176 SIXTEENTH REPORT. 



Wood, loose-spiked milkwort, not yet noticed in Lambton Co. but are found 

 near Port Huron, Mich., and on Harsen's Island, one of the delta islands of 

 St. Clair River. 



Euphorhiaceae. Spurge Family. 



Acalypha virginica L. Three-seeded Mercury. — Frequent in fields and 

 open places. 



Euphorbia polygonifolia L. Seaside Spurge. — Common in sand along the 

 Lake Huron shore. Not noticed elsewhere. 



Euphorbia preslii Guss. Large Spurge. — Frequent in dry open ground. 



Euphorbia hirsuta (Torr.) Wiegand. Hairy Spurge. — Frequent along rail- 

 ways and in towns and cities. 



Euphorbia maculata L. Milk Purslane. — Common in open places, on 

 roadsides, and along railways. 



Euphorbia humistrata Engelm. Hairy Spreading Spurge. — In rich ground 

 on Walpole Island. Not noticed elsewhere. In my judgment the identifica- 

 tion is doubtful. 



Euphorbia marginata Pursh. Snow-on-the-Mountain. — Cultivated as an 

 ornamental plant, but escaping and persisting a few" years. 



Euphorbia coroUata L. Flowering Spurge. — Common in poor and dry 

 ground, on sand ridges, and railway embankments. This is the species 

 known in Lambton Co., Ont., and St. Clair Co., Mich., only by the popular 

 name "Go-quick." Its root is a powerful cathartic. 



Euphorbia platyphylla L. Broad-leaved Spurge. — Occasional on roadsides 

 near Sarnia. Abundant in many places on Walpole Island. 



Euphorbia helioscopia L. Wortweed. — Occasional in waste places about 

 Forest. N. Tripp. 



Euphorbia cyparissias L. Cypress Spurge. — Frequent in dry and poor 

 ground. An escape from cultivation. 



Euphorbia lucida Waldst. and Kit. Shining Spurge. — Occasional in dry 

 and sandy groinid. Spreading in sand at Point Edward. 



Euphorbia peplus L. Pettv Spurge. — Found in waste places near Forest. 

 N. Tripp. 



CaUitrichaceae. Water Starwort Famih^ 



Callitriche palustris L. Vernal Water Starwort. — Common in pools, 

 borders of ponds, and slow streams. 



Anacardiaceae. Cashew Famil3^ 



Rhus typhina L. Staghorn Sumach. — Common in dry and sandy ground. 



Rhus glabra L. Smooth Sumach — Occasional in dry ground. 



Rhus vernix L. Poison Sumach. — Frequent in wet antl swampy places. 



Rhus toxicodendron L. Poison Ivy. — Very common on shaded sand ridges, 

 in open woods and thickets, and also in swamps. Occasionally clinil)ing trees 

 as a vine, which form is designated l\v some authors as Rhus toxicodendron 

 radicans (L.) Torr., climliing poison ivy. At Point Pelee, Essex Co., Ontario, 

 a point running south into Lake Erie about 9 miles; vines over three inches 

 in diameter were noticed taking complete possession of trees 40 and 50 

 feet high. 



Rhus canadensis Marsh. Fragrant Sumach, — Very common on sand 

 ridges near Lake Huron shore. 



