Sidr is an arabic word which translates into english as 'lote'. This is a blessed tree which has been mention by Allah in the Quran, it is described as a tree of paradise. Every part of this tree is used for good health and medcinal purposes.
"And indeed he (Muhammad (peace and blessings of Allah be upon him) saw him (Jibreel) at a second descent (i.e., another time), near Sidrat al-Muntaha (the lote tree of the utmost boundary, beyond which none can pass), near it is the Paradise of Abode, when that covered the lote-tree which did cover it! The sight (of Prophet Muhammad (peace and blessings of Allah be upon him)) turned not aside (right or left), nor did it transgress beyond (the) limit (ordained for it). Indeed, he did see of the Greatest Signs of his Lord (Allah)." [al-Najm 53:13-18]