EFFICIENCY (>F HKA<"H (JKASS K>K SAND BINDING. 29 



action of the rootstocks may be observed is where an area covered 

 Avith beacii «(rass ))econies rejuvenated. Here, the places most thickly 

 overthrown with the o;rass arc the last to be eroded hv the wind. The 

 grass stems and I'xposed rootstocks hano-iii(r loosely over the sides of 

 the eroded hillock protect it to a considerable extent and retard its 

 ultimate reduction. So far as observed the rootstocks seldom form a 

 thick mat-like mass sufficiently near the water's edge to be of mate- 

 rial assistance in reducing the eroding action of the Avaves, except in 

 severe storms, when the wave action extends inland for a considerable 

 distance (Fl. II, fig. 1). The chief value of the grass in this instance 

 is the accunnilation of sand induced, whi(;h, })y its presence, keeps the 

 destruction of the property adjoining the water reduced to a mininuun. 



Beach grass ordinarily requires a gradual accumulation of sand 

 over its crown to induce a normal \'igorous growth. It is for this 

 reason that it is to be noted in great clumps protruding from the crest 

 of small dunes, where it has accumulated a considerable quantit}^ of 

 sand each 3'ear, but at the same time not enough to cover it so deeply 

 that the new plants are unaldo to develop. This is due to the fact 

 that when the grass becomes partially buried the sand is no longer 

 held by the protruding grass leaves and it passes over, and the grass is 

 able to renew its growth the following vear with increased vigor, 

 since the accunudated sand is permeated with the roots of the new root- 

 stock sent out by the half- buried clump. A healthy growth of beach 

 grass can thrive where the l)urial by sand is not over a foot per year. 



The areas which usually require planting are generally those from 

 which the sand is Ijcing removed by the w'ind rather than those which 

 are receiving the accunudations so essential to the vigor of the grass. 

 For this reason the most that can be expected of the grass is that this 

 sand removal shall be checked as long as the grass is able to survive 

 under the unfavorable conditions, which allow of no accumulation of 

 sand over the plants. The decrease in vigor of the sets from the time 

 they are set out is a matter of common knoAvledge to those who have 

 noted the plantations of beach grass under these conditions for a series 

 of years. (See mortality table, p. 25.) It appears that this necessity 

 for sand accumulation lies in the fact that it induces the development 

 of new roots'tocks by the old plant and thus occupies an unused por- 

 tion of the sand which presents such a dearth of food salts that these 

 are soon depleted and the deterioration noted uuist ensue unless new 

 areas of sand are made tributar}'. Furthermore, there is no power of 

 downAvard groAvth on the part of the rootstocks, and as a set rarely 

 possesses more than tAvo nodes the root S3^stem is A^erA' limited. 

 The new rootstocks dcA'cloped in the accumulated laA^ers of sand 

 constitute the only means of bringing new supplies of sand Avithin 

 reach of the grass plants. The old rootstock becomes l)uried, but con- 

 tinues to support to some extent the new plants until sufficiently 



