Cal Madow is the last cloud forest in Somalia, and it lives on water taken out of the sea. Limestone climbs from the Gulf of Aden shore to around 2,400 metres, and all winter the northeast monsoon pushes damp air onto that north-facing wall until it cools into cloud. Behind the old port of Maydh the wall collects some 700 millimetres a year. The plain underneath gets less than 200, and on the days without rain fog makes up the difference. That moisture keeps alive old-growth African juniper, slow and gnarled, along with boxwood and tree aloes. Something like a thousand plant species grow here, two hundred of them found nowhere else. One is an aloe that turned into a tree. Aloe eminens climbs to eighteen metres and raises red flowers clear above the forest.
The road north from Erigavo drops into Daallo, where cloud moves through the branches and the ground under you is soft with needles. The light comes through grey rather than gold. A trail takes you down through the juniper to the Lamadaya falls, water coming off the escarpment face in one of the driest corners of the Horn. Herders bring their camels onto the plateau for the cooler grazing, along the tracks that run out to the frankincense slopes. Meeting a herd on a mountain road, high above the desert most people picture, rearranges the country for you. Down on the ledges the Boswellia trees root straight into bare limestone, and a harvester opens the bark with a blade called a mangaf. The cut beads white within minutes, and what he is taking is maydi, the grade Arabian buyers pay most for, and most of it is chewed rather than burned: sticky at first, then faintly of lemon on your tongue. Frankincense is not sap, though; it is scar tissue. The tree seals each injury with resin, the slit is reopened every few weeks through the season, and over-tapped trees set fewer viable seeds and die. That is why the harvesters here have started arguing about limits.