23/10/2026
【標本秀 Specimen Showcase｜黑暗殺手？綠色巨人？是你那不為人知的鄰居！A dark assassin? A green giant? It’s your mysterious neighbor! 】*Eng below*
漫步在香港任何一條街道上 🏢，你都會看見這些高聳的綠色巨人——枝間垂掛著層層疊疊的「棕色絲簾」，下方有多重「樹幹」並立，龐大的樹冠在石屎森林中，為繁忙的行人路灑下大片令人心曠神怡的綠蔭。走近細看，你可能會察覺一絲古怪：那些「樹幹」也許全都來自同一株植物。數十條氣生根與一根主幹，共同撐起一片廣闊的樹冠，讓一棵樹看起來就像一片微型森林。🌳這就是細葉榕（𝘍𝘪𝘤𝘶𝘴 𝘮𝘪𝘤𝘳𝘰𝘤𝘢𝘳𝘱𝘢 L.f., 1782），香港最常見的樹木之一。但在它那平和、蔭涼的外表之下，卻藏著大自然最狡黠的生存故事之一——一個關於欺騙、慢性謀殺，以及一段延續了數百萬年的秘密聯盟關係的故事。
細葉榕是一種原生於熱帶亞洲的常綠喬木。它可以長到25米高，樹冠寬闊得足以遮蔽一整棟房屋。葉片呈革質、深綠而富有光澤，乍看之下並不起眼🍃；真正別具特色的，是它的氣生根（aerial roots）。成熟的細葉榕會長出鏽褐色的氣生根，像一道道棕色絲簾從枝幹垂落。這些氣生根觸及地面，便會逐漸增粗、木質化，形成具有支撐作用的支柱根（prop roots）。隨着時間過去，支柱根可長成粗壯的柱狀結構，外形猶如樹幹🪵。每一根新「樹幹」仍是原來那棵樹的一部分，讓細葉榕得以向外擴展，獲取到更多陽光，並在崎嶇或傾斜的地面上站穩腳跟。在擁擠的森林和城市街道中，這種生長方式使細葉榕能夠佔據那些單靠一根樹幹難以伸展至的空間，爭取更多光照。因此， 一棵細葉榕便可長出數十根樹幹般的支柱，營造出獨木成林的景象，同時也為昆蟲、鳥類及小型植物提供蔭涼的微生境。
然而，常常在你余光中街角處被略過的，並不只是單單一棵樹，而更是一座建立在契約之上的秘密堡壘：只對一位神秘貴賓開放。細葉榕會開出微小的花，但從外面卻看不見，因為花朵全都藏在一個看起來像果實的結構裡：榕果（與可食用的無花果為不同物種的同類構造）🍏。每顆榕果就像一間密室，頂端只有一個稱為「孔口」的微小開口。數百朵小花藏身其中，静静等待，與外界隔絕。而讓人驚歎的是，這些花無法通過風或其他昆蟲傳粉，它們只能依賴一個物種——細葉榕傳粉榕小蜂，𝘌𝘶𝘱𝘳𝘪𝘴𝘵𝘪𝘯𝘢 𝘷𝘦𝘳𝘵𝘪𝘤𝘪𝘭𝘭𝘢𝘵𝘢（Waterson, 1921）🐝。
細葉榕與榕小蜂之間究竟訂下了甚麼協議？這是自然界其中一種相互依存程度極高的互利共生關係。榕果內有特殊的「癭花」（gall flowers），讓榕小蜂產卵，為牠們的後代提供完美的育嬰室 🚼。作為回報，新生的榕小蜂羽化成熟後，會帶着出生地榕果的花粉離開，再從另一顆榕果的微小孔口鑽進去。牠在榕果內爬行時為雌花授粉，然後在癭花內產卵。細葉榕因而得以結出種子，榕小蜂亦能繁衍後代，缺少任何一方，另一方都無法繁殖。兩者唇齒相依——這不是泛泛之交、普通合作，或什麼曖昧關係，而是經歷數百萬年演化形成的生死相依。事實上，細葉榕傳粉榕小蜂其實是至少三個隱存種的複合群；當細葉榕被引種到原生分佈範圍之外時，只有其中一種成功在新地區建立族群。同一項研究亦指出，這種微小的傳粉者大約在130年前，伴隨著牠龐大的共生夥伴，從熱帶原生地遷徙到了美洲及地中海地區🍃。
榕屬樹木的生命歷程，還藏着其他令人驚嘆的故事。細葉榕是一種絞殺榕︰它的生命往往不是從地面開始，而是在另一棵樹的高處枝椏間長出🌱。蝙蝠、鳥類、果子狸，甚至松鼠等動物都會吃下榕果。牠們在樹上活動時，可能透過糞便將細小的種子留在枝椏間。這小小的種子隨後在樹冠上萌芽，緩慢地向下伸出根來，朝土壤探去。隨着根部不斷生長，它們會纏繞宿主樹的樹幹，像一張逐漸收緊的網。幼小的細葉榕與宿主爭奪陽光和養分，最終可能令宿主遭「絞殺」而死。宿主其後或會逐漸腐爛，只留下細葉榕獨自矗立——一棵最初依附別的樹而生的小苗，最後竟能以巨人之姿取代宿主。這種生長方式並不局限於森林：在城市中，細葉榕亦能在建築物的牆壁和屋頂上生長 🌿。細葉榕的絞殺習性，出人意料卻又完美地適應了城市環境，讓它牢牢攀附
在人造建築的垂直表面。
在香港，最令人印象深刻的例子或許是錦田樹屋🏡。在元朗，一棵細葉榕歷經數十年的生長，逐漸吞沒了一棟荒廢的磚屋。它的枝幹與氣生根纏繞牆壁，爬過窗戶，覆蓋屋頂。這棟據信可追溯至明代（1368-1644）的房屋，如今幾乎完全被樹木包覆、吞噬。最初隨糞便落下的一顆種子，最終長成一座活生生的紀念碑——一棵「吃掉」老房子的樹。這些樹木在我們的城市中佔據一席之地，而我們亦守護着這些見證歷史、古老而雄偉的巨樹💚。我們欣賞它們的雄偉、樹蔭與美態，卻很少想到它們鮮為人知的一面——榕果裡微小的榕小蜂、對鄰近樹木的緩慢絞殺，以及它們龐大根系網絡的無聲擴張。
細葉榕有引起你對生態及生物多樣性的興趣嗎？如果你感興趣，歡迎蒞臨香港生物多樣性博物館參觀。我們展示了從珊瑚到哺乳類等各式各樣的標本，讓你深入了解這些迷人生物的生態奧秘。若你喜歡這篇文章，請與朋友分享，並密切關注我們每週推出的精彩生物多樣性故事📖！
文︰Emily
Walk through any street in Hong Kong🏢, and you will see them – towering giants with cascading “brown strings” and multiple “trunks” – their massive crowns casting refreshing shade over busy pavements in the concrete jungle. Look closer, and you might notice something strange: all the “trunks” may belong to the same plant - this is a tree that looks like a small forest all by itself, with dozens of aerial roots and a main woody stem supporting a single, sprawling canopy. 🌳This is 𝘍𝘪𝘤𝘶𝘴 𝘮𝘪𝘤𝘳𝘰𝘤𝘢𝘳𝘱𝘢 L.f., 1782, commonly known as the Chinese banyan, one of Hong Kong’s most common trees. Beneath its peaceful, shade-giving exterior lies one of nature's most cunning survival stories – a tale of deception, slow murder, and a secret alliance that has lasted for millions of years.
The Chinese banyan is a tropical evergreen tree native to much of tropical Asia. It can grow up to 25 metres tall, with a crown so wide it can shelter an entire house. Its leaves are leathery, dark green, and glossy – rather unremarkable at first glance 🍃 – yet its most distinctive feature is its aerial roots. Mature banyan trees produce rusty-coloured aerial roots that hang from the branches like brown silk curtains. When these roots reach the ground, they thicken and lignify, becoming supporting roots known as prop roots. Over time, these can grow into substantial, trunk-like pillars🪵. Each new “trunk” is part of the original tree, allowing the banyan to expand outwards, capture more sunlight, and stabilize itself on uneven or sloping ground. In crowded forests and city streets, this growth lets the banyan claim space and light that a single trunk could never reach. One tree can spread into dozens of apparent trunks, creating the illusion of a whole forest from a single individual, and forming shaded microhabitats for insects, birds, and smaller plants.
However, what you can see around the street corner is more than just a tree – it is a fortress built on a contract of exclusive entry: only one special guest is invited. The Chinese banyan produces tiny flowers, but you will never see them from the outside. They are hidden inside a structure that looks like a fruit: the fig 🍏. Each fig is a sealed chamber, with only a tiny opening at the tip called an ostiole. Inside, hundreds of tiny flowers wait, invisible to the outside world. Surprisingly, these flowers cannot be pollinated by wind or any other insects; instead, they depend on a tiny fig wasp called 𝘌𝘶𝘱𝘳𝘪𝘴𝘵𝘪𝘯𝘢 𝘷𝘦𝘳𝘵𝘪𝘤𝘪𝘭𝘭𝘢𝘵𝘢 (Waterson, 1921). 🐝
The contract between Chinese banyan and the fig wasp? That is one of the most extreme mutualisms in nature. The fig offers the fig wasp a place to lay its eggs – special "gall flowers" that provide the perfect nursery for the wasp's offspring🚼. In return, the newly emerged little insects exit their natal fig after maturation, and enter another fig through the tiny opening, carrying pollen from the fig where it was born. It pollinates the female flowers as it crawls inside, then lays its eggs in the gall flowers. The fig gets to produce seeds; the wasp gets to produce offspring. Neither can reproduce without the other. This is not a casual friendship, partnership or situationship – it is a life-or-death dependency that has evolved over millions of years. 𝘌𝘶𝘱𝘳𝘪𝘴𝘵𝘪𝘯𝘢 𝘷𝘦𝘳𝘵𝘪𝘤𝘪𝘭𝘭𝘢𝘵𝘢 is actually a complex of at least three cryptic species, and only one of them successfully colonised new regions when the banyan tree was introduced outside its native range. The same study revealed that this tiny banyan pollinator migrated from its native range to the Americas and the Mediterranean around 130 years ago, together with its massive symbiotic partner🍃.
The life cycle of Ficus trees holds other astonishing surprises. The Chinese banyan is a kind of strangler fig. Its life often begins not on the ground, but high up in the branches of another tree🌱. Figs are eaten by various animals, such as bats, birds, civets or even squirrels. The arboreal activity of these species may deposit tiny seeds in their droppings. A seed can then germinate in the canopy, slowly sending roots down towards the soil. As the roots grow, they wrap around the host tree's trunk, slowly tightening like a net. The young banyan competes for light and nutrients, potentially strangling its host tree to death. The host may eventually rot away, leaving the banyan standing alone – a tree that began life on another and ended as a giant. This behaviour is not limited to forests: in cities, banyans can grow on building walls and roofs.🌿 The banyan's strangler habit is unexpectedly well suited to gripping the vertical surfaces of human-made buildings.
Perhaps the most haunting example of this in Hong Kong is the Kam Tin Tree House 🏡. In Yuen Long, a Chinese banyan has slowly engulfed a deserted brick house over decades. Its branches and aerial roots have wrapped around the walls, creeping through windows and over the roof. The house, believed to date back to the Ming Dynasty (1368-1644), is now almost entirely consumed. What began as a seed dropped in poo became a living monument – a tree that ate a house. These trees have colonized part of our city, and we protect these ancient, majestic giants💚. We admire their size, their shade, their beauty, but we rarely think about their secret life – the tiny wasps inside their figs, the slow strangulation of their neighbours, the silent expansion of their root networks.
Does the Chinese banyan raise your interest in ecology and biodiversity? If your answer is yes, come visit us at the Hong Kong Biodiversity Museum, where we showcase a wide variety of specimens, from corals to mammals, and you can learn more about their fascinating ecology! If you find this article engaging, share it with your friends and stay tuned for our captivating biodiversity stories released weekly📖!
Text: Emily
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