No. 14.] FLOWERING PLANTS AND FERNS. 269 



Swamps and wet ground or sometimes in drier places. 

 Occasional in most districts, becoming frequent near the coast. 

 June — July. 



All parts of the plant are poisonous to the touch, etc., as 

 in the following species, only more actively so. 



Rhus Toxicodendron L. (poison tree). 



Poison Ivy, Oak or Vine. Mercury. Marcury. 



Frequent or common. Fence-rows, fields, woods and 

 meadows, in either moist or dry ground, often climbing trees 

 and posts. May — June. 



The var. radicans (L.) Torr. (rooting), Rhus radicans 

 L., is often more plentiful than the typical form. 



A pernicious shrub or vine that is far too plentiful. To 

 most persons all parts of the plant at all seasons are poisonous 

 to the touch; and its exhalations, even at some distance, are 

 equally poisonous to some, especially in a humid atmosphere 

 or during free perspiration. The poisonous principle is be- 

 lieved to be a peculiar oil which is present in all parts of the 

 plant and which in the minutest quantity is intensely irritant. 

 Cattle and horses are not afifected by it. The leaves are valued 

 medicinally and were formerly officinal. 



Rhus canadensis Marsh. 

 Rhus aromatica Ait. 

 Sweet-scented Sumach. 



Rare. Guilford, on a small outcrop of rock in a salt marsh 

 (G. H. Bartlett). May. 



The bark of the root is an active medicinal agent. 



AQUIFOLIACEAE. HOLLY FAMILY. 

 ILEX L. Holly. 



Ilex opaca Ait. (opaque). 

 American Holly. 



Rare. Roadsides and thickets: Waterford (Miss A. H. 

 Morgan), Milford (J. D. Dana), Wolcott (H. J. Bassett). 

 May — June; fruit Oct., lasting into the winter. Escaped 

 from cultivation or possibly native. 



Plentiful in parts of the South, where it is extensively 



