90 THE RELATION OF PLANTS TO TIDE-LEVELS 
The only other seed plants found in this upper littoral belt are the occasional 
inwanderers from the belt above. These are plants that are really characteristic 
of the higher belt and only push down below the boundary where the soil 
conditions are unusual, e. g., where it is either gravelly and well-drained, or 
where it is constantly saturated with fresh water. The most important of these 
wanderers from the upper belt is Solidago sempervirens, of which mature bloom- 
ing plants have been seen between 7.5 and 8 feet, and seedlings with leaves 1 dm. 
long have been seen at 6.5, and a few even at 6 feet. But the vast majority of 
plants of this species grow above the 8-foot tide-line. Jris versicolor, which we 
have included as an inhabitant of the upper littoral belt, is also a plant more 
characteristic of higher levels, but, probably because above the 8-foot level about 
this harbor there is more competition and often dense shade, on the springy 
shores that would suit Jris, the majority of plants of this species are found at 
or just below the 8-foot tide-line. 
B. ALG! OF THE UPPER LITTORAL BELT. 
We have already seen that the firm beach and the marshy shore between the 
6.5 and 8 foot levels are inhabited in common by a considerable number of 
seed plants. In fact, all but three or four of the species that may become 
dominant between these levels are found on both types of shore. 
Essentially the same thing is true of the alge of this belt. Out of more than 
30 species recorded from this upper littoral shore and the wharves at this level 
12 may be regarded as dominants, over larger or smaller areas, between seed 
plants on the shores, or on stones and logs of the wharves. These plants are: 
Anabena torulosa, Calothriz crustacea, C. fusco violacea, Enteromorpha clath- 
rata, Lyngbya estuaru, L. semiplena, Microcoleus chthonoplastes, M. tenerri- 
mus, Monostroma latissimum, Rhizoclonium riparium, R. tortuosum, Vaucheria 
thuretu. Any one of these 12 species may grow more or less by itself, or, 
commonly, in admixture with one, two, or more other species forming tangles, 
_ felts, or incrustations. These mixtures, where seed plants are for any reason 
absent or sparse, may form coatings over the surface of mud, sand, pebbles, or 
living or dead parts of the larger plants. These tangles or felts or crusts are 
found dominating shore areas of from a few square centimeters to many deci- 
meters, or rarely of several square meters, in extent. 
Of the 21 other species of alge found in this belt, some may form small and 
infrequent tufts, globules, or coatings, but most are scattered more or less 
sparsely through the felts and incrustations made up chiefly of one or several of 
the 12 dominant species mentioned above. Most of these 21 species, like the 12 
dominant ones, have been recorded from both beach and Marsh, which indicates 
their pretty general horizontal distribution about this belt. The distribution 
of the alge is in this respect comparable with that of the seed plants mentioned 
above, and helps to give its character to this belt. These 21 less common 
species of alge recorded for the upper littoral belt are the following: 
Amphithria violacee (Kitz), Anabena variabtlis, Calothriz pulvinata, C. 
scopulorum, Lamprocystis roseopersicina, Isactis plana, Lyngbya lutea, Nostoc 
spp., Oscillatoria sp., Polycystis elabens, Rivularia plicata, Rivularia sp., 
Spirulina tenuissima, Cladophora expansa, Hnteromorpha intestinalis, Ilea 
fulvescens, Ulothria (impleza?), Ascophyllum nodosum, Fucus vesiculosus, 
Bostrychia rwularis, Hildenbrandia prototypus. 
