Article: The Jordan River runs along the Jordan Rift Valley, from Mount Hermon through the Hulah Valley and the Sea of Galilee to the Dead Sea, the lowest point on the surface of the Earth. Further south is the Arabah, ending with the Gulf of Eilat, part of the Red Sea. Unique to Israel and the Sinai Peninsula are makhteshim, or erosion cirques. The largest makhtesh in the world is Ramon Crater in the Negev, which measures 40 by 8 kilometers (25 by 5 mi). A report on the environmental status of the Mediterranean basin states that Israel has the largest number of plant species per square meter of all the countries in the basin.

Now answer this question: Israel has the largest number of what per square meter in the basin?
plant species