Shulchan Aruch and Rama, Orech Chaim 297:4
1 א
שולחן ערוך אורח חיים סימן רצז סעיף ד
נהגו לברך על ההדס כל היכא דאפשר. הגה: וי"א דאין לברך על הדס היבש דאינו מריח, רק על שאר בשמים, וכן נהגו במדינות אלו. ונ"ל דיש להניח גם הדס עם הבשמים, דאז עושין ככ"ע
It is the accepted practice to recite the blessing [over spices in havdallah] over a myrtle branch wherever this is possible. Gloss of the Rama: Some authorities say that a blessing should not be made over a dry myrtle-branch, which does not emit odor, but rather over other spices; and so is the practice in these provinces. It appears to me that the myrtle-branch should be put together with the other spices, for then all views will have been satisfied. [Translated by Rabbi Aviel Orenstein]
3 ג

Suggested Discussion Questions:

How many blessings can you think of that relate to things found in nature?

What is the significance of this multitude of blessings about the natural world?

4 ד
Time Period: Medieval (Geonim through the 16th Century)