I've found on the web a site which describes the majority of animal species. What is a site that describes most plants?

I use this site for plant research

It’s a good site, but doesn’t provide description of the plants (the cultivation, if it must be on shade or on the sun, how much water, ecc.)

You asked for a site that offers descriptions. Try Better Homes and Gardens for additional information.

^^ Cruiser beat me to it.

What you are talking about, I think, is Plant Taxanomy, or the system of naming and identifying plants for the purposes of research like you describe above in your details. But most of us don’t know the Latin taxonomic names of plants or the system of plant taxonomy, we just know their common household names, or more specifically, their LOCAL common household names, and this has hindered many from doing serious research on their plants. So we first need a reliable interpretation of the common name to the taxonomy.

Enter the Internet. This site does that and more. You punch in the common name and it will give you pictures of plants that are known by that name and their taxonomic names including descriptions and care requirements. You can even punch in your zip code for specifics on your growing area in reference to the plant in question. Here’s another site that gives good info based on common names. And here’s another. And here’s another. Just keep clicking through them and you’ll eventually find all the info you need.

Sometimes it’s really nice to live in 2016.

I have searched for Camellia sinensis and it doesn’t provide any information, save some pictures.

@luigirovatti I just ran a search on Camellia sinensis and got a hit right away using one of the above sites. Can’t do your work for ya, pal.

Forget it. Never mind.

http://www.teaflowergardens.com/growing-tea.html
http://www.kew.org/science-conservation/plants-fungi/camellia-sinensis-tea

So, that’s Chai. Wow. Welcome to Fluther, @luigirovatti.

I think you will find this chart useful. (From Scientific American March 2016 issue.)
All Known (2.3 Million) Species Are Mapped into a Single Circle of Life .

I can study that for hours!

Oy. Look at bacteria.

I went to the website that contains all the data. Incredible… Each line represents 500 species. Humans aren’t even a blip on the radar screen . We’d be at about the 8:30 position on the wheel if we measured up.
The heavier lines are species that have been DNA sequenced.