We had scarcely started, when I observed an entirely new species of plant, which is rather rare in Central Negroland, and which I afterwards met in considerable quantities along the north shore of the so-called Niger, between Timbúktu and Tosáye. It is here, in Háusa, called “kumkúmmia,” a euphorbia growing from one and a half to two feet in height, and is very poisonous; indeed hereabouts, as in other districts of Central Africa, it furnishes the chief material with which arrows are poisoned. The principal vegetation consisted of “árza” (a species of laurel) and dílu; and further on parasitical plants were seen, but not in a very vigorous state. Altogether the country announced its fertility by its appearance; and a little before noon, when low ranges of hills encompassed the view on both sides, and gave it a more pleasant character, we passed, close on our left, another pastoral settlement of half mat and half leather tents[203], enlivened by numerous cattle and flocks, and leaning against a beautiful cluster of most luxuriant trees. But more cheerful still was the aspect of a little lake or tank of considerable extent, and bordered all around with the thickest grove of luxuriant acacias of the kind called “baggarúwa,” which formed overhead a dense and most beautiful canopy. This little lake is called “Gúmrek,” and was full of cattle, which came hither to cool themselves in the shade during the hot hours of the day. In this pleasant scenery we marched along, while a good number of horsemen collected around us, and gave us a little trouble; but I liked them far better, with their rough and warlike appearance, than their more civilized and degraded brethren of the day before. At about half-past two we encamped on the border of a dry watercourse with a white sandy bed, such as we had not seen for a long time. But here we made the acquaintance of a new plant and a new nuisance; this is the “aidó,” a grass with a prickly involucrum of black colour, and of larger size and stronger prickles than the karéngia (or _Pennisetum distichum_), and more dangerous for naked feet than for the clothes. A new string of camels joined us here, led on by Mohammed Ánnur. [Sidenote: Sunday, January 6th.] We were greatly surprised at the appearance of the weather this morning; the sky was covered with thick clouds, and even a light rain fell while the caravan was loading. We felt some fear on account of the salt; but the rain soon ceased. In the course of my travels, principally during my stay in Timbúktu, I had more opportunities of observing these little incidental rain-falls of the cold season, or “the black nights,” during January and February; and further on, as occasion offers, I shall state the result of my observations.