ECOLOGICAL FORMS. '275 



PASTURE AND RUDERAL PLANTS. 



A considerable area towards the lower end of Ocraooke, especially 

 in -and near the village, is covered with a fine turf composed almost 

 entirely of CaprioJa dactylon, closely grazed by horses, cattle, and 

 sheep. Here and there over these pastures are scattered groups of 

 various weeds, notably Cassia occidentalis, Sporobolus indicus, and 

 Solarium carolinense, as well as a species of Xanthium, Bidens bipin- 

 nata, Chenopodium anthelminticum, Ambrosia artimisiae folia, Ver- 

 bascum thapsus, etc., all of which have undoubtedly been imported 

 into the island by the agency of man. Occasionally, strays from the 

 indigenous formations are met with here. Fleshy fungi are sparingly 

 represented. 



CULTIVATED PLANTS. 



As far as was ascertained, the only plants now cultivated upon the 

 island are fig trees (Ficus carica), which are planted about dwellings 

 and freely mature their fruit in this mild climate. Small paper mul- 

 berry trees (Broussonetia papyrifera) are established in door yards. 

 According to a statement above quoted, peach trees and potatoes were 

 formerly grown. Attempts to cultivate garden vegetables are usually 

 terminated by inroads of the sea during a gale, which leave the soil 

 strongly impregnated with salt. 



ECOLOGICAL FORMS AND ADAPTATIONS TO ENVIRONMENT. 



In considering the physical environment of plants upon Ocracoke 

 Island, and the various modifications of the vegetative organs whereby 

 they are adapted to their medium, it is evident that many of the latter 

 fall readily into two categories : (1) Adaptations protecting against the 

 mechanical action of the wind 1 and the unstable nature of the soil; 

 and (2) modifications that assist the plant, to increase or conserve its 

 supply of water. Sand-strand and salt-marsh species alike require 

 both sorts of modifications, although the latter formation is less 

 exposed to wind and the shifting of its substratum. However, not 

 only the vegetation upon loose sand, but that which covers the muddy 

 bottom of the salt marshes, must accommodate itself to a more or less 

 incoherent and mobile soil. To the first category are to be referred 

 most of the noteworthy life forms of the island, i. e., those in which 

 the epharmonic peculiarities of structure (such as are due to the 

 direct action of the physical environment) extend to the entire organ- 

 ism. To the second belong chiefly modifications of a particular organ, 

 the leaf. 



'The exposed position of the island, and its consequent relative poverty in large 

 woody growth, renders herbaceous vegetation here more than usually subject to 

 the action of the wind. 



