290 Karl M. Wiegand and Arthur J. Eames 



74. CALLITRICHACEAE (Water Starwort Family) 

 1. Callitriche L. 



a. Fruit longer than broad, slightly notched ; each half with two sharp keels 

 separated by a wide groove. 1. C. palustris 



a. Fruit as broad as or broader than long, widely notched ; each half obtusely 2- 

 keeled, with a narrow groove between the keels. 2. C. heterophylla 



1. C. palustris L. (C. verna of Cayuga Fl.) Water Starwort. 



Ditches and pools, in limy regions ; frequent. July-Oct. 



Between Summit Marsh and Spencer Lake ; Ithaca fair grounds ; n. of Ringwood ; 

 near Dryden Lake ; near Townley Swamp ; East Lansing ; Myers Point ; outlet of 

 North Spring, Union Springs ; and elsewhere. 



Nearly throughout the U. S. and Canada, but rare or absent on the Atlantic Coastal 

 Plain ; almost cosmopolitan. 



2. C. heterophylla Pursh. Water Starwort. 



Ditches and pools, often on the mud when these are exsiccated, in acid or alkaline 

 waters ; common. June-Sept. ? 



Newf. to Man., southw. to Fla., La., Mo., and Colo., including the Coastal Plain. 



75. LIMNANTHACEAE (False Mermaid Family) 

 1. Floerkea Willi 

 1. F. proserpinacoides Willd. False Mermaid. 



I )amp alluvial woods and thickets ; scarce. May. 



Enfield Glen; Negundo Woods (D. !) ; Buttermilk Creek, above the upper reservoir 

 (£>.); s. side of Amphitheater, Six Mile Creek; Ellis Hollow, below the swamp 

 (D. !) ; woods n. e. of Freeville; s. e. of Mud Pond, McLean Bogs; near Beaver 

 Brook (£>.). 



W. Que. to Ont. and Wis., southw. to Del., Tenn., and Mo. ; rare or absent on 

 the Coastal Plain and in granitic N. E. A plant of the rich soils of the Mississippi 

 Basin. 



76. ANACARDIACEAE (Cashew Family) 



1. Rhus (Tourn.) L. 



a. Leaves pinnate. 



b. Leaflets serrate ; fruit with crimson hairs ; stone smooth ; plant not poisonous. 

 c. Twigs and petioles villous-hirsute. 1. R. typhina 



c. Twigs and petioles glabrous. 2. R. glabra 



b. Leaflets entire; fruit grayish white; stone striate; plant poisonous to the 

 touch. . 3. R. Vernix 



a. Leaves 3-foliolate. 



b. Terminal leaflet long-stalked; flowers in loose clusters, appearing later than 

 the leaves, greenish ; fruit grayish white, glabrous or nearly so ; stone striate ; 

 plant poisonous. 4. R. Toxicodendron 



b. Terminal leaflet nearly sessile ; flowers in dense clustered spikes, appearing 

 before the leaves, yellow ; fruit crimson-hirsute ; stone not striate ; plant not 

 poisonous. 5. R. canadensis 



1. R. typhina L. St\ghorn Sumach. 



Drv banks and thickets, in gravelly, more or less calcareous, soils ; common. 

 July '1-15. 



Not found in the acid soils with chestnut and ericaceous plants. 



