COMPOSITION OF THE FLORA. 



91 



haminoria to Mexico. Tlic su])famiJy Eni- 

 hliiifijioidca^ includes ouh" a single genus and 

 species C()nline<l lo western Australia. No far- 

 reaching conclusions i-egarding origin or past 

 history can he deduced from the ])res(Mit knowl- 

 edge of tJK^ geographic (list I'ihut ion of tiie 

 CapparidacciV, and the fossil record is so imper- 

 fect that v<>rv little can be said regarding t!ie 

 history. 



The oidy fossil records known to mo are 

 tiie following: F. von Miiller has dcscrihed 

 somewhat uncertainly determined fruits fi-oni 

 the Pliocene of Australia as the genera Dieune 

 and Plesiocapparis. Plesiocapparis has 2 spe- 

 cies and is considered as jirohahly a m(Mnl)er of 

 the section Busheckia of the genus Capparis. 

 Schenk has described the ]>etrilie(l wood of 

 another form from the r]ip(>r Cretaceous or 

 Tertiary of Egypt under the name faj^iiari- 

 doxylon. The gcMUis Capparis is represented 

 by a well-marked Wilcox species A'ery close to 

 the existing Antillean tree Cappar'iK domuiqcnxis 

 Sprengel. There are about a hundi-ed existing 

 species of Capparis, most of them tropical, and 

 although they are found in the Elastern Hemi- 

 sphere they chiefly occur in the American Trop- 

 ics, especially in Central and South America. 

 The oldest known fossil forms are two species 

 described by me as species of Ca]5]iarites from 

 the Upper Cretaceous of Alabama (Tuscaloosa 

 formation). In addition to the Wileo.x species 

 previously mentioneil, Engelhardt has de- 

 scribed a Tertiary species from Bolivia. Many 

 years ago Unger described a Tertiary sjiecies 

 fr()m the middle Miocene of Styria, but S(diiin- 

 per considers it to be a papilionaceous form. 

 Though the fossil record of Capparis is so 

 meager, such facts as are available seem to indi- 

 cate that it originat(Ml in tiie American l']-)])er 

 Cretaceous. Many of the modern forms are 

 shrubs or small trees of the strand flora, and 

 such is believed to have been the habitat of tlie 

 Wilcox species. 



The orchn- Resales includes about 18 families 

 and more than 14,000 existing species, the 

 largest families being the Leguminosae, Rosa- 

 cea?, Saxifragacea^, and Crassulace.T. The fam- 

 ily Platanaceas, which by tiie majority of stu- 

 dents is referred to the Rosales, 1 regard as th(> 

 sole survivor of an independent <n'<ier, the Pla- 

 tanales, closely related to tiie Urticales. Some 

 members of the alliance are close to the Ranales 

 in t lieir apocarp}-, hypogyny, and the indefinite 



repetition of certain floral members. Th(> order 

 culminates in tlie relati\('ly modern Papilio- 

 nacea'. Fi\-e families of iiosales are present in 

 \\\c Wilcox llora. Of these the tlireo legumi- 

 nous faniili(>s are by far the most abundant. 



Tlie family I lamanielidacea' consists of aliout 

 lU genera and .")() s]iecies. Twelve genera arc 

 c.onlined to the Asiatic region, 1 genus is doubt- 

 fully conlined to Australia, 3 genera are Afri- 

 can, and '■') are common to Asia and eastern 

 North Anieri(ra. The family is remarkable for 

 coiilainiiig no less t.lian !) monotypie genera. A 

 consideration of tlie existing distrif)ution is not 

 only of exceeding interest, but also gives con- 

 clusive ])r<iof of an extended geologic history, 

 whieli unfortunately has not yet been unrav- 

 eled. Since the group is scarcely if at all rep- 

 resented in tlie existing or fossil Ihiras of Aus- 

 tralia its j)resent range over Asia would seem to 

 have l)een accomplished after the land connec- 

 tion witli Australia had been interru])ted. As 

 the only known Cretaceous fossil forms come 

 from North America, the group nniy hav(> origi- 

 nated in tlie North AmiM'ican region. The fos- 

 sil s]i(>eies are n()t lunuennis enough, however, 

 for deiinite conclusions on this point. 



The genus Hamaraelis and its generalized fos- 

 sil type Ilamamelites Saporta are represented 

 by .5 species in the Dakota sandstone, one of 

 which occurs in the U]iper Cretaceous of the 

 Atlantic coast (Middendorf arkose meml)er of 

 Black Creek formation of South Carolina) and 

 another is doubtfully re])resented in the su])- 

 posed I'pper Cretaceous of Argentina (Kurtz). 

 There are 2 Paleocene species in France and 

 Belgium, and ConwiMity, has described charac- 

 teristic flowers preserved in perfection in the 

 Baltic andier (Sannoisian) as Ilamamelidan- 

 thium. 



The genus Parrotia, which includes a single 

 existing species of northern Persia and the Cau- 

 casus, contains .3 species in the Dakota sand- 

 stone, 1 s])eeies in the Wilcox and Fort Union, 

 '2 in tlie Oligocene of Europe, and 2 in the Mio- 

 cene of Spitzbergen, Spain, France, Silesia, 

 Austria, and Hungary. The distribution of 

 Parrotia in the past, so far as it is known, con- 

 firms the evidence of a North American origin 

 for the family derived fi"om Hamamelis. 



The third genus with a geologic history is 

 Liquidambar, of which more than 20 fossil 

 species have been described. The oldest known 

 forms occur in the Eocene at such widely sepa- 



