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LORA1NTHACEAE, the Mistletoe Family 



Parasitic plants, attached to the branches of trees. 



One species in Michigan, a- dwarf brown plant 5 20 mm. long, 

 with minute scale-like leaves, growing on the branches of Black 

 Spruce Dwarf Mistletoe, Arceuthobium pusillum. 



ARISTOLOCHIACEAE, the Birthwort Family 



Flowers greenish-brown or reddish-brown, at or near the ground, 

 with inferior 6-celled ovary. 



la. Leaves alternate, on the stem; flowers on a basal scaly branch 

 (1 4 dm. high; summer) 



Virginia Snakeroot, Aristolochia serpentaria. 



Ib. Leaves a single basal pair, bearing 1 short-stalked flower between 

 them (spring) (Wild Ginger) 2. 



2a. Lobes of the perianth ending in a tubular portion 5 8 mm. 



long Wild Ginger, Asarum canadense. 



2b. Lobes of the perianth ending in a tubular portion over 1 



cm. long Wild Ginger, Asarum canadense var. acuminatum. 

 2c. Lobes of the perianth triangular, not tubular at the end 



Wild Ginger, Asarum canadense yar. reflexum. 



POLYGONACEAE, the Buckwheat Family 



Herbs with alternate entire leaves, stipules surrounding the stem 

 above the base of each leaf, and small green, white or pink flowers 

 without petals. 



la. Erect or ascending or prostrate or floating plants 2. 



Ib. Scrambling or climbing plants, clinging by sharp recurved 

 prickles on the 4-angled stems (flowers greenish or pink, sum- 

 mer) (Tear-thumb) 32. 



Ic. Twining vines (flowers white or greenish, summer) 33. 



2a. Sepals 6, the 3 inner ones enlarging in fruit and surround- 

 ing the achenes; flowers in panicles 3. 



2b. Sepals 4 or 5 (occasional flowers may be found with 6 

 sepals, but the flowers are not in panicles) (summer) 13. 



3a. Leaves arrow-shape or halberd-shape, with 2 basal lobes (Sorrel) 



4. 

 3b. Leaves without basal lobes (Dock) 5. 



4a. Leaves halberd-shape, the basal lobes directed sidewise 



Red Sorrel, Rumex acetosella. 

 4b. Leaves arrow-shape, the basal lobes directed backward 



Green Sorrel, Rumex acetosa. 



