Cashew
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== Reproduction == | == Reproduction == | ||
| + | Cashew trees reproduce sexually with seeds. The cashew flowers are pollinated by bats and many kinds of insects, but they are also capable of self-pollination [http://www.uga.edu/fruit/cashew.html]. After pollination, the drupe requires 6 to 8 weeks to mature, with the pseudofruit developing in the last two weeks of the ripening process [http://www.nda.agric.za/docs/cashews/cashew.htm]. The cashew kernel, found inside the shell of the drupe, is the seed of the plant. When the drupe and pseudofruit are ripe, they fall off the tree together. If it lands in moist soil, the seed can germinate within a few days of falling. | ||
| - | + | Commercial growers usually grow their cashew crops from seeds. They soak the seeds in water to aid germination and plant them either in a pit at their permanent location or in a planting bag to be transplanted once they have grown large enough [http://www.nda.agric.za/docs/cashews/cashew.htm]. The seeds are planted 2 to 4 per hole, and a month is allowed for germination and growth. The weaker seedlings are then removed, leaving only the strongest one to mature [http://www.aphorticulture.com/Cashew.htm]. Seedlings grown in planting bags are transplanted after two months to their permanent location, but this must be done carefully because their roots are very sensitive [http://www.aphorticulture.com/Cashew.htm]. Since the cashew tree does not do well when it is transplanted, it is usually recommended that the trees be planted in their permanent locations, spaced 10 to 12 meters apart to allow them to fully mature [http://www.nda.agric.za/docs/cashews/cashew.htm]. For the first 3 years, the seedlings should be supported against wind, provided with adequate shade, and regularly watered to hasten growth [http://www.aphorticulture.com/Cashew.htm]. During this time, intercropping is often done with fast-growing crops such as legumes, vegetables, tobacco, chilies, cotton, or peanuts [http://www.aphorticulture.com/Cashew.htm] [http://www.hort.purdue.edu/newcrop/duke_energy/Anacardium_occidentale.html]. This allows productive use of the fields until the trees begin to bear fruit in their third year. The trees reach their maximum productivity after 10 years and continue producing fruit for the next 20 years or more [http://www.hort.purdue.edu/newcrop/duke_energy/Anacardium_occidentale.html]. A single tree can produce 200 to 300 fruits in one year [http://www.absoluteastronomy.com/topics/Cashew]. | |
== Ecology == | == Ecology == | ||
Revision as of 18:44, 16 May 2009
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| Cashew |
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| Scientific Classification |
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| Binomial Name |
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Anacardium occidentale |
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| Image Description |
Contents |
Introduction
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Obtain your taxonomy information from the U.S. Department of Agriculture.
Anatomy
The cashew is an evergreen, tropical tree that usually grows about 40 feet high [1]. The stem is short and gnarled, as are the branches. The branches spread very wide in an umbrella shape and the tree's width may equal or exceed its height. This is partly because the branches grow horizontally, becoming heavy and crooked with age until they touch the ground. Adventitious roots grow from the points where contact with the soil is made and the branches begin to grow up again in these places as if they are new stems [2]. The tree has large, leathery green leaves that grow 4 to 8 inches long and 2 to 3 inches wide [3]. The simple leaves have prominent pinnate venation, smooth margins, and are oval to elliptical in shape [4] [5].
In the dry season, flowers appear on 6 to 10 inch long panicles (clusters of racemes, which are similar to small branches) at the ends of the branches [6] [7]. Flowering occurs from August to September in Brazil, while in southern India, they appear from December to January [8]. The tiny, clustered flowers begin as green and turn yellowish pink to reddish pink, sometimes with stripes [9]. They each have five slender petals and are about 1/4 inches across [10]. Male, female, and bisexual flowers may be found growing together on the same panicle [11].
The cashew "nut" is actually a drupe and is the fruit of the tree. Its double shell has an inner and outer layer, connected by a porous layer of tissue that contains a caustic oil [12]. The outer layer of the cashew, a dry drupe, is called the exocarp, and the thick inner layer is the endocarp. The middle layer containing the toxic oil is called the mesocarp [13]. This toxic liquid is cardol, which is a urushiol (the same substance found in poison ivy) [14]. The shell also contains anacardic and other acids [15]. The acids in the cashew shell are strong enough to cause dermatitis and severe burns to the mucous membranes of the mouth and throat if ingested. Therefore, it is important that cashews be carefully shelled to prevent any of the oil from touching the seed (the nut commonly sold in stores is the seed of the drupe). The seed inside the drupe has two cotyledons, which is characteristic of dicot plants, and is white and meaty before roasting [16]. Since the cashew is technically a seed and not a nut, people with nut allergies may still be able to eat cashews [17].
Many people do not recognize the cashew nut as the fruit because of the cashew apple that develops after the drupe has grown to its full size (about 1 inch long) [18]. This apple is referred to as a pseudofruit because it is not a true fruit. It is the peduncle (stem) of the drupe. The stem enlarges and becomes pear-shaped to form the apple, which may be yellow, red, or yellow-red when ripe [19]. The skin of the cashew apple is waxy and the fruit is juicy and sweet with yellow pulp [20]. The apple is edible but must be eaten fresh because it spoils too easily to be transported, usually within a day after being picked [21]. The cashew apple requires about two months to ripen [22]. It becomes ripe at the same time as the drupe, and they both fall off the tree together [23]. The fruit is usually harvested after falling off the tree, and the apple and drupe are separated. If left on the ground in wet conditions, the nuts will germinate within 4 days unless they rot first [24].
Reproduction
Cashew trees reproduce sexually with seeds. The cashew flowers are pollinated by bats and many kinds of insects, but they are also capable of self-pollination [25]. After pollination, the drupe requires 6 to 8 weeks to mature, with the pseudofruit developing in the last two weeks of the ripening process [26]. The cashew kernel, found inside the shell of the drupe, is the seed of the plant. When the drupe and pseudofruit are ripe, they fall off the tree together. If it lands in moist soil, the seed can germinate within a few days of falling.
Commercial growers usually grow their cashew crops from seeds. They soak the seeds in water to aid germination and plant them either in a pit at their permanent location or in a planting bag to be transplanted once they have grown large enough [27]. The seeds are planted 2 to 4 per hole, and a month is allowed for germination and growth. The weaker seedlings are then removed, leaving only the strongest one to mature [28]. Seedlings grown in planting bags are transplanted after two months to their permanent location, but this must be done carefully because their roots are very sensitive [29]. Since the cashew tree does not do well when it is transplanted, it is usually recommended that the trees be planted in their permanent locations, spaced 10 to 12 meters apart to allow them to fully mature [30]. For the first 3 years, the seedlings should be supported against wind, provided with adequate shade, and regularly watered to hasten growth [31]. During this time, intercropping is often done with fast-growing crops such as legumes, vegetables, tobacco, chilies, cotton, or peanuts [32] [33]. This allows productive use of the fields until the trees begin to bear fruit in their third year. The trees reach their maximum productivity after 10 years and continue producing fruit for the next 20 years or more [34]. A single tree can produce 200 to 300 fruits in one year [35].
Ecology
Other
Gallery
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References
- Anacardium occidentale L. cashew Natural Resources Conservation Service. United States Department of Agriculture (USDA) PLANTS database. 5/11/09. accessed 5/11/09.
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- link title Author. Publisher. Date
See Also
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