In the published Silmarillion, there's no hint as to the length of the Years of the Trees (except a rather vague reference to 'long ages' in chapter 3). However, a document does exist that gives more precise measurements, The Annals of Aman in volume X of The History of Middle-earth. That is the source of the precise figure of 14,325 years, though it's important to be aware that this unpublished figure was subjected to extensive editing, and should not be considered completely reliable.
2
Two other, less certainly canonical, names are also recorded for this Tree. Its name translated into Old English as Goldléoþ ('Gold-song'), while in the language of the Valar themselves it was said to have been called Tulukhedelgorús. (These names come from volumes IV and IX of The History of Middle-earth, respectively.)