Qortin Isopo is characterised by well established vegetation communities that are closely associated with the geomorphology of the area. Garigue communities characterise the promontory’s plateau; maquis communities are present at the base of the escarpments where more shelter prevails; and garigue communities with coastal elements are present amongst the boulder screes. The garigue at il-Qortin Isopo is of high ecological and scientific importance, not only due to the presence of rare species but also due to a unique assemblage of species occurring within a dense and relatively pristine vegetation community.
Il-Qortin Isopo, and the nearby biogeographically correlated Qortin tal-Magun, constitute one of only two sites where the white rock rose (Cistus monspeliensis) occurs in the Maltese Islands, the other locality being Wied Rini in mainland Malta. Albeit rare throughout the Maltese Islands, a particularly dense population of this species is found on both promontories. The rock rose constitutes a dominant species together with the tree spurge (Euphorbia dendroides), the Mediterranean thyme (Thymus capitatus) and the shrubby kidney-vetch (Anthyllis hermanniae).
Il-Qortin Isopo promontory is bound by one of the most extensive stretches of boulder screes in the Maltese Islands, known as Irdum il-Kbir, which support pockets of maquis and garigue communities. Small permanent springs are also present within the cliff-face of Irdum il-Kbir—the only known locality in the Maltese Islands for the Bracken fern (Pteridium aquilinum).
MEPA scheduled the geomorphological features and the associated floral assemblages of Il-Qortin Isopo, Il-Qortin tal-Magun as a Level 1 Area of Ecological Importance and a Level 1 Site of Scientific Importance as per Government Notice No. 712/06 in the Government Gazette dated 11 August 2006.