etymology of tree name "maraam" and the geography of the maraam t ree

[Chandrasekaran, Periannan]

Could someone provide the etymology of the word "maraam"
used very frequently in Tamil Sangam era literature
to denote the tree called "katampu" or "veN (white) katampu"?
It also seems to be referred to as "aachchaa" tree.
I do not have the English name with me. It is said to have
white flowers.
A handful of Tamil Gods favor this tree.
Murukan especially favors that tree, its flowers,
and marram forests. Thirumaal (related to VishNu)is also
said to favor this tree. From Tamil literature one gets
the impression that this tree was (or still is?) thriving
in Tamil Nadu.
The ancient poets also liked it so much that in ancient Tamil literature
that it has
formulaic poetic version too  which is "maraaam";
 note the *three* "a"s; this is so as to conform to the
meters employed in Tamil, undoubtedly the most sophisticated
in any language, the already long vowel "aa" was lengthened
one more unit of time.

Does it grow in North India?

Thanks
P. Chandrasekaran