Comment: I think that translating "cha" as "tea" while 100% right for
general purposes, for people deeply interested in tea certain notes should
be added. The full and precise meaning of "Cha" is "steeped drink".
Although
99% of the time it is made of C. sinensis, many other plants can be used.
Translating it to English "tea" is still the best because in English "tea"
can also be non-C. sinensis (Camomille tea, etc.).
Addition: There is a Chinese character that means :leaves of C.
sinensis" -
its ming2. It combines normal character ming - "name" with grass radical
(same as on the top of "cha"). Unicode index U+8317.


Just a few remarks: The character "cha2" seems to be the graphical evolution
of "tu2", a character that was used in ancient times to indicate a kind of
"bitter vegetable". "Cha2" in its present shape, came in to use only in the
Tang dynasty (8th century), with the composition of "Chajing" by Lu Yu, but
it seems that the character "tu2" was already pronunced "cha2" when used to
indicate C. sinensis in order to distinguis it from other "bitter plants".
Regard to "ming2", ancient lexicographical dictionaries define it as "buds
of tu2", which seems to confirm the identification of "tu2" with tea.
It would also be useful to remind that tea was boiled and not steeped by the
time the character "cha2" came in to use.
Apart its historical development, the Chinese character "cha2", as its
equivalent English word "tea", indicates basically three things: a plant,
the dried leaves of this plant and the beverage prepared with these leaves.
As a plant "cha2" indicates solely C. sinensis. If followed by the term
"shu3" (genus), it indicates the whole genus Camellia, out of which C.
sinensis is the only "drinkable" specie. As dry leaves and beverage it
indicates mainly the leaves of C. sinensis and the beverage prepared with
them. It can also be used for the leaves of other plants used for preparing
drinks, but always preceded by the name of the plant: e.g. juhua cha
(Chrisantemun flowers tea), xingren cha (almond porridge), kuding cha
(beverage made with Ilex kudingcha).