394 BOTANICAL SURVEY OF DISMAL SWAMP REGION. 



arenaria), and in the indehiscent siliques of Oakile and the fruits 

 with corky ridges of Diodia virginiana. 



(b) Development of special structures which serve as sails: Repre- 

 sented by the wings in Salsola kali and Tecoma radicans, and hairs 

 (pappus) in Baccharis halimifolia and Eupatorium capittifolium. 



(c) Tumble- weed structure: The entire panicle breaks off near the 

 base of the culms in Eragrostis pectinacea and E. refracta, and rolls 

 over the ground, its progress being facilitated by the horizontally 

 spreading branches, which act as sails, thus behaving like the pro- 

 longation of the rhachides in Spinifex. 1 The breaking off of the 

 panicle is expedited by the slenderness of the lowest internodes of 

 the culm. 



(2) Adaptations to transportations by animals. 



(a) Edible character of fruit: Species with fleshy fruits are rather 

 •numerous on the dunes, all hough Pin/sal is riscosa is the only strictly 

 maritime species thus characterized. Others are Diospyros virgin- 

 iana, Prunus serotina, P. angustifolia, Rubus cuneifolias, K. vilhsas 

 (canadensis), Lonicera sempervirens, Vitis rotundifolia, and V. aesti- 

 valis. 



(b) Apparatus for attachment to the hair of animals, as in the 

 burs of Xanthium sp. and of Cenchrus tribuloides macrocephalus. 



GENERAL ASPECTS OF THE STRAND VEGETATION. 



The general facies of the strand vegetation is somber ami monoto- 

 nous. Bright lines, whether of the vegetative or the Moral organs 

 of plants, are comparatively infrequent and contribute but slightly to 

 the general effect. This prevailing lack of vivid color is due partly to 

 the sparseness of the plant covering, which leaves the exposed soil as 

 one of the chief color elements in the landscape, and partly to the 

 various protective arrangments already detailed, which more or less 

 conceal the green coloring matter. Iva imbricate is almost the only 

 bright-green plant of the open dunes. On the other hand, Myrica 

 (resinous) has a brown-green color, Oenothera (villous) is almost 

 white, lludsonia (tomentous) is gray, Amniophila (thick cuticle) is sil- 

 very green, Panic um antarum (glaucous) is blue green, and Oakile 

 (succulent) is yellowish. Myrica gives the prevailing color to the 

 middle dune area. Gaily tinted flowers are those of Lonicera sem- 

 pervirens and Tecoma radicans (red), Linaria canadensis (bhie), and 

 Oenothera humifusa, Hudsonia tomentosa, and Gelsemium; the last. 

 three, being yellow, are less conspicuous amid the sands. Owing to 

 the paucity of individuals, however, even the brilliantly colored flow- 

 ers add little brightness to the aspect of this formation. 



Poverty of species, as well as of individuals, characterizes the strand 

 vegetation of this as of other regions. Only about 50 species, belong- 



1 See Goebel, Pflanzenbiolog. Sehilderungen, Theil 1. pp. 185 to KJ8 (1889) : Schim- 

 per, Indo-malayische Strand- flora, p. 81. 



