Cây này có độc.

• cây = tree or plant
• này = this
• có = to have
• độc = poison, poisonous, or toxic depending on context

So the sentence is literally This plant has poison, which is why the natural English meaning is This plant/tree is poisonous.

Here, cây is the noun itself, meaning tree or plant.

Vietnamese also uses cây as a classifier in phrases like cây bút (a pen), but that is a different structure. In Cây này có độc, there is no second noun after cây, so it is not a separate classifier here.

Vietnamese words often cover a broader range than a single English word. Cây can refer to:

• a tree
• a plant
• sometimes even a shrub or similar growing thing

So the exact English translation depends on context. If you are pointing at a large woody plant, tree is natural. If the context is more general, plant may be better.

Because Vietnamese demonstratives usually come after the noun.

So:

• cây này = this tree/plant
• cây kia = that tree/plant

English says this tree, but Vietnamese says something more like tree this.

Có độc literally means has poison. This is a very natural Vietnamese way to express the idea is poisonous or is toxic.

Vietnamese does not always match English word-for-word. Where English uses be + adjective, Vietnamese may use a phrase like:

• có độc = has poison → is poisonous
• có hại = has harm → is harmful

So even though the literal wording is different, the meaning is completely natural in Vietnamese.

Sometimes yes, but Cây này có độc is clearer for a learner and very natural.

Why?

• độc by itself can mean poisonous/toxic
• but độc can also have other meanings in Vietnamese in other contexts, such as single, unique, or part of other expressions

So có độc makes it very clear that you mean poisonous. It is a good, safe choice.

No. Là is not used here.

In this sentence, có độc is already the predicate, so Cây này có độc is complete by itself.

A sentence like Cây này là có độc would sound unnatural. Vietnamese often does not use a direct equivalent of English to be in sentences like this.

A rough pronunciation guide is:

• cây: starts with a hard k sound; level tone
• này: similar to nye; falling tone
• có: like koh; rising tone
• độc: ends with a short clipped -k sound; heavy low tone

Tone pattern:

• cây = level
• này = falling
• có = rising
• độc = low, heavy, abrupt

English-style approximations are only rough, so it is best to listen to native audio if possible.

Here it means poisonous or more generally toxic.

For a plant, poisonous is the natural English translation.
If you want to talk about an animal that injects venom, Vietnamese often uses nọc độc:

• con rắn có nọc độc = a venomous snake

So in Cây này có độc, the idea is simply that the plant is toxic/poisonous.

You can say:

• Cây này không có độc. = This plant is not poisonous.
• Cây này có độc không? = Is this plant poisonous?

That last pattern, ... không?, is a very common way to make a yes/no question in Vietnamese.