Nov., 1910.] A Floristic Survey of Orchard Island. 



205 



Secondary species. 



Spirodela polyrhyza 

 Lemna minor. 



Cladophora sp. 

 Ceratophyllum demersum. 



The secondary species, which are nonnally floating plants, are 

 stranded on the mud and form but a thin covering. The society 

 covers a narrow lens shaped area not more than 3 feet in its 

 broadest portion. At the normal water level the surface is sub- 

 merged, but now it is wholly exposed. The Polygonum is tall 

 and vigorous with branches from 3-4 feet tall; the Nelumbo has 

 large erect leaves and the plants are fruiting freely; the Typha is 

 stunted in growth and sterile, the largest leaves arc not more 

 than 4 feet tall. 



4. Typha-Polygonum-Bidens society, 

 Facies. 



Typha latifolia. 

 Polj'gonum emersum 



Secondary species. 



Cyperus strigosus. 

 Eleocharis acicularis. 

 Riccia fluitans. 

 Riccia sp. 



Spirodela polyrhyza. 

 Brachvthecium rivulare. 



Bidens cernua. 



Cicuta bulbifera. 



Bidens frondosa. 



Roripa palustre seedlings. 



Hibiscus moscheutos seedlings. 



Polygonum emersum seedlings. 



Society 4 occupies a narrow zone less than 3 feet in width. 

 The Typha is larger and more vigorous than in 3, but not fruiting; 

 Polygonum emersum is still conspicuous but not nearly so much 

 as in the preceding zone, while the Nelumbo lutea has entirely 

 disappeared and Bidens cernua, represented by a few large vigorous 

 plants, has come in. There are but a few of the taller herbs of the 

 secondary species; but an abundant ground cover of the Cyperus, 

 Riccia and Eleocharis. 



This zone merges into: 



5. Hibiscus-Typha society 

 Facies. 



Hibiscus moscheutos 



Secondary species. 



Taller herbs. 



Polygonum acre. 

 Triadenum virginicum. 

 Scutellaria lateriflora. 

 Cicuta bulbifera. 

 Solanum dulcamara. 

 Echinochloa walteri. 

 Homalocenchrus oryzoides. 

 Aster paniculatus. 



Typha latifolia 



Erechtites hieracifolia. 

 Impatiens fulya. 

 Galium claytoni. 

 Epilobium stricta. 

 Boehmeria cylindrica. 

 Agrimonia sp. 

 Acnida tamariscina. 



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