234 



NA TURE 



{Jan. 8, 1885 



having been crossed and recrossed with more elegant but tender 

 Indian species. 



As to flowering herbs, somewhat of the delight with which 

 an American first gathers wild Primroses and Cowslips and Fox- 

 gloves and Daisies in Europe, may be enjoyed by the European 

 botanist when he comes upon our Trilliums and Sanguinaria, 

 Cypripedinms and Dodecatheon, our species of Phlox, Coreop- 

 sis, &c, so familiar in his gardens ; or when, crossing the con- 

 tinent, he comes upon large tracts of ground yellow with 

 Eschscholtzia or blue with Nemophilas. But with a senti- 

 mental difference : in that Primroses, Daisies, and Heaths, like 

 nightingales and larks, are inwrought into our common litera- 

 ture and poetry, whereas our native flowers and birds, if 

 not altogether unsung, have attained at the most to only local 

 celebrity. 



Turning now from similarities, and from that which inter- 

 change has made familiar, to that which is different or peculiar, 

 I suppose that an observant botanist upon a survey of the At- 

 lantic border of North America (which naturally first and mainly 

 attracts our attention) would be impressed by the comparative 

 wealth of this flora in trees and shrubs. Not so much so in 

 the Canadian Dominion, at least in its eastern part ; but even 

 here the difference will be striking enough on comparing Canada 

 with Great Britain. 



The Conifera? native to the British Islands are one Pine, one 

 Juniper, and a Yew ; those of Canada proper are four or five 

 Pines, four Firs, a Larch, an Arbor- Vita;, three Junipers, and 

 a Yew — fourteen or fifteen to three. Of Amentaceous trees 

 and shrubs, Great Britain counts one Oak (in two marked 

 forms), a Beech, a Hazel, a Hornbeam, two Birches, an Alder, 

 a Myrica. eighteen Willows, and two Poplars — twenty-eight 

 species in nine genera, and under four natural orders. In 

 Canada there are at least eight Oaks, a Chestnut, a Beech, two 

 Hazels, two Hornbeams of distinct genera, six Birches, two 

 Alders, about fourteen Willows and five Poplars, also a Plane 

 tree, two Walnuts, and four Hickories ; say forty-eight species, 

 in thirteen genera, and belonging to seven natural orders. The 

 comparison may not be altogether fair ; for the British flora 

 is exceptionally poor, even for islands so situated. But if we 

 extend it to Scandinavia, so as to have a continental and an 

 equivalent area, the native Coniferae would be augmented only 

 by one Fir, the AmentaceEe by several more Willows, a Pop- 

 lar, and one or two more Birches ; — no additional orders nor 

 genera. 



If we take in the Atlantic United States, east of the Missis- 

 sippi, and compare this area with Europe, we should find the 

 species and the types increasing as we proceed southward, but 

 about the same numerical proportion would hold. 



But more interesting than this numerical preponderance — 

 which is practically confined to the trees and shrubs — will be 

 the extra-European types, which, intermixed with familiar Old 

 World forms, give peculiar features to the North American flora 

 — features discernible in Canada, but more and more prominent 

 as we proceed southward. Still confining our survey to the 

 Atlantic district, that is, without crossing' the Mississippi, the 

 following are among the notable points : — 



(1) Leguminous trees of peculiar types. Europe abounds in 

 Leguminous shrubs or under-shrubs, mostly of the Genisteous 

 tribe, which is wanting in all North America, but has no Legu- 

 minous tree of more pretence than the Cercis and Laburnum. 

 Our Atlantic forest is distinguished by a Cercis of its own, three 

 species of Locust, two of them fine trees, and two Honey 

 Locusts, the beautiful Cladrastis, and the stately Gymnocladus. 

 Only the Cercis has any European relationship. For relatives 

 of the others we must look to the Chino-Japanese region. 



(2) The great development of the Ericaceae (taking the order 

 in its widest sense), along with the absence of the Ericeous trine, 

 that is, of the Heaths themselves. We possess on this side of 

 the Mississippi 30 genera and not far from 90 species. All 

 Europe has only 17 genera and barely 50 species. We have 

 most of the actual European species, excepting their Rhododen- 

 drons and their Heaths, — and even the latter are represented by 

 some scattered patches of Calluna, of which it may be still 

 doubtful whether they are chance introductions or sparse and 

 scanty survivals ; and besides we have a wealth of peculiar 

 genera and species. Among them the most notable in an orna- 

 mental point of view are the Rhododendrons, Azaleas. Kalmias, 

 Andromedas, and Clethras ; in botanical interest, the endemic 

 Monotropere, of which there is only one species in Europe, but 

 seven genera in North America, all but one absolutely peculiar ; 



and, in edible as well as botanical interest, the unexampled 

 development and diversification of the genus Vaccinium (along 

 with the allied American type, Gaylussacia) will attract atten- 

 tion. It is interesting to note the rapid falling away of 

 Ericaceae westward in the valley of the Mississippi as the fored 

 thins out. 



(3) The wealth of this flora in Composite is a most obvious 

 feature, — one especially prominent at this season of the year, 

 when the open grounds are becoming golden with Solidago, and 

 the earlier of the autumnal Asters are beginning to blossom. 

 The Compositae form the largest order of Phaenogamous plants 

 in all temperate floras of the northern hemisphere, are well up 

 to the average in Europe, but are nowhere so numerous as in 

 North America, where they form an eighth part of the whole. 

 But the contrast between the Compositae of Europe and Atlantic 

 North America is striking. Europe runs to Thistles, to 

 Inuloide.-e, to Anthemidese, and to Cichoriacese. It has very 

 few Asters and only two Solidagoes, no Sunflowers, and hardly 

 anything of that tribe. Our Atlantic flora surpasses all the 

 world in Asters and Solidagoes, as also in Sunflowers and their 

 various allies, is rich in Eupatoriaceae, of which Europe has 

 extremely few, and is well supplied with Vernoniacese and 

 Helenioideae of which she has none; but is scanty in all the 

 groups that pred iminate in Europe. I may remark that if our 

 larger and most troublesome genera, such as Solidag 1 and Aster, 

 were treated in our systematic works even in the way that 

 Nyman has treated Hieracium in Europe, the species of these 

 two genera (now numbering 78 and 124 respectively) would be 

 at least doubled. 



(4) Perhaps the most interesting contrast between the flora oi 

 Europe and that of the eastern border of North America is in 

 the number of generic and even ordinal types here met with 

 which are wholly absent from Europe. Possibly we may dis- 

 tinguish these into two sets of differing history. One will repre- 

 sent a tropical element, more or less transformed, which has 

 probably acquired or been able to hold its position so far north 

 in virtue of our high summer temperature. (In this whole sur- 

 vey the peninsula of Florida is left out of view, regarding its 

 botany as essentially Bahaman and Cuban, with a certain 

 admixture of northern elements.) To the first type I refer 

 such trees and shrubs as Asimina, sole representative of the 

 Anonaceae out of the tropics, and reaching even to lat. 42'; 

 Chrysobalanus, representing a tropical sub-order ; I'inckneya, 

 representing as far north as Georgia the Cinchoneous tribe ; the 

 Baccharis of our coast, reaching even to New England ; Cyrilla 

 and Cliftonia, the former actually West Indian ; llumelia, 

 representing the tropical order Sapotacea? ; Bignonia and 

 Tecoma of the Bignoniaceae ; Forestiera in Oleacea; ; Persea of 

 the Laurinea? ; and finally the Cactacese. Among the herbaceous 

 plants of this set I will allude only to some of peculiar orders. 

 Among them I reckon Sarracenia, of which the only extra- 

 North American representative is tropical American, the Melas- 

 tomaceae, represented by Rhexia ; Passiflora (our species being 

 herbaceous), a few representatives of Loasacese and Turneracese, 

 also of Hydrophyllaceae : our two genera of Burmanniacea; ; 

 three genera of Ha?modorace:e ; Tillandsia in Bromeliacere ; two 

 genera of Pontederiacese ; two of Commelynacea? ; the outlying 

 Mayaca and Xyris, and three genera of Eriocaulonacese. I do 

 not forget that one of our species of Eriocaulon occurs on the 

 west coast of Ireland and in Skye, wonderfully out of place, 

 though on this side of the Atlantic it reaches Newfoundland. It 

 may be a survival in the Old World ; but it is more probably of 

 chance introduction. 



The other set of extra-European types, characteristic of the 

 Atlantic North American flora, is very notable. According to 

 a view which I have much and for a long while insisted on, it 

 may be said to represent a certain portion of the once rather 

 uniform flora of the Arctic and less boreal zone, from the late 

 Tertiary down to the incoming of the Glacial period, and which, 

 brought down to our lower latitudes by the gradual refrigera- 

 tion, has been preserved here in Eastern North America and in 

 the corresponding parts of Asia, but was lost to Europe. I 

 need not recapitulate the evidence upon which this now gener- 

 ally accepted doctrine was founded ; and to enumerate the 

 plants which testify in its favour would amount to an enumera- 

 tion of the greater part of the genera or subordinate groups 

 of plants which distinguish our Atlantic flora from that of 

 Europe. The evidence, in brief, is that the plants in question, 

 or their moderately differentiated representatives, still co-exist 

 in the flora of Eastern North America and that of the Chino- 



