100 Cheney and True—Flora of Madison and Vicinity. 
530. S. Candida , Willd. Sage willow. Hoary willow. 
In marsh lands about lakes. Common. 
531. S. myrtilloides, L. 
With S. Candida. Less common. 
PoPULTTS, Tourn. Poplar. Aspen. 
532. 
P. 
alba, L. White poplar. Abele. 
Occasional in cultivation. 
533. 
P. 
tremuloides , Michx. American aspen. 
Common in all the woods of the region. 
534. 
P. 
grandidentata , Michx. Large toothed aspen. 
With P. tremuloides. Not so common. 
535. 
P. 
balsamifera , L. Balsam-poplar. Tacamahac 
Cultivated as shade or ornamental tree. 
536. 
P. 
dilatata, Lombardy poplar. 
Cultivated in many places. 
MONOCOTYLEDONES. 
Hydrocharidace,®. (Frog’s-bit Family.) 
Elodea, Michx. Water-weed. 
537. E. Canadensis , Michx. ( Anacharis Canadensis , Plan- 
chon. ) 
Very abundant in most spring waters of the- 
region. Becoming a troublesome obstruction in 
many streams. 
Vallisneria, L. Tape grass. Eel grass. 
538. V. spiralis , L. 
Common in the shallow parts of the lakes. 
Orchid ace ae. (Orchis Family.) 
Aplectrum, Nutt. Putty-root. Adam-and-Eve. 
539. A. hiemale , Nutt. 
Rich woodlands east of Lake Mendota. Local. 
