The following sections of this BookRags Literature Study Guide is offprint from Gale's For Students Series: Presenting Analysis, Context, and Criticism on Commonly Studied Works: Introduction, Author Biography, Plot Summary, Characters, Themes, Style, Historical Context, Critical Overview, Criticism and Critical Essays, Media Adaptations, Topics for Further Study, Compare & Contrast, What Do I Read Next?, For Further Study, and Sources.
(c)1998-2002; (c)2002 by Gale. Gale is an imprint of The Gale Group, Inc., a division of Thomson Learning, Inc. Gale and Design and Thomson Learning are trademarks used herein under license.
The following sections, if they exist, are offprint from Beacham's Encyclopedia of Popular Fiction: "Social Concerns", "Thematic Overview", "Techniques", "Literary Precedents", "Key Questions", "Related Titles", "Adaptations", "Related Web Sites". (c)1994-2005, by Walton Beacham.
The following sections, if they exist, are offprint from Beacham's Guide to Literature for Young Adults: "About the Author", "Overview", "Setting", "Literary Qualities", "Social Sensitivity", "Topics for Discussion", "Ideas for Reports and Papers". (c)1994-2005, by Walton Beacham.
All other sections in this Literature Study Guide are owned and copyrighted by BookRags, Inc.
Halophytes (salt plants) are organisms that require elevated amounts of sodium up to or exceeding seawater strength (approximately 33 parts of sodium per thousand) for optimal growth. In contrast, most crops cease to produce with sodium at 1 to 3 ppt. Halophytes are found worldwide, including in deserts where infrequent rainfall leaches ions to the surface. They encroach into irrigated lands as ion concentrations increase over time. They are best known as mangroves, a term for a number of unrelated tree species, which in tropical ecosystems stabilize coastlines in species-rich habitats threatened by development. Halophytism characterizes species in many plant families, indicating adaptive evolution from nontolerant ancestors. Typical adaptations are succulence, water-conserving mechanisms, and specialized surface morphology (e.g., trichomes and waxes). Resistance to salinity is costly, explaining the slow growth of halophytes. Energy expenditure for ion pumping is required for sodium export (from glands), partitioning (movement of sodium away from growing tissues) or storage (in vacuoles, specialized cells, or senescing leaves). Another source of energy expenditure is for absorption of essential ions and nutrients from the soil. This active transport process is made more difficult by high levels of sodium in the surrounding soil. Valued for their ecological importance, few halophytes are economically significant, while species such as Salicornia have potential utility as oil crops.
Coastal Ecosystems; Deserts; Trichomes.
National Research Council. Saline Agriculture: Salt-Tolerant Plants for Developing Countries. Washington, DC: National Academy Press, 1990.
Ungar, I. A. Ecophysiology of Vascular Halophytes. Boca Raton, FL: CRC Press, 1991.