GEOGRAPHICAL AFFINITIES OF THE FLORA. 313 



Triglochin striata R. & P. \ Yucca aloifolia L. 



*Qaercus vir-ginianaLi.^ * Physalis viacosa ^L. 

 \Chloris petraea Sw. Monniera monniera H, B. K. 



* Uniola xKinicuUda L. *Borrichia frutescena L. 



^Fimbristylis spadicea Vahl. \Ipomoea sagittata Cav. 



2. Species mostly or entirely confined to the seacoast of the Austro- 

 riparian area: Zdidhoxyluni dava-lievculis and, X)ossibly, Ilex roini- 

 toria extend northward to Virginia, while the rest attain their northern 

 limit in North Carolina. 



Miihlenbergia filipes M. A. Curtis. Ilex vomitoria Ait. 



Yucca gloriosa L. Opuntia pes-corvi Le Conte. 



Croton maritimus Walt. Vincetoxicum palustre (Pursh) A. Gray. 



Zanthoocylum clava-herculis L. 



3. Species confined to the Atlantic seacoast of North America and 

 ranging north of the Austroriparian area. The northern limit of 

 each is cited as given in Britton & Brown's Illustrated Flora. 



Panicum amarum minus Vasey & Oenothera humifusa Nutt. (New Jer- 

 Scribn. (Connecticut). sey). 



Spartina patens (Ait.) Muhl. (Nova Limonium earolinianum (Muhl.) Brit- 

 Scotia), ton (Labrador). 



Distichlis spicata (L. ) Greene - (Maine) . Iva frutescens L. (Massachusetts) . 



Juncus roemerianus Scheele (New Jer- Solidago sempervirens L. (New Bruns- 

 sey). wick). 



Sesuvium maritimum (Walt.) B. S. P. Aster tenuifolius h. (Massachusetts). 



(New York). Aster siibidat us Michx. (New Hamp- 



Euphorbia polygonifolia L. (Rhode shire). 



Island). Baccharis halimifolia L. (Massachu- 



Kosteletzkya virginica L. (New York). setts). 



Ammania fcoe/mei Britton (New Jersey). 



4. Species occurring also on the seacoast of the northern hemisphere 

 in the Old World. 



Spartina stricta (Ait. ) Roth. Salsola kali L. 



Atriplex hastata Ij. Tissa marina {Ij.) Britton. 



Salicornia herbacea L. 



Of the nonmaritime species of the island, fifteen are introduced 

 and are chiefiy weeds of American origin. The remainder (about 

 two-thirds of the total flora) includes several mainly tropical species, 

 such as Lippia nodiflora Michx., Centella asiatica (L.) Urban, Parietn- 

 ria deb His For St., and Tillandsla tts?ieoidesL., which, while hardly mari- 

 time, are found usually near the seacoast in the Austrorix)arian area. 

 Finally, after excluding all the preceding categories except the second 

 of strand plants, we have a list of species among which the Austro- 

 riparian element is sufficiently predominant to leave no question as 

 to the general affinity of the flora. 



As previously remarked, however, many of the plants most cliar- 



' Normally a strand plant in Virgfinia and North Carolina. 

 -The typical form. 



