There are two grasses, growing in the desert, which are of some value; both are called Esparto or Halfa. They are very dry, woody, or rather wiry grasses, especially common in Algeria, Tripoli, and also found in Spain. One of them, _Stipa tenacissima_, grows in rocky soil in Morocco, Algeria, and Tripoli. The Arabs search for it in the hills, and dig it up by the roots; they then load their camels with the grass and bring it to the ports whence it is sent to London or other places. A very good and durable paper is made from it, and ropes, mats, and even shoes are also produced from the fibre. Part of the "esparto" is, however, furnished by another grass (_Lygeum sparteum_). The natives sometimes tie a knot in a halfa leaf, which, according to them, cures a strain of the back. The Stipa is also used as fodder, but it is not nutritious and is indeed sometimes dangerous. In one year Britain imported 187,000 tons of esparto, worth nearly £800,000. The yield is said to be about ten tons per acre. Another very interesting plant at Tripoli and in the North African Desert generally, is a sort of broom, the Retama (_Retama Raetam_). It is not very unlike the common broom, but has long, leafless, whip-like branches covered by bright pink-and-white flowers. It can often be seen half submerged in waves of sand, and struggling nevertheless to hold its own. As it has no leaves its loss of water is very much kept down. This is the Juniper of the Bible, and it is still used for making coals. The length of the roots is very great in most of the broom-like, "hedgehog," and other plants. A quite small plant not more than six or eight inches high will have a root as thick as one's thumb. Even at a depth of four or five feet below the surface its root will be as thick as the little finger, so that the root-length is at least twenty times the height of the visible part above ground. These thirsty roots explore the ground in every direction, and go very deep downwards in their search for water. Another very interesting plant in the Egyptian Desert is _Citrullus Colocynth_, from which the drug colocynth is prepared. The great round yellow-green fruit and finely divided bright green leaves may be seen lying on the sand. It remains green all the summer, but appears not to have any particular protection against loss of water. It is always supplied by its roots with underground water. If a stem is cut through it withers away in a few minutes. This is found also in Asia Minor, Greece, and Spain. The pulp of the fruit contains a strong medicinal substance; it is a drastic purgative, and in overdoses is an irritant poison. This was probably the Wild Vine or gourd which the young prophet gathered, and which produced "death in the pot." He probably mistook it for a water melon. It is still plentiful near Gilgal (2 Kings xiv. 38-41).[64] [64] Ridley, _Pharmaceutical Journal_, May 19th, 1900.