IOWA ACADEMY OF SCIENCE 
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214. Car ex vesicaria L. Yar. monile. (Tuckherm) Fern. Necklace 
Sedge. Not uncommon in marshes and along ditches and 
streams. 
215. Carex retrorsa Schwein. Retrorse Sedge. In bogs' and marshes. 
216. Carex grisea Wahlenb. Yar. angustifolia Boott. Narrow-leaved 
Sedge. Rare in woodlands. 
ARACEAE. 
ARISAEMA Martius. 
217. Arisaema triphyllum (L.) Schott. Jack-in-the-Pulpit. Common 
in woodlands. 
218. Arisaema dracontium (L.) Schott. Green Dragon. Less com- 
mon but plenty. 
LEMNACEAE. 
SPIRODELA Schleid. 
219. Spdrodela polyrhiza (L.) Schleid. Greater Duckweed. Not com- 
mon in ponds. 
LEMNA L. 
220. Lemna trisulca L. Ivy-leaved Duckweed. Common in ponds and 
bayous. 
221. Lemna minor L. Lesser Duckweed. Less common. 
COMMELINACEAE. 
TRADESCANTIA (Rupp) L. 
222. Tradescantia reflexa Raf. Reflexed Spiderwort. Common, es- 
pecially in sandy soils. 
223. Tradescantia virginiana L. Spiderwort. Much less common, lo- 
cally. 
