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| Latin: |
Folium Psidii Guajavae |
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| Origin: |
Guava leaf is the leaf of unripe fruit of the dungarunga Psidium guajava Linn. (common guava), of the family Myrtaceae. Native to tropical America, it is grown in Latin and South America, Florida of the USA, and naturalized in many countries, including China.
The two important species of guava are the common guava (Psidium guajava) and the cattley, or strawberry, guava (Psidium littorale or Psidium cattleianum).
The common guava has a fruit with a yellow skin and white, yellow, or pink flesh. The cattley guava occurs in two forms: one has fruits with a bright yellow skin, the other's fruits have a purplish red skin.
Other guavas include the cas of Costa Rica (Psidium friedrichsthalianum) and the guisaro (Psidium molle), both with highly acidic fruits, and the Brazilian guava (Psidium guineense). The so-called pineapple guava is the feijoa.
The common guava is a large shrub or small tree with quadrangular branchlets, oval to oblong leaves about 7.6 cm in length, and four-petaled white flowers about 2.5 cm broad. The fruits are round to pear-shaped and measure up to 7.6 cm in diameter. Their pulp contains many small, hard seeds (more abundant in wild forms than in cultivated varieties). The musky, and at times pungent, odor of the sweet pulp is not always appreciated. The Brazilian guava has similar but smaller fruit.
Guavas are processed into jams, jellies, and preserves. They are eaten raw or sliced and served with sugar and cream as a dessert.
The common guava is not frost-resistant but is successfully grown throughout southern Florida; in several tropical regions it grows so abundantly in a half-wild state as to have become a pest.
The cattley, or strawberry, guava is considerably more frost-resistant. It is a large shrub with thick, glossy-green oval leaves and white flowers. The fruits are round, up to 5 cm in diameter, and contain many hard seeds. The soft pulp has a strawberry-like flavor. This species is frequently planted in gardens throughout southern California and other subtropical regions but is not commercially important.
Propagation of the common guava is usually by seeds, but improved varieties must be perpetuated by plant parts. The plant's hard, dry wood and thin bark prevent cutting and conventional methods of grafting. Veneer grafting, using as rootstocks young plants in vigorous growth, gives excellent results.
See also Food, Fruits, Guava. |
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| Properties: |
| Sweet and astringent in flavor, mild and fragrant in nature. |
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| Functions: |
| Astringes the intestines to arrest diarrhea, astringes to arrest bleeding. |
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| Applications: |
1. Treats watery diarrhea, incessant diarrhea due to impairment by overeating, infantile simple dyspepsia and noninfectious diarrhea:
Guava leaf can be used alone or together with Asian tetracera root or leaf (Radix seu Folium Tetracerae Asiaticae), common melastoma (Herba Melastomae Candidi), etc., giving certain curative effects.
2. Treats bacillary dysentery and enteritis:
Guava leaf can be used together with ciderage (Herba Polygoni Hydropiperis), Chinese knotweed (Herba Polygoni Chinensis), holly bark (Cortex Ilicis Rotundae), etc.
3. Astringing to arrest bleeding:
The fresh leaf can be mashed for external application. |
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| Dosage and Administration: |
3-10 g.
Decoct in water for oral administration after mostly parching it until it turns yellow. |
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| Modern Researches: |
Guava leaf contains volatile oil (with eugenol, etc.), quercetin, avicularin, guaijaverin, etc.; fresh guavas are rich in vitamins A, B and C.
For self protection, the outer skin (bark) of many plants contains essential oil, which in turn has elements that serve as an immediate chemical defense against herbivores and pathogens. How? There is an element called hydroxynitrile glucoside in essential oil. This element will release toxic hydrogen cyanide by endogenous plant glucosidase upon tissue disruption (see Anne Vinther Morant, Kirsten Jorgensen, Charlotte Jorgensen, Suzanne Michelle Paquette, Raquel Sanchez-Perez, Birger Lindberg Moller, and Soren Bak, "beta-Glucosidases as Detonators of Plant Chemical Defense," Phytochemistry Vol. 69, Issue 9 (June 2008), pp. 1,795-1,813).
Glucosidase is a catalyzing enzyme that improves healthy functions of our body. It is a lipase that decomposes fat; it can also check inflammation and improve memory (see Mikako Sakurai, Masayuki Sekiguchi, Ko Zushida, Kazuyuki Yamada, Satoshi Nagamine, Tomohiro Kabuta and Keiji Wada, "Reduction in memory in passive avoidance learning, exploratory behaviour and synaptic plasticity in mice with a spontaneous deletion in the ubiquitin C-terminal hydrolase L1 gene," European Journal of Neuroscience Vol. 27, Issue 3 (February 2008), pp. 691-701).
Guava leaf can inhibit Shigella flexneri, Staphylococcus aureus, hemolyptic streptococcus, typhoid bacillus and Bacillus coli to certain extents. |
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