=YAMS= (_Dioscorea sativa_, etc.).—These climbers are commonly grown in the moist valley of the Niger and in the Yoruba country of Ilorin, but are rare and only an irrigated crop in the more northern countries. Where they are seen, they are planted from root eyes upon high mounds with ditches dammed to retain the water between them, and, until the plant has grown up as a trailer upon the ground, some feet in length, no supports are put in. At this time, however, the straw covers, which it is customary to place on the apex of the yam mounds, are removed and an elaborate system of stakes, to the top of each of which strings are tied and conducted to the ground near the growing plant, are put in, and the plants to the number of four or more are trained to grow towards the top of each stake. The large white yam is chiefly grown, and is called in Haussa “Doya.” Yams attain large dimensions in the damp localities, but are small in the drier places. _Colocasia antiquorum_, called by the Haussas “Kamu,” is usually referred to as the koko yam and is rarely grown. A few may be seen in the wet localities and near Zaria, where they are planted in swamps upon high mounds or ridges. =SWEET POTATOES.=—This crop is grown everywhere, and is nearly always unmanured. It is said that it forms the occupant of the land upon which Guinea corn and millet are repeatedly grown in some parts of the Kano district in the second and eighth year—_i.e._ twice in a period of eight years. In the year of plantation, the ridges are said to be heightened. Near Bida very high beds are made for it, resembling flat-topped mounds, with an area of sixteen or more square feet. The Haussas apply the name “Dankali” to the root, which is usually of the small white variety. =Artichokes and small Root Crops.=—The Jerusalem artichoke (_Helianthus tuberosus_) called “Gwaza,” as well as “Rizga” (_Plectranthus sp._) and “Tumuku” (probably _Plectranthus sp._) are cultivated by the people living to the south of Zaria Town. “Gwaza” seems to be less planted than “Rizga,” the latter being carefully grown upon selected ground which has been previously hoed and levelled, the surface being covered over with branches of _Bauhinia reticulata_ and other forest plants until the stems of the crop have reached a height of one foot or more. Single stems spring from the root eyes which are planted. “Tumuku” resembles “Gwaza” in appearance, but comes up in clusters of stems and is planted upon mounds. All the above roots are used in the manner in which the potato is employed in Europe; cassava alone being pounded to make a kind of dough ball, in addition to being eaten in chopped up and boiled form. =Onions.=—Two kinds of onions are cultivated throughout the country: _Allium cepa_, the large onion which is seen to perfection in the Kano markets, and _Allium ascalonicum_ which is usually termed the shallot, and is cultivated to a larger extent in the localities where manure is scarce.