384 BOTANICAL SURVEY OF DISMAL SWAM1' REGION. 



with other factors are due some of the interesting life forms which 

 strand plants exhibit. The most notable of these are: 



1. Long, branching rootstoeks, which send up numerous leafy or 

 flowering branches. These are either slender and creep near the sur- 

 face of the sand, as in Ammophila, 1 Galium hispidvlurn (longest more 

 than 9 decimeters — .'} feet), and Scirpus a/mericanus, which last grows 

 in moist sand and has rootstoeks usually rather stouter than those of 

 the others; or the rhizomes are stout and descend obliquely or almost 

 vertically deep into the sand, as in I'niola pantritlafa (one rootstock 

 was actually traced decimeters (2 feet), and was probably a meter 

 or more in length), Panicum amarum, 2 and Iva imbricata, which has 

 rootstoeks at least 9 decimeters (3 feet) long. 



Physalis viscosa resembles Galium hispidulum in habit, but in this 

 case it is from slender branched roots, having a maximum length of 

 over 12 decimeters (4 feet), that the low, leafy, and flowering shoots 

 originate. Such habit of growth is immensely serviceable to strand 

 plants, as it goes far toward securing them from being uprooted, and 

 likewise protects them from burial by the sand. For, while by an 

 occasional movement of the sands the above-ground stems maybe 

 completely overwhelmed, the subterranean parts continue to grow 

 forward and to send up new branches, which unfold leaves and flow- 

 ers. :! The more deeply penetrating rootstoeks are also useful to the 

 plant by insuring it. a constant supply of water. 



Shrubs and small trees among the dunes often develop greatly 

 elongated roots, although these are not to be compared in length with 

 the roots, enormously extended in proportion to the si em length, that 

 have been detected in many desert plants."' This was particularly 

 observed in Pinus tarda, of which small specimens showed a stem 

 less than 1 meter (.'{ feet) high, but had roots at least 5 meters (over 

 10 feet) long. An individual of XanfJtoxyltim cla ra-hereulLs was even 

 more remarkable, having a stem less than three decimeters (1 foot) 

 and roofs 4£ meters ( 1 5 feet) long. 



2. Stems trailing over the ground, but usually not attached to it by 



1 The longest rootstock of this grass which was examined measured .'{ meters (10 

 feet), while the thread-like, much-branched roots are sometimes considerably over 

 a meter (4 feet) long. In other localities a much greater extension of the root- 

 stock lias been observed. 



' 2 ln Uniola paniculata and Panicum amarum the roots, as well as the rootstoeks, 

 are stouter than those of Ammophila. 



'"The Bpecies of the genera Agropyrum and Ammophila | after burial in the 

 sand] present a curious arrangement. At ea^h of the nodes cf their long stolons 

 creeping beneath the surface of the soil, a small branch, often forked at apex, is 

 developed, which g:o\vs vertically upward and whose length depends upon the 

 thickness of the stratum it must traverse; its growth only ceases when it reaches 

 the surface, whether that be near or distant. The leaves developed upon these 

 ascending branches are always directed toward the light, in spite of the burial of 

 the plant." Massart, Mem. Soc. Roy. Bot. de Belgique, vol. 32, pt. 1, p. 31. 189;J. 



J Compare Volkens, Flora der iigyp.-arab. Wuste, pp. 24, 25, and Coville, Contr. 

 U. S. Natl. Herb., vol. 4, p. 47. 



