Why is the word flores feminine?
 

Hey guys. I started my Spanish studies two days ago, and I have a problem.

Masculine nouns usually end with O or E
Feminine nouns usually end with A

what I don't understand is why the flores is feminine.

thanks very much in advance

There are no scientific reasons for it, just it's an etymological issue. Grammar books explains different general rules; but, many times, the only solution consists of learning all exceptions by heart:

Mano => F
Mapa => M
Diagrama => M
Programa => M

And so on.

A pleasure.

thanks!

would it be grammatically acceptable in everyday speech to say, ' unos flores ' ?

Never. If a word is masculine, you must use masculine articles (un/unos/el/los); if it's feminine, its parallel (una/unas/la/las). Some words can present both forms according to its meaning (the article modifies the meaning). ;)

@Tal69: There are no rules for determining the gender of a noun in Spanish. What you quoted are just generalizations to make learning a bit easier, but by no means are rules and even less they are infallible, as you have already seen from Julvenzor's examples.

Also, these two generalizations involve nouns that end with a vowel, but the word "flor" ends with a consonant. And then, even though most nouns ending with "r" are masculine, "flor" is an exception.

Genders must be memorized, but the only way to get them right every time is to practice the language; over time these things come naturally. :)

And even then it's a rare one: the Latin word flos is masculine, but at some point most of the Romance languages have made their cognate words feminine. (Italian is an exception). I wonder whether it happened in Mediaevel Latin, perhaps influenced by the goddess Flora.

Por lo general...

Las palabras que suelen acabar en: a, ción, sión, tud, umbre.... son femeninos.
Las palabras que suelen acabar en: o, un consonante.... son masculinos.
Las palabras que acaban en la letra "e" pueden ser o masculinos o femeninos.

Por supuesto hay excepciones....