186 Rhodora [OCTOBER 
Festuca elatior Lychnis alba 
Holcus lanatus Chrysanthemum Leucanthemum 
Dactylis glomerata Aster undulatus 
Danthonia spicata Trifolium arvense 
Poa pratensis Trifolium pratense 
Phleum pratense Trifolium agrarium 
Rumex Acetosella Trifolium repens 
Achillea Millefolium Sonchus arvensis 
Daucus Carota Asparagus officinalis 
Solidago sempervirens Rudbeckia hirta 
Solidago rugosa Cirsium arvense 
Verbascum Thapsus Cirsium lanceolatum 
Potentilla argentea Dennstaedtia punctilobula 
Oenothera biennis Linaria canadensis 
Oxalis stricta 
One interesting retrogression in the development of the vegetation 
is due to the nesting habits of the terns. These occupy the bare ground 
so thickly that large areas are denuded of vegetation (plate 147, 
upper view). When these nesting areas are abandoned the first 
results are similar to those of the abandonment of cultivated land, 
running at once to weed forms such as: 
Solanum nigrum Anagallis arvensis 
Lepidium virginicum Erigeron canadensis 
Chenopodium album Sonchus arvensis 
Amaranthus retroflexus Capsella Bursa-pastoris 
Powps. The ponds are of two types, first, low ponds quite near 
the shore, tending to be brackish, second, higher ponds formed in kettle- 
holes. The low ponds show nearly the same development. A center 
of open water containing a scum of floating algae is surrounded by a 
zone of sedge, a zone of Spartina patens, and an irregular zone of 
Tris versicolor marking the line of tension between the pond vegetation 
and the grassland. The filled marsh on the east of the island near the 
neck shows the further development of the marsh stage. Here a larger 
number of plants are found, of which the commonest are: 
Rumex crispus Lycopus uniflorus 
Convolvulus sepium Polygonum Convolvulus 
Scutellaria epilobiifolia 
The kettle-hole type of pond is entirely freshwater in character. 
Typha Pond, on the east side of the island between the residence 
and the neck, is in a deep depression, and has a Typha zone sur- 
rounded by a band of Juncus, outside which comes the Scirpus zone. 
The marsh stage here is well developed, containing: 
