No.l.] GRAY AND HOOKER ON THE ROCKY MOUNTAIN FLORA. 60 



nesses throughout, each region has some peculiar features — some trees by which thn 

 country may at once be distinguished. 



Beginning by a comparison of our Pacific with our Atlantic forest, I need not take 

 the time to enumerate the trees of the latter, as we all maybe supposed to know them, 

 and many of the genera will have to be mentioned in drawing the contrast to which I 

 invite your attention. In this you will be impressed most of all, I lliiiik, with the 

 fdct that the greater part of onr familiar trees are " conspicuous l)y their absence " from 

 the Paeilic forest. 



For example, it has no Magnolias, no Tulip-tree, no Papaw, no Linden or Basawood, 

 »ud is very poor in Maples; no Locust-trees — neither Flowering Locust nor Honey 

 Locust — nor any leguminous tree ; no Cherry large enough for a timber-tree, like our 

 wild Black Cherry ; no Gum-trees (Nyssa nor Liquidambar), nor Sorrel-tree, nor Kalmia ; 

 no Persimmon or Bumelia ; not a Holly ; only one Ash that may be called a timber-tree; 

 no Catalpa or Sassafras; not a single Elm nor Hackberry; not a Mulberry, nor Planer- 

 tree, nor Madura ; not a Hickory, nor a Beech, nor a true Chestnut, nor a Hornbeam ; 

 barely one Birch-tree, and that only far north, where the differences are less striking. 

 But as to coniferous trees, the only missing type is our Bald Cypreas, the so-called 

 Cypress of our southern swamps, and that deficiency is made up by other things. But 

 ae to ordinary trees, if you ask what takes the place in Oregon and California of all these 

 missing kinds, which are familiar on our side of the continent, I must answer, noth- 

 ing, or nearly nothing. There is the Madroha (Arbutus) instead of our Kalmia (both 

 really trees in some places) ; and there is the California laurel instead of our southern Red 

 Bay tree. Nor in any of the genera common to the two does the Pacific forest equal the 

 Atlantic in species. It has not half as many Maples nor Ashes nor Poplars nor Walnuts 

 nor Birches, and those it has are of smaller size and inferior quality ; it has not half as 

 many Oaks ; and these and the Ashes are of so inferior economical value that (as we are 

 told) a passable wagon-wheel cannot be made of California wood, nor a really good 

 one in Oregon. 



This poverty of the western forest in species and types may be exhibited graphic- 

 ally, in a way which cannot fail to strike the eye more impressively than when we 

 say that, whereas the Atlantic forest is composed of 66 genera and 155 species, the 

 Pacific forest has only 31 genera and 78 species. * In the appended diagrams the short 

 side of the rectangle is proportional to the number of genera, the long side to the num- 

 ber of species. 



Now the geograj)hical areas of the two forests are not very difierent. From the 

 Gulf of Mexico to the Gulf of Saint Lawrence about twenty degrees of latitude inter- 

 vene. From the southern end of California to the peninsula of Alaska there are twenty- 

 eight degrees, and the forest on the coast runs some degrees north of this ; the length 

 may therefore make up for the comparative narrowness of the Pacific forest region. 

 How can so meagre a forest make so imposing a show f Surely not by the greater 

 number and size of its individuals, so far as deciduous (or more correctly non-conifer- 

 ous) trees are concerned; for ou the whole they are inferior to their eastern brethren 

 in size if not in number of individuals. The reason is that a larger ])roportion of the 

 genera and species are coniferous trees ; and these being evergreen (except the 

 Larches), of aspiring port and eminently gregarious habit, usually dominate where 

 they occnr. While the East has almost three times as many genera and four times as 

 many species of non-coniferous trees as the West, it has slightly fewer genera and 

 almost one-half fewer sjiecies of coniferous trees than the West ; that is, the Atlantic 

 -coniferous forest is represented by 11 genera and 25 species ; the Pacific by 12 genera 



* We take in only timber trees, or such as attain in the most favorable localities to 

 a size which gives them a clear title to the arboreous rauk. The subtropical southern 

 extremity and keys of Florida are excluded. So also are one or two trees oi the Ar- 

 izouiau region, which may touch the evanescent southern borders of the Califoruiau 

 forest. In counting the coniferous genera, Piuus, Larix, Picca, Abies, and Tsuga are 

 admitted to this rauk, but Cupressus and Chama'cyparis are taken as one genus. 



