1903] Blankinship, — Plant-formations of E. Massachusetts 135 
14. SEA-SHOAL FORMATION. Sfalohydrophytes. 
Habitat: shallow water along the.sea-shore or in salt-marsh pools. 
Marine plants mainly sea-weeds, fixed to rocks and soil, submersed. 
Ruppia maritima, L. Potamogeton crispus, L.. 
Zostera marina, L. Various marine algae, largely F uca- 
Zannichellia palustris, L. ceae. 
15. FRESH-WATER FORMATION. JZZydrophytes. 
Habitat: fresh-water ponds, streams and ditches; free-floating 
aquatics or submersed but unattached. 
Utricularia vulgaris, L. Spirodela polyrhiza, Schleich. 
U. purpurea, Walt. Riccia fluitans, L. 
U. inflata, Walt. R. natans, L. 
Lemna minor, L. Desmids, Diatoms and other algae. 
featrisuica. E 
16. PELAGIC FORMATION. Halohydrophytes. 
Habitat: deep sea. Plants free-floating in salt water. 
Various marine algae. 
17. WaASTE-LAND FORMATION. Biophytes, 
Habitat: yards, roadsides, waste places, cultivated fields, wher- 
ever the native vegetation has. been weakened or destroyed by the 
activities of man and his domestic animals. Mainly introduced 
species; 
Taraxicum officinale, Weber. Rumex crispus, L 
Capsella Bursa-pastorts, Moench. Ranunculus bulbosus, L. 
Poa annua, L. IS doris] 
Plantago major, L. Chrysanthemum Leucanthemum, L. 
P. lanceolata, L. Cerastium vulgatum, L. 
Chenopodium album, L. Amaranthus retroflexus, L. 
Arctium Lappa, L. Medicago Lupulina, L. : 
Lepidium Virginicum, L. Cichorium Intybus, L. 
L. ruderale, L.  Xanthium Canadense, Mill. 
Leontodon autumnalis, L. Hypericum perforatum, L. 
Stellaria media, Cyrill. l Polygonum aviculare, L. 
