A erva daninha cobriu o caule e o ramo.

In Portuguese, many adjectives normally come after the noun. So erva daninha is the usual way to say weed or literally harmful weed/weed plant.

Putting the adjective before the noun is sometimes possible in Portuguese, but it often sounds more literary, emphatic, or changes the nuance. In this case, erva daninha is the standard expression.

Because it agrees with erva, which is a feminine singular noun.

In Portuguese, adjectives usually match the noun in:

• gender: masculine or feminine
• number: singular or plural

So:

• a erva daninha = feminine singular
• as ervas daninhas = feminine plural

Portuguese uses definite articles much more often than English.

Here:

• a erva daninha = the weed
• o caule = the stem
• o ramo = the branch

In Portuguese, it is very normal to include the article when talking about specific things, even where English might sometimes sound more natural without one.

Repeating the article before each noun is the most natural and standard option here.

So:

• o caule e o ramo sounds complete and clear.

If you leave out the second article, it may sound less natural in many contexts. Portuguese often repeats the article with coordinated nouns, especially when referring to two distinct items.

Cobriu is the pretérito perfeito do indicativo, which is usually called the preterite or simple past in English explanations.

It is the 3rd person singular form of cobrir:

• eu cobri
• tu cobriste
• ele/ela/você cobriu

Here, the subject is a erva daninha, so the verb is cobriu.

This tense usually describes a completed action in the past.

The infinitive is cobrir, meaning to cover.

A few useful forms are:

• cobrir = infinitive
• cobre = present
• cobriu = preterite
• coberto = past participle

So in this sentence, cobriu means that the action of covering was completed.

The sentence uses the most basic and common Portuguese word order:

• Subject + verb + object
• A erva daninha
  • cobriu
    • o caule e o ramo

This is the normal order and the best one for learners to use.

You could change the order in special contexts for emphasis, but that is less neutral. For example, fronting part of the sentence would sound more marked. The original version is the most straightforward.

They refer to different parts of a plant.

• caule = the main stem or stalk
• ramo = a branch or offshoot

So the sentence mentions two different plant parts, which is why both nouns are named separately.

A careful European Portuguese pronunciation would be approximately:

a ER-va da-NI-nha co-BRIU u KAU-l(ɨ) i u RA-mu

A few useful notes:

• erva: the e at the beginning is clear enough, but unstressed vowels are often reduced in European Portuguese.
• daninha: the nh sounds like the ny in canyon.
• cobriu: the stress is on the last syllable, -briu.
• caule: the au is like ow in cow.
• ramo: the final o in European Portuguese is often reduced, sounding closer to u.

Yes, Portuguese often allows the subject to be omitted if it is already clear from context. That is because the verb form gives information about the subject.

So:

• A erva daninha cobriu o caule e o ramo. = full sentence
• Cobriu o caule e o ramo. = possible if everyone already knows what did the action

However, if the subject is new information or needs to be clear, keeping A erva daninha is better.

Yes. Grammatically, that is also correct.

The difference is only the order of the two objects:

• o caule e o ramo
• o ramo e o caule

Both are possible. The original order may simply reflect what the speaker wants to mention first. There is no major grammar change.

It is both a normal noun + adjective combination and also a very common set expression.

Literally, it is:

• erva = herb/grass/plant
• daninha = harmful, noxious

But together, erva daninha is the usual way to say weed. So learners should treat it as a very common vocabulary chunk worth memorising as a whole.