Hill: Penobscot Vegetation 371 



where considerable sand may be present. A true sand 

 beach is rare enough to be a curiosity and dune development 

 is entirely absent. 



The lozcer beach. As in the preceding type a lower 

 beach is present, which ordinarily is devoid of vegetation. 

 Occasionally, just below high tide level, rocks may occur 

 on the beach and these afford enough protection from wave 

 action so that various halophytic seed plants can gain a 

 foothold between them and give rise to a miniature salt 

 marsh. This is especially true where the beach overlies a 

 clay soil and the ground between the stones is somewhat 

 muddy. Common species in such areas, which are inundat- 

 ed at every tide, include: 



Puccinellia paupercula Suaeda maritima 



var. alaskana Limonium trichogonum 



Spartina patens Glaux maritima var. 



Car ex maritima obtusifolia 



Juncus Gerardi Plantago decipiens 



The middle beach. Vegetation is much more abundant 

 on the middle beach and the presence of large amounts of 

 driftwood aids the plants in securing a foothold in the 

 gravel and sand (Figure 21). Many of the species found 

 here are those characteristic of sand beaches in other re- 

 gions, namely : 



Ammophila arenaria Salsola Kali 



Elymus arenarius var. Atriplex pat/da var. hastata 



villosus Arenaria peploides var. 



Agropyron re pens robust a 



Rwmex pallidas Cakile edentula 



Chenopodium album Lathyrus maritimus 



The upper beach. As in the case of shingle beaches the 

 upper beach is rarely of any size, occurring usually as a 

 narrow fringe bordering on the uplands. In addition to 

 the plants cited as characteristic of the middle beach the fol- 

 lowing species are common : 



