In botany, chlorosis is a condition in which leaves produce insufficient chlorophyll. As chlorophyll is responsible for the green color of leaves, chlorotic leaves are pale, yellow, or yellow-white. The affected plant has little or no ability to manufacture carbohydrates through photosynthesis and may die unless the cause of its chlorophyll insufficiency is treated, although some chlorotic plants, such as the albino Arabidopsis thaliana mutant ppi2, are viable if supplied with exogenous sucrose.
Chlorosis is derived from the word Chloris or from the Greek khloros meaning 'greenish-yellow', 'pale green', 'pale', 'pallid', or 'fresh'.
In viticulture, the most common symptom of poor nutrition in grapevines is the yellowing of grape leaves caused by chlorosis and the subsequent loss of chlorophyll. This is often seen in vineyard soils that are high in limestone such as the Italian wine region of Barolo in the Piedmont, the Spanish wine region of Rioja and the French wine regions of Champagne and Burgundy. In these soils the grapevine often struggles to pull sufficient levels of iron which is a needed component in the production of chlorophyll.
Hypochromic anemia is a generic term for any type of anemia in which the red blood cells (erythrocytes) are paler than normal. (Hypo- refers to less, and chromic means color.) A normal red blood cell will have an area of pallor in the center of it; it is biconcave disk shaped. In hypochromic cells, this area of central pallor is increased. This decrease in redness is due to a disproportionate reduction of red cell hemoglobin (the pigment that imparts the red color) in proportion to the volume of the cell are red blood cells will also be small (microcytic), leading to substantial overlap with the category of microcytic anemia. The most common causes of this kind of anemia are iron deficiency and thalassemia.
Hypochromic anemia was historically known as chlorosis or green sickness for the distinct skin tinge sometimes present in patients, in addition to more general symptoms such as a lack of energy, shortness of breath, dyspepsia, headaches, a capricious or scanty appetite and amenorrhea.