OCR Text |
Show 292 PHYSIOGNOMY OF PLANTS. globe? Murray's edition of the Linnean system contains, including cryptogamia, only 10,042 species. Willdenow, in his edition of the Species Plantarum between the years 1797 and 1807, had already described 17,457 phrenogamous species (from Monandria to Polygamia direcia). If we add 3000 cryptogamous species, we obtain the number which Willdenow mentions, viz. 20,000 species. More recent researches have shown how much this estimation of the number of species described and contained in herbariums falls short of the truth. Robert Brown counted above 37,000 phrenogamous plants. (General Remarks on the Botany of Terra Australis, p. 4.) I afterwards attempted to give the geographical distribution (in different parts of the earth already explored) of 44,000 phrenogamous and cryptogamous plants. (Humboldt, de distributione geographica Plantarum, p. 23.) Decandolle found, in comparing Persoon's Enchiridium with his Universal System in 12 several families, that the writings of botanists and European herbariums taken together might be assumed to contain upwards of 56,000 species of plants. (Essai elementaire de Geographic botanique, p. 62.) If we consider how many species have since that period been described by travellers-(my expedition alone furnished 3600 of the 5800 collected species of the equinoctial zone )-and if we remember that in all the botanical gardens taken together there are certainly above 25,000 phrenogamous plants cultivated, we shall easily perceive how much Decandolle's number falls short of the truth. Completely unacquainted as we still are with the larger portions of the interior of South America-(Mato-Grosso, Paraguay, the eastern declivity of the Andes, Santa Cruz· de la Sierra, and all the countries between the Orinoco, the Rio Negro, the Amazons, and Puruz )-of Africa, Madagascar, Borneo, and Central and Eastern Asia-the thought rises involuntarily in the mind that we may not yet know the third, or probably even the fifth part of the plants existing on the earth! Dn3ge has collected 7092 species of phrenogamous plants in South Africa alone. (See Meyer's pflanzen geographische Documente, s. 5 and 12.) He believes that the Flora of that district consists of more than 11,000 phrenogamous species, while on a surface of equal area (12,000 German, or 192,000 English square geographical miles) von Koch has described in Germany or Switzerland 3300, and De- |