She took a sample of plants in Makkah for scientific research; does she have to offer expiation?
Question

                I have done a research on plants about four years ago, when I was a university student. I took a sample of Mecca’s plants, about 3 to 5 leaves of trees located inside the haram. I did not cut a branch or anything like that. Although I know this place is sacred, I justified this by saying it is for the sake of knowledge, so it is permissible!

Please tell me if I have to expiate. How much is it and how shall it be distributed?.
Praise be to Allah.There are many ahaadeeth in
    al-Saheehayn and elsewhere which speak of the sanctity of the plants 
    of the Makkan sanctuary, for example the words of the Prophet  (peace 
    and blessings of Allaah be upon him) about Makkah: “It was not permissible 
    for anyone before me and it is not permissible for anyone after me; it was 
    only permitted to me for part of a day. Now, at this very hour, it is 
    sacred; its thorns are not to be cut, its trees are not to be cut down and 
    its lost property is not to be picked up except by the one who announces 
    it.” Narrated by al-Bukhaari (112) and Muslim (1355). 
Imam Ibn Qudaamah (may 
    Allaah have mercy on him) said in al-Mughni (3/161): The scholars are 
    unanimously agreed that it is haraam to cut the trees of the Haram, but it 
    is permissible to take idhkhir [a kind of grass] and what people plant of 
    vegetables, crops and herbs. This was narrated by Ibn al-Mundhir. End 
    quote. 
So they were unanimously 
    agreed that it is haraam to cut the trees of the Haram, but they differed 
    concerning some issues, such as: 
Is it haraam to cut 
    everything in the Haram, or does the prohibition apply only to that which 
    grows by itself? Most of the scholars say that what is haraam is that which 
    grows by itself; that which is planted by people is not haraam. 
Shaykh Ibn ‘Uthaymeen (may 
    Allaah have mercy on him) said in al-Sharh al-Mumti’ (7/218): What is 
    haraam is the plants of the Haram, not the onats of human beings. Based on 
    this, whatever has been planted by man or by his broadcasting seeds is not 
    forbidden, because it is his possession and is not attributed to the Haram, 
    rather it is attributed to its owner. End quote. 
Also: is it haraam to take 
    leaves from the trees of the Haram or not? The Hanbalis do not regard it as 
    permissible to take the leaves, unlike the majority of scholars who say that 
    it is permissible to take them, because it does not harm the tree. This is 
    the view of the three other madhhabs. Ibn Qudaamah said in al-Mughni 
    (3/170): He does not have the right to take the leaves of the trees. 
    Al-Shaafa’i said: He may take them, because (the tree) is not harmed by 
    that. ‘Ata’ used to grant a concession allowing people to take the leaves of 
    the senna plant [a plant that is used for medicinal purposes] which is used 
    as a laxative [i.e., the water in which its leaves are steeped is drunk as a 
    laxative, as it says in Taaj al-‘Aroos], but it should not be 
    uprooted. ‘Amr ibn Dinar also granted a concession concerning this. 
But the Prophet  (peace 
    and blessings of Allaah be upon him) said: “Its thorns are not to be cut and 
    its trees are not to be cut down.” Narrated by Muslim. And if it is haraam 
    to take something, every part of it is haraam, like the feathers of a bird. 
Their saying that it does 
    not harm the tree is not correct because it weakens it, and it may lead to 
    its destruction. End quote. 
Based on this, if the 
    leaves that the sister took came from a tree that was not planted by humans, 
    then taking them is something concerning which there is a difference of 
    scholarly opinion, but the majority say that it is permissible whereas the 
    Hanbalis disallow it. If there was no public need for taking them, then if 
    she took them although she could have used some other leaves instead from 
    outside the Haram, then she should pray for forgiveness and repent to 
    Allaah. If there was an educational need that would benefit the people, and 
    a tree outside the Haram would not do instead, then there is no blame in sha 
    Allaah.  
Whatever the case, there is 
    no liability and she does not have to offer expiation, because the fuqaha’ 
    who do not allow taking leaves are the Hanbalis, and they do not impose 
    liability for the trees of the Haram. This was stated in a fatwa by the 
    Scholars of the Standing Committee in which it says: 
If he destroys any of the 
    trees or plants of the Haram that belong to someone, then he must pay its 
    value to its owner, but if it does not belong to anyone, then he does not 
    have to do anything, but he should not do that deliberately, because the 
    Prophet  (peace and blessings of Allaah be upon him) forbade it. 
Fataawa al-Lajnah 
    al-Daa’imah (13/209). 
But if this tree belonged 
    to someone, there is nothing wrong with taking these leaves in sha Allaah, 
    because this is something that is usually tolerated.  
And Allaah knows best.