GEOGRAPHICAL AFFINITIES OF THE FLORA. 313 



Triglochin striata R. & P. 1 Yucca aloifolia L. 



*Quercus virginiana L. ' *Physalis viscosa L. 

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



* Uniola panieulata L. *Borrichia frutesceus L. 



*Fimbristylis spadicea Vahl. \Ipomoea sagittata Cav. 



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

 riparian area: Zanthoxylum clava-hercvlis and, possibly, Ilex vt mi- 

 tor ia extend northward to Virginia, while the rest attain their northern 

 limit in North Carolina. 



MuMenbergiaJUipes M. A. Curtis. Ilex vomitoria Ait. 



Yucca gloriosa L. Opuntia pes-corvl Le Uonte. 



Croton maritimus Walt. Vincetoxicumpalustre ( Pursh ) A. Gray. 



Zanthoxylum 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 carolinianum (Muhl.) Brit- 

 Scotia), ton (Labrador). 



Distichlis spicata (L. ) Greene ' 2 (Maine) . Iva frutescens L. (Massachusetts) . 



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

 sey). wick). 



Sesuvium maritimum (Walt.) B. S. P. Aster tenuifclius L. (Massachusetts). 



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



Euphorbia polygonifolia L. (Rhode shire). 



Island). Baccharis halimifolia L. (Massachu- 



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



Ammania koehnei Britton (New Jersey) . 



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

 in the Old World. 



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



Atriplex hastata L. Tissa marina (L.) Britton. 



Salicornia herbacea L. 



Of the nonmaritime species of the island, fifteen are introduced 

 and are chiefly 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, Parista- 

 ria debilisYornt., and Tillandsia usneoidesL., which, while hardly mari- 

 time, are found usually near the seacoast in the Austroriparian 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 ehar- 



1 Normally a strand plant in Virginia and North Carolina. 

 ! The typical form. 



