China has 66 species of Quercus, 35 of Vitis, 2 of Aesculus, 42 of Acer, 33 Magnoliaceae (including two species of Liriodendron), 12 Anonaceae, 71 Ternstroemiaceae (including the tea-plant), and 4 of Clethra, which has a solitary western representative in Madeira.
And it is interesting to note that while the tropical forms of Quercus failed to reach Australia from Malaya, the temperate Fagus crept in by a back door.
Of Cupuliferae, Quercus in three species only reaches Colombia, but Fagus, with only a single one in North America, is represented by several from Chile southwards and thence extends to New Zealand and Tasmania.
The northern Quercus, arrested at the tropic in the new world, expanded in that of the old into new and striking races.
Quercus Ilex, the evergreen oak of southern Europe, is found in forests as far east as the Sutlej, accompanied with other European forms. In the higher parts of Afghanistan and Persia Boraginaceae and thistles abound; gigantic Umbelliferae, such as Ferula, Galbanum, Dorema, Bubon, Peucedanum, Prangos, and others, also characterize the same districts, and some of them extend into Tibet.