along the margins. The spines were once used for phonograph needles.

Many lily bulbs (e.g., onions and garlic) are edible, and wild lily bulbs were used for food extensively by Native Americans. Wild bulbs should no longer be eaten, however, as doing so may endanger the survival of native species. (Caution: Lily bulbs should not be confused with those of daffodils and their relatives. Daffodil and related bulbs are highly poisonous).

The California soaproot (Fig. 24.29) is confined to California and southern Oregon and was important for food to Native Americans of the region. It also had several other uses. The large bulbs are covered with coarse fibers that were removed and tied to sticks to make small brooms. The bulbs themselves produce a lather in water and were used for soap. Sometimes, numbers of bulbs were crushed and thrown in a small stream that had been dammed. Fish would be stupefied and float to the surface. The bulbs were generally eaten after being roasted in a stone-lined pit in which a fire had been made. While they were roasting, a sticky juice would ooze out. This was used for gluing feathers to arrow shafts.

A resin used in stains and varnishes exudes from the stem of dragon's blood plants. Grass trees of Australia yield resins used in sealing waxes and varnishes.

© The McGraw-Hill Companies, 2003

Wild Bamboo Plants
Figure 24.30 Bamboo orchids growing wild in Hawaii.

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