Nov., 1910.] A Floristic Survey of Orchard Island. 
205 
Secondary species. 
Spirodela polyrhyza Cladophora sp. 
Lemna minor. Ceratophyllum demersum. 
The secondary species, which are normally 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 are not more 
than 4 feet tall. 
4. Typha-Polygonum-Bidens society, 
Facies. 
Typha latifolia. 
Polygonum emersum 
Secondary species. 
Cyperus strigosus. 
Eleocharis acicularis. 
Riccia fluitans. 
Riccia sp. 
Spirodela polyrhyza. 
Brachythecium rivulare. 
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. fl'here 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 fulva. 
Galium claytoni. 
Epilobium stricta. 
Boehmeria cylindrica. 
Agrimonia sp. 
Acnida tamariscina. 
Bidens cernua. 
Cicuta bulbifera. 
Bidens frondosa. 
Roripa palustre seedlings. 
Hibiscus moscheutos seedlings. 
Polygonum emersum seedlings. 
