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15a. Upper stem-leaves distinctly narrowed at the base; introduced 

 species of waste places (summer) Spurge, Euphorbia peplus. 



15b. Upper stem-leaves rounded at the sessile base; native species of 

 woodlands (spring and early summer) 



Spurgre, Euphorbia commutata, 



CALLITRICHACEAE, the Water Starwort Family 



Small herbs growing in water or in mud, with opposite entire 

 leaves and small inconspicuous axillary flowers, with neither calyx 

 nor corolla. (Flowers in summer). 



la. Completely submerged; leaves all linear 



Water Starwort, Callitriche aiituinnalis. 

 Ib. Submerged leaves linear, emersed and floating leaves obovate 



Water Starwort, Callitriche palustris. 



EMPETRACEAE, the Crowberry Family 



Low evergreen shrubs, with the linear leaves completely rolled 

 into a tube, and inconspicuous flowers without petals, in the axils 

 of the leaves. 



One species in Michigan, 1 3 dm. high; leaves less than 1 cm. 

 long; flowers in summer Crowberry, Empetrnm nigrnm. 



LIMXANTHACEAE, the False Mermaid Family 



Low herbs with alternate compound leaves and minute axillary 

 flowers; sepals 3, petals 3, stamens 6. 



One species in Michigan, v/ith stems 1 3 dm. long, and flowers in 

 late spring False Mermaid, Floerkea proserpinacoides. 



ANACARDIACEAE, the Cashew Family 



Shrubs or small trees, with milky or resinous juice, alternate com- 

 pound leaves sometimes poisonous to the touch, and small clustered 

 greenish or yellowish flowers. 



la. Leaflets 7 to many (15 m. high) (Sumach) 2. 

 Ib. Leaflets 3 5. 



2a. Axis of the leaves wing-margined between the leaflets 



Sumach, Rims copallina. 



2b. Axis of the leaves not margined 3. 



3a. Leaflets entire Poison Sumach, Rhus yernix. 



3b. Leaflets serrate 4. 



4a. Bark of the older stems glabrous Sumach, Rhus glabra, 



4b. Bark of the older stems densely velvety-hairy 



Sumach,, Rhus typhina. 



