300 



Saccharum Ravennse, S. Teneriffae, Imperata arundinacea, Lagurus ovatus, 

 Lygeuin spartum, and the species of Stipa, by their soft, downy, elegant 

 flowers ; and the species of Andropogon, J^lgilops, &c. by separate sexes, 

 exhibit tropical qualities. The Grasses are also less gregarious, and meadows 

 seldomer occur, in the south than in the north of Europe, 



" As to -what relates to the distribution of individuals, the generality of 

 species are social plants. 



" Lastly, — Do we wish to know how this family is distributed, in respect 

 of the number of species, and where they reach their maxima and minima? 

 The following materials may supply, not indeed either a complete or faithful 

 representation, because the Grasses are not treated of by botanists or travellers 

 in general with the same care as the other families ; but they will at least 

 give some hints towards effecting that object. In Persoon's Syjwjisis, the 

 Grasses of the torrid zone form 1 -2.5th, and those of the temperate zone 

 l-22d of the whole vegetation; but when it is considered that the Grasses 

 of the former have been less investigated than the European, the quotient 

 would be nearly alike in both zones. In the systems of Romer and Schultes, 

 tropical are to the European Grasses as 2 to 3 ; but this, from a probable 

 conjecture, is also the proportion of all tropical and extra-tropical plants. 

 In Persoon's Synopsis it is as 1 to 2 ; and since the publication of that 

 work, the knowledge of tropical has been enlarged in a greater pro- 

 portion than that of extra-tropical plants. Although, however, the quo- 

 tients in the torrid and temperate zones may be nearly equal upon the 

 whole, when taken in subdivisions there will be an inequality. In the warm 

 regions of South America, the Grasses, under 200 toises elevation, form 

 from 1-1 5th to 1 -16th of the whole; in the West Indies l-17th; on the 

 river Essequibo, in Guyana, l-12th to l-15th; on the river Congo l-12th to 

 l-13th; in Guyana 1-lOth; (in the three last the local circumstances are 

 peculiarly favourable for the Grasses) ; in the East Indies, according to 

 Brown, l-12th; in Arabia l-15th; and in tropical New Holland 1-lOth to 

 1-1 1th. Now, attending to the circumstance, that tropical are scarcely 

 so well known as other phsaenerogamic plants, it is not improbable that 

 the true quotient for the torrid zone is 1-1 0th to 1-1 2th. In the warmer 

 parts of the temperate zone the Grasses appear to form a smaller proportion 

 of the vegetation ; for, in the extra-tropical parts of New Holland, they form 

 from l-24th to l-25th, at the Cape l-35th, in Greece l-15th to l-16th, in 

 the Canary Islands l-12th to l-13th, in the Crimea and Caucasus l-14th to 

 l-15th, in Naples 1-llth to l-12th, in France 1-1 3th, and in Egypt 

 (where, however, the circumstances are peculiarly favourable) I-8th. Far- 

 ther north the relative numbers seem to rise somewhat higher ; in Ger- 

 many l-13th, in Great Britain 1-llth to l-12th, in DenmWk 1-lOth to 

 l-Uth, in Scandinavia 1-lOth to 1-llth, in Kamchatka l-7th to l-8th, 

 Lapland I-lOth, Iceland l-8th to l-9th, Greenland l-Bth to l-9th, and in 

 North America, according to Pursh, ]-14th to l-15th. We may assurae, 

 perhaps, as a medium for the warmer parts of the temperate zone, 1-1 2th 

 to l-14th; for the colder, together with the polar regions, 1-^th to 1-lOlh. 

 That almost in every Flora the quotient is considerably higher than in the 

 works of Persoon, and of Riimer and Schultes, aftbrds another proof, that, 

 in the rule, the distribution of the Grasses is more extensive that that of the 

 other phainerogamic; plants. 



" In southern Europe the number of the Grasses seems to diminish 

 according to the elevation, for in the Alpine Flora they are only 1- 

 18th. Their distribution according to elevation does not, therefore, accord 

 with that of the latitude ; in South America the agreement is greater, for 

 the relative numbers are, to 200 toises, 1-1 5th to 1-1 6th; 200 to 1100 



