238 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 



COMMELINACEAE. SPIDERWORT FAMILY. 



TRADESCANTIA. Spidbrwort. 



T. viEGiNiANA L. Spideewoet. — One clump in a meadow near 

 the Housatonic River, Great Barrington (Walters). 



PONTEDERIACEAE. PICKEREL-WEED FAMILY. 



HETERANTHERA. Mud Plantain. 



H. dubia (Jacq.) MacM. Mtro Plantain. — Shallow ponds and 

 sluggish streams; occasional in the valley. Muddy Pond, Washing- 

 ton (altitude 1450 feet); Pontoosuc Lake, Pittsfield; outlet of Stock- 

 bridge Bowl, Stockbridge; Crane and Cranberry Ponds, West Stock- 

 bridge; Lake Buell, Monterey (Walters); lagoons of the Housatonic 

 River, Sheffield. 



PONTEDERIA. Pickerel-wbed. 



P. cordata L. Pickeeel-weed. — Shallow water, margins of 

 ponds and slow streams; common. 



var. angustif olia Torr. — Occasional with the type. Great 

 Barrington; New Marlboro. 



JUNCACEAE. RUSH FAMILY. 



JUNCUS. Rush. 



Key to J uncus. 



a. Inflorescence appearing lateral; the involucral leaf erect, similar to and 

 continuing the naked, or essentially naked scape;' rootstock creeping. 



Stamens 3. Rare /. filiformis. 



Stamens 6. Common but extremely variable, represented in Berkshire Co. 

 by four varieties, differing in the size and arrangement of flowers, and 



the thickness of the culms /. efusus, vid. p. 240. 



a'. Inflorescence terminal. 

 b. Leaves never septate, i. e., with no transverse divisions. 



c. Annual with soft base and fibrous roots, stems low and slender; 



flowers remote /. bufonius. 



c'. Perennial, flowers mostly aggregated, leaves flat (in age becoming 

 involute). 

 d. Base not bulbous. 



e. Auricles at the summit of the sheaths scarious, whitish, conspicu- 

 ously extended beyond the point of insertion. 



/. tenuis and varieties. 



