分佈欖仁樹常生於氣候溫熱的海邊沙灘或向陽處山坡草地上，現常栽培作行道樹。原產於台灣、海南島[8]、馬來西亞印度及太平洋諸島 。在中國境內，分佈於廣東、四川 、湖北 、雲南東南部。於越南、 大洋洲、及南美熱帶海岸等地均有分佈。
生長欖仁樹喜生長於高溫濕潤的氣候，光線充足的環境，不拘土質，但種植於肥沃排水良好的砂質土壤中最佳，能耐旱抗風耐鹽性強。主要使用播種方式繁殖[12]。同時果實能浮於水面，故亦具有海漂植物散佈的特性。
形態特徵
欖仁樹的果實欖仁樹是一種落葉喬木，高可達15米或更高。樹皮縱裂呈剝落狀，褐黑色。枝幹平展，側枝輪生，近頂端密披黃色絨毛，落葉後有密而明顯的葉痕，樹冠層傘形，老樹有明顯板根。葉倒卵形，互生，叢生枝頂層次分明，基部截形或狹心形，先端鈍圓或短尖，中部以下漸狹，全緣，葉兩面無毛或幼時背部披疏軟毛，葉基背偶有一對腺體[8][15]，主脈粗壯，表面下陷形成一淺槽，背面凸起，基部葉柄處披絨毛，側脈10－12對，網脈稠密，長約12－22厘米，寬約8－15厘米；葉柄披毛，短而粗壯，長約10－15毫米；秋季轉紅葉，冬季落葉[4][14]。花為穗狀花序長而纖細，腋生，雌雄異花植物[1]，雄花長於上部，雌花或兩性花長於下部[12][1]，長約15－20厘米；花多數，綠色或白色，長約10毫米；花盤由5個腺體組成，披白色粗毛；花苞片小，早落；缺乏花瓣[14]；花萼筒杯狀，外面無毛，內面披白色柔毛，長約8毫米；萼齒5裂，白色[12]，三角形，幾乎與萼筒等長；雄蕊10枚，伸出花萼之外，長約2.5毫米；子房呈圓錐形，幼時披毛，成熟時近無毛；花柱粗壯，胚球2顆，倒懸於室頂。果為核果，扁橢圓形，兩端稍漸尖，兩邊具梭，梭上具翅狀的狹邊像船隻的龍骨狀構造；果皮無毛含纖維質，堅硬，初為綠色，成熟時呈咖啡色，內果皮堅硬而質輕，能浮於水面，長約3－4.5厘米，寬約2.5－3.1厘米。種子矩圓形，1顆，含油質
藥性及用途 維基百科的醫學類別條目僅供參考，並不能視作醫療意見。
任何健康問題應諮詢專業的醫護人員。
欖仁樹的樹皮性味苦、性涼，有收斂之效，對解毒止瘀、化痰止咳、痢疾、痰熱咳嗽及瘡瘍有治療功效。葉及嫩葉對疝痛、頭痛、發熱、風濕關節炎有治療功效。葉汁對皮膚病、痲瘋及疥癬有治療功效。種子性味苦、澀、性涼，可清熱解毒，對咽喉腫痛、痢疾及腫毒有治療功效。
欖仁樹的種子含油份，油份芳香含杏仁味，可供製成食品添加調味料[6]及藥用[4]；果皮含鞣質，可製成黑色染料；果皮、成葉及落葉均可染出黃褐與綠褐色系；而樹皮亦含有單寧成份，可製成黑色染料；木材可作船隻及家具等的用材。
Terminalia catappa is a large tropical tree in the Leadwood tree family, Combretaceae. The tree has been spread widely by humans and the native range is uncertain. It has long been naturalised in a broad belt extending from Africa to Northern Australia and New Guinea through Southeast Asia and Micronesia into the Indian Subcontinent. More recently the plant has been introduced to parts of the Americas.
It grows to 35 metres (115 ft) tall, with an upright, symmetrical crown and horizontal branches. The Terminalia catappa has corky, light fruit that is dispersed by water. The nut within the fruit is edible when fully ripe,tasting almost like almond. As the tree gets older, its crown becomes more flattened to form a spreading, vase shape. Its branches are distinctively arranged in tiers. The leaves are large, 15–25 centimetres (5.9–9.8 in) long and 10–14 centimetres (3.9–5.5 in) broad, ovoid, glossy dark green and leathery. They are dry-season deciduous; before falling, they turn pinkish-reddish or yellow-brown, due to pigments such as violaxanthin, lutein, and zeaxanthin.
The flowers are monoecious, with distinct male and female flowers on the same tree. Both are 1 centimetre (0.39 in) in diameter, white to greenish, inconspicuous with no petals; they are produced on axillary or terminal spikes. The fruit is a drupe 5–7 centimetres (2.0–2.8 in) long and 3–5.5 centimetres (1.2–2.2 in) broad, green at first, then yellow and finally red when ripe, containing a single seed.
Cultivation and uses
Terminalia catappa is widely grown in tropical regions of the world as an ornamental tree, grown for the deep shade its large leaves provide. The fruit is edible, tasting slightly acidic.
The wood is red, solid and has high water resistance; it has been utilized in Polynesia for making canoes. In Telugu it is known as "Badam Chettu".
The leaves contain several flavonoids (like kaempferol or quercetin), several tannins (such as punicalin, punicalagin or tercatin), saponines and phytosterols. Due to this chemical richness, the leaves (and also the bark) are used in different traditional medicines for various purposes. For instances, in Taiwan fallen leaves are used as a herb to treat liver diseases. In Suriname, a tea made from the leaves is prescribed against dysentery and diarrhea. It is also thought that the leaves contain agents for prevention of cancers (although they have no demonstrated anticarcinogenic properties) and antioxidant as well as anticlastogenic characteristics.
Keeping the leaves in an aquarium is said to lower the pH and heavy metal content of the water[citation needed]. It has been utilized in this way by Betta breeders in Thailand for many years. It's also believed that it helps prevent fungus forming on the eggs of the fish.[citation needed]. Local hobbyists also use it for conditioning the betta's water for breeding and hardening of the scales.
