I9I4.] SOUTHEASTERN NORTH AMERICA. 247 



The order Personales or Labiatiflorae includes sixteen families dis- 

 tinguished from the Polemoniales by the zygomorphism of the flow- 

 ers. The specific differentiation is great and the lines of descent 

 are confusing. The largest families are the Labiatae with over 3,000 

 existing species, the Scrophulariaceae with^ about 2,500, the Acan- 

 thacese with about 2,000, and the Solanaceje wuth about 1,800. Two 

 of the sixteen families, the X^erbenaceae and Solanaceas, are repre- 

 sented in the Wilcox flora. 



The family A'erbenaceae includes about 73 genera and 1,300 ex- 

 isting species of widely distributed herbs, shrubs, or in tropical coun- 

 tries trees. The family is largely tropical or subtropical and is 

 notably represented in the South American region. The fossil record 

 is most incomplete. The largely old world genus Clerodcndron 

 Linne is unmistakably present in both the Eocene and Oligocene of 

 Europe, and Ettingshausen has referred, somewhat doubtfully de- 

 termined forms from the European ^Miocene to the American genus 

 Pctrcc Linne and to the cosmopolitan genus Vitex Linne. The 

 genus Citharexylon Linne has about twenty existing species rang- 

 ing from the Florida keys and lower California through the Amer- 

 ican tropics to Bolivia and Brazil. A single species found in the 

 middle and upper Wilcox is extremely close to the existing Citharex- 

 ylon villosum Jacquin, a small coastal tree of the Florida keys, Ba- 

 hamas and Antilles. With the exception of one or two doubtfully 

 determined forms in the ^Miocene of southeastern Europe it is the 

 only known fossil form. 



The genus Avicennia Linne sometimes made the type of a dis- 

 tinct family, the Avicenniaceae or Black-mangrove family, includes 

 from three to thirty existing species according to the varying inter- 

 pretation of different students. They are found on all tropical tidal 

 shores. Two species have been recognized in the Wilcox flora, one 

 based on leaves and the second on a not conclusively identified 

 capsule. 



The family Solanaceas includes about seventy genera and about 

 1600 existing species, widely distributed and largely tropical, but 

 extending into the temperate zone, notably in the western hemisphere. 

 They comprise herbs, shrubs, vines, or in tropical countries often 

 trees, with opposite, stipulate, toothed, lobed or dissected leaves. 



