COMPOSITION OF THE FLORA. 



99 



inclined to tliiiik. iiowovpr, that he is mistaken, 

 since tile oldest: known forms, exce|)t the en- 

 tirely doubtl'nl Ced i-elospermites of Sa|)ort!i 

 from tlH> N'alantjinian of P(irtnii;al. are Ameri- 

 can, and the widespread existini; American rep- 

 resentatives of tile family seem to com|)rise the 

 specilically mult i])lie(l descendants of tlie orit^i" 

 njj stock idready repres(>nted in I lie Wilcox 

 flora. 



Tiie Asiatic ijenera would thus represent im- 

 miijrants into that area or forms evolved tlierc' 

 The Polynesian and Australian forms are mucii 

 localized derivatives of the Indian stock, and 

 unless the peculiar species of New Caledonia 

 could not reach that region except hy a laud 

 connection it may he infciTed tiiat tiiis Asiatic 

 radiation was relatively recent. 



Tlie fossil species are mifortunately few. vSo 

 far as I know the only fossil species of Carapa 

 is that found in the Wilcox, where it may have 

 been a mangrove plant, as is the existing Carapa 

 ohovafa. The oriental Carapa mohiccensis and 

 the occidental Carapa proccra are also coastal 

 tj'pes. The occuiTence of Carapa in tlie early 

 Eocene at least helps to explain its present dis- 

 tribution in both the American and West .African 

 Tropics. As Carapa procera. is common to these 

 two areas, all the African species are perhaps 

 recent immigrants, but it is more proliahle that 

 there are unrecognized specific differences in 

 this form in the two areas and that the present 

 disconnected distribution is an example of sur- 

 vivoi-s from the early Tertiary radiation. An- 

 other genus whose modern distribution is like 

 that of Carapa is Moschoxylon Jussieu (made a 

 section of Trichilia Linne hy Harms in Engler 

 and Prantl), which includes about 60 species in 

 tropical America and West Africa. This genus 

 is represented by 2 fossil species described by 

 Engelhardt from the early Tertiary (Eocene or 

 OUgocene) of Chile and by a third species from 

 Colombia. The genus Cedrela, sometimes made 

 the type of an independent family, the Cedrela- 

 cese, is represented by 4 Wilcox sp(>cies. Eocene 

 prototypes of existing jVmerican species. This 

 genus, which includes 9 or 10 species, is con- 

 fined to America in the existing flora and is only 

 known outside tiiis area in '2 sjjecies from tiie 

 Miocene of Croatia, which Unger referred to 

 Cedrela, and an undescribed Cedrela recorded 

 by Ettingshausen from the Yj)resian of thci 

 south of England. Saporta has, however, re- 

 corded 6 species of Cedrelospermum from tlie 



Sannoisiaii of soullieastern l-'rance, and Deune 

 n^conls a Cedrelopliyllum from the Tertiary of 

 N(>w South Wales. The fossil rcM'ord of these 

 three genera, Carapa, Moschoxylon, and Ceth'ela, 

 brief as it is, shows clearly that the Meliacea^ 

 an^ not a modern element: in the flora of the 

 American Trojjics, hut were ah'ead\- weU differ- 

 entiated in the early Tertiary. 



The remaining fossil references to this fanhly 

 comprise Meliacciecarpura, based on capsides 

 from the A()uitanian of Prussia, which Menzel, 

 th(Mr describer, compares willi those of tlie gen- 

 (>ia Dysoxyhmi and (iuarea. 1"'. von Miiller 

 has descrihed Rliytidotheca and Pleioclinus, 2 

 supposed meliaceous genera, l)ased on fruits 

 from tlie Pliocene of Australia. 



The small family IIumiriac(>iv comprises oidy 

 •i genera and a score of species of shrubs and 

 snniU trees, all conlined to the American Tropics, 

 except a single species that is found in trof)ical 

 West^Vfrica (Aubrya), a distribution suggesting 

 a history like that just suggested for Cara|)a, 

 Moschoxylon, and (Vdrela. The only known 

 fossil species is one from the Wilco.x that is vei'y 

 close to the existing Vantanra panlculata Urban 

 of northern Soutli America. 



The family Mal])ighiacea', wliicii is confined 

 to tropical and subtro])ical countries, contains 

 aliout 55 genera and 650 existing species, 

 many of which are scandent, including some 

 of the finest lianas of the Tropics, whose stems 

 are as much as 2 decimeters in diameter. 

 Others are shrubs and trees. The leaves are 

 opposite and simple and the fruits drupaceous, 

 capsular, or nutlike, and many of them winged. 

 The only species that reaches the Ihiited 

 .Statefe is Byrsonima lucida (Swartz) De Can- 

 doUe, a small evergreen tree of the Florida 

 K(\vs. 



The family is ]:)redominantly American in 

 its distribution, more than 67 per cent of 

 both genera and species being confuied to the 

 Western Hemisphere (37 genera and 141) 

 species). None of the genera occur in more 

 than one continental area. The family is 

 di\ided into two subfamilies — the P\Tamido- 

 tor:e and the Planitora-. The Planitoiw, 

 wdiich includes 2 tribes, the (jal])liinrie;r 

 and the Malpighiea>, is entirely American. Of 

 the 3 tribes into which the P_>Tamidotorai is 

 divided the Tricomariea^ is entirely American. 

 The HiraH!ic includes 3 genera and 23 species 

 confined to Asia, 3 genera and 12 species 



