98 



LOWER EOCEXK FLORAS OF SOUTHEASTERN NORTH AMERICA. 



liiirdt has doscrihod spocios of Ticorca, Pilocsir- 

 pus, aiul Ervthrochvton from the early Tertiary 

 of Chile and a species of Con<huiinea from tliat 

 of Colombia. 



Tiie remauiing genus, \vhieli is re])reseiitcd 

 l)y fossil representatives, is Ptelea Liniie, wliich 

 iucliides 7 or 8 existing species confined to the 

 I'nited States and Mexico. Greene lias re- 

 cently descrihed very many poorly established 

 new species of this genus. The fossil forms are 

 represented by botli leaves and characteristic 

 fruits. The oldest conies from the Arctic 

 Eocene. A species is foTuid in the Oligocene of 

 Italy, and 6 Miocene species occur in Colorado, 

 France, Switzerland, Carniola, and Hungary. 

 A Pliocene species is recorded from Italy. 

 Obviously the record will have to be greatly 

 increased l)efore any trustworthy conclusions 

 can be drawni respecting the place of origin and 

 geologic history of the Rutacese. 



The family Simarubaceae (often spelled Sinia- 

 roubacea'") includes about 28 genera and more 

 than 1.50 existing species of shrubs or trees that 

 have pinnate leaves and drupaceous fruits. 

 It is confined chiefly to the Tropics and the 

 warmer parts of the Northern Hemisphere. 

 Only 3 existing species reach the coast of south- 

 ern Florida. The family is represented on all 

 the continents except Europe. Two genera 

 and 4 species are confined to Asia, 3 genera and 

 4 species are confined to Australia, 4 genera and 

 6 species are confined to Africa, and 9 genera 

 and 71 species are confined to America. The 

 most widespread species is the monotypic 

 Suriana. mavitima Linne, a cosmopolitan trop- 

 ical strand plant which occurs on the dunes, 

 keys, and coastal hammocks of southern 

 Florida. 



TJH^ only genus represented in the Wilcox is 

 Simaruba Aublet, which contains a single spe- 

 cies, SiriKiruha eocenica Berry, that closely 

 resembles the existing Sirnm-uba glauca De 

 Cajidolle, foinid along tropical coasts from 

 southern Florida to Brazil. 



The only other existing genus of which fossil 

 forms are known is Ailanthus Desfontaincs, 

 which contains 7 existing species in eastern 

 Asiii and the East Indies. Ailauthophyllum 

 Dawson, which includes a single species, is 

 described from the Eocene (?) of British Co- 

 lunil)ia. The fossil species of .Ailanthus num- 

 l)er about 15. There are 2 species in tiie Eocene 

 of WvomLng and Oregon; S in the Oligocene 



of France, Alsace, Styria, and Prussia: and 5 

 in the Miocene of France, Switzerland, Badeji, 

 Italy, and Colorado. In tiie absence of col- 

 lateral evidence that the ICocene occurrences in 

 North America have any bearing on the origin 

 of the genus, it is merely an interesting specu- 

 lation that the genus originated in North 

 America and subsccpiently reached Asia by way 

 of the Eocene hind connection across Bering 

 Straits. Certahily tlie genus lingered on this 

 continent, as is indicated by its presence at 

 Florissant as late as the middle Miocene. 



The family Meliacene contains about 42 gen- 

 era and about 6S0 existing species of shrubs 

 and trees that bear pinnate leaves. Nearly all 

 of these forms range within 30° of the Equator, 

 though tlicy reach 40° north latitude in ciustern 

 Asia and 40° south latitude in New Zcdand. 

 Moreover, the chinaberry {Mflia azedaracli), 

 wliich has been cultivated from time immemo- 

 rial in aU Mediterranean comitries and tlirough- 

 out the southeastern United States since its 

 settlement and is perfectly hardy, has no tem- 

 perate outliers. Though the Meliaceje occupy 

 a greater continuous area in South America, 

 where more than 41 per cent of the existing 

 species occur, the large number of species 

 (about 285) found there represents only 19 per 

 cent of the known genera. There are some re- 

 markable similarities between the species of the 

 American Tropics and those of West Africa. 

 Thus the two small genera Swietenia and Ca- 

 rapa are represented in ])otli areas, and Carapa 

 procera is even said to l)e conunon to the two. 

 Moreover, the genus Guarea, which includes 

 about 80 species in the American Tropics, is rep- 

 resented by 3 species in West Africa. The 

 larger number of genera are fomid in the south- 

 eastern Asiatic region, and the number of gen- 

 era and their mutu:d affinities decrease from 

 Asia towaril Africa and also tlnough Polynesia. 

 Several genera (Toona, Xylocarpus, Cipadessa, 

 and M(?lia) extend from ^Vfrica tlirough Asia to 

 Malaysia. Two genera are peculiar to Austra- 

 lia (Synoum and Owenia) and 2 to Polynesia 

 (Vavsea and Meliadeljiha). There are 13 mon- 

 otypic genera, of wliich 6 are xVfrican and 7 

 Asiatic. From the distribution of the existing 

 species De CandoUe ' infers tiiat southern Asia 

 is the center of radiation of tlie family. I am 



' De Candolle, C, On the geographical distribution of the Meliaceffi; 

 Linn. Soc. London Trans., 2d sor., Botany, vol. 1, pp. 233-236, pis. 30, 

 31, 18S0. 



