But have you ever seen a tree with a big, twisted knot growing out of it?

但你有否見過在一棵樹上生長出一個大的、扭曲的結節？

You know what that is?

你知不知道它是甚麼？

Plant cancer.

植物癌症。

It’s not super easy to define what cancer is. But in humans, cancer is often described as

癌症並不容易被界定。但在人類中，癌症通常被描述成

uncontrolled cell division that can spread into surrounding tissues, forming a tumor.

由不受控制的細胞分裂，擴散到周圍組織，從而形成了腫瘤。

And the plants can get their own version of a tumor.

植物也有自己患腫瘤的方式。

It’s just much harder for it to spread, because of how plants are structured.

但是因為構造的關係，腫瘤較難在植物體內擴散。

Still, plant cancer can be harmful, sometimes even fatal.

儘管如此，植物癌症也可以是有害的，有時甚至是致命的。

Cancer often -- but not always --

癌症經常 - 但並非總是如此 -

starts in humans or other animals because of mutations in a cell’s DNA that mess with the normal cellular growth cycle.

在人類或其他動物體內發生，因為細胞中的DNA搗亂正常的細胞生長週期。

A healthy cell will stop dividing when the area around it starts getting crowded,

一個健康的細胞會在它周圍的區域開始變得擁擠時停止分裂，

but cancer cells just keep dividing over and over, no matter how little room there is.

但癌细胞只是不停地分裂，不管還有沒有空間。

In plants, a cell can keep dividing, too, not because of genetics,

對植物而言，細胞是可以不斷分裂的，但並不是因為遺傳的關係，

but because of other factors, like an infection or some kind of structural damage.

而是由於其它因素，如感染或某種結構的損壞。

The main advantage that plants have here, though,

植物具有其中一個主要的優點就是：

is that it’s a lot harder for this uncontrolled cell division to spread to other areas.

這種不受控制的細胞要分裂蔓延到其他地區是很困難的。

In animals, cancerous cells invade other types of tissue by circulating around in the blood.

在動物中，癌細胞在血液中循環，容易侵入周圍其他類型的組織。

But plants don’t have true circulatory systems, and the fluids they use for nutrient transport,

但植物沒有真正的循環系統，即使他們有通過液體運送，

like sap, don’t have cells in them.

如細胞液，裡頭卻沒有細胞只有液體。

And there’s another factor keeping cancerous plant cells in place: the cell wall,

還有保持癌植物細胞在同一位置的另一個因素是：細胞壁，

a rigid structure that surrounds the outside of the cell and helps the plant stay upright.

一個包圍在細胞外的堅硬物質，這種物質也有助於植物保持直立。

Those firm cell walls prevent cells from moving around within the plant. So even if it wanted to,

這些堅定的細胞壁阻止細胞在植物中四處移動。因此，即使它想，

a cancerous cell couldn’t break off from a tumor and go spread to other tissues.

癌細胞也無法從一個腫瘤中脫落並進入及擴散到其他組織。

It’s trapped.

它被困住了。

Instead, these cells keep dividing in place, over and over again.

相反，這些癌細胞會在同一地方不斷分裂，一遍又一遍。

That’s what forms growths like those funky knots on trees --

這些增生就是形成像樹木那些古怪結節的原因，

which are called galls or burls.

它們被稱為癭瘤或樹瘤。

Since the out-of-control cells are kept so firmly in place,

由於那些超出控制的癌細胞如此堅定地保持在同一地方，

the plant is usually able to live out its life with these growths just fine.

植物通常能夠與這些增生共存。

But sometimes, they will overwhelm it, and the plant can eventually die.

但有些時候，那些增生會壓倒它，植物最終可能會死亡。

So, sadly, plants do get cancer, too, in a way.

所以，可悲的是，植物也會得癌症，只是和動物的形式不同。

It’s just different because they’re plants.

不同之處只是他們是植物而已。

Thanks for asking! And did you know that SciShow is now on Patreon?

謝謝你的題問！而且你知道嗎，現在SciShow現在正接受贊助！

If you want to keep getting answers to questions like this, you can go to Patreon.com/SciShow

如果你想繼續得到類似這些問題的答案，你可以上Patreon.com/SciShow

to learn how you can support us by becoming a SciShow Patron!

了解如何通過成為SciShow Patreon的一員來支持我們！