238 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 



COMMELINACEAE. SPIDERWORT FAMILY. 



TRADESCANTIA. Spiderwort. 



T. viRGiNiANA L. Spiderwort. — One clump in a meadow near 

 the Housatonie River, Great Barrington (Walters). 



PONTEDERIACEAE. PICKEREL-WEED FAMILY. 



HETERANTHERA. Mud Plantain. 



H. dubia (Jacq.) MacM. Mud 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 Housatonie 

 River, Sheffield. 



PONTEDERIA. Pickerel-weed. 



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

 ponds and slow streams; common. 



var. angustifolia Torr. — Occasional with the type. Great 

 Barrington; New Marlboro. 



JUJvICACEAE. RUSH FAMILY. 



JUNCUS. Rush. 



Key to J uncus. 



o. 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 J. effusus, vid. p. 240. 



c'. Inflorescence terminal. 



h. 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. 



J. tenuis and varieties. 



