Questions & Answers about La orquídea tiene dos flores.
Because la orquídea means the orchid: a specific orchid, not just any orchid.
In Spanish, a singular countable noun like orquídea normally needs an article or another determiner in this kind of sentence:
So Orquídea tiene dos flores would sound incomplete or wrong in normal Spanish, unless Orquídea were a person’s name.
Because orquídea is a feminine noun in Spanish, so it takes la in the singular:
- la orquídea
- las orquídeas
This is grammatical gender, not biological sex. Even though it is a plant, the noun itself is treated as feminine.