Alga apare pe planta acvatică.

In Romanian, algă is the singular noun: an alga.

• algă = an alga
• alga = the alga
• alge = algae / algae (plural)
• algele = the algae

This can feel a little tricky for English speakers because English often uses algae in general discussion, even when people are not being very precise.

Romanian usually puts the definite article at the end of the noun instead of using a separate word like English the.

So:

• algă = an alga
• alga = the alga
• plantă = a plant
• planta = the plant

That is why the sentence has alga and planta, not a separate word meaning the.

Apare is the 3rd person singular present tense of the verb a apărea.

So:

• eu apar = I appear
• tu apari = you appear
• el/ea apare = he/she/it appears

Since the subject here is singular (alga), the verb is also singular: apare.

Here apare means something like appears, shows up, or becomes visible.

So the sentence suggests that the alga is appearing on the aquatic plant, not just that it exists in general.

Depending on context, Romanian might also use other verbs for related ideas, such as crește (grows) or se găsește (is found), but apare is perfectly natural if the idea is that it shows up or becomes noticeable.

Here pe means on.

So:

• pe planta acvatică = on the aquatic plant

English speakers may also learn that pe can mark certain direct objects in Romanian, especially people, but that is not what is happening here. In this sentence, it is simply a preposition of location.

Because planta is the definite form: the plant.

Compare:

• plantă acvatică = an aquatic plant
• planta acvatică = the aquatic plant

So the sentence is using a definite noun phrase.

Because the adjective must agree with plantă/planta, which is feminine singular.

Compare:

• acvatic = masculine singular
• acvatică = feminine singular

Since plantă is feminine, Romanian uses acvatică.

Not in this kind of structure. In planta acvatică, the definiteness is shown on the noun planta, and the adjective simply agrees with the noun in gender and number.

So the whole phrase means the aquatic plant, even though the adjective itself is not carrying a separate the ending.

The given order is the most neutral one:

Alga apare pe planta acvatică.

Romanian word order is fairly flexible, though. For emphasis, you could also say:

Pe planta acvatică apare alga.

That puts more focus on where the alga appears. But the original version is the most straightforward for a learner.

A simple pronunciation guide is:

AL-ga a-PA-re pe PLAN-ta ak-VA-ti-kə

A few useful points:

• g in alga is a hard g
• c in acvatică is a hard k
• ă sounds like the weak vowel in English sofa
• Romanian r is usually tapped or lightly rolled

Yes, they do.

In the sentence, the important one is:

• acvatică

And if you look at the indefinite forms, you also get:

• algă
• plantă

Romanian diacritics are part of correct spelling and often help show the correct pronunciation. So it is best to learn them from the beginning.