100 
IOWA ACADEMY OF SCIENCES. 
THE LIMITS OF CULTIVATED PLANTS. 
Some of the cultivated plants, especially the forage 
plants, have been widely naturalized. Trifolium pratense, 
T. rei[)ens, Phleum prate7ise and Poa pratensis have followed 
the trails far beyond present limits of the cultivated areas. 
The clovers are found miles beyond the settlements. Fre- 
quently along old trails or wdiere lumbering operations 
were formerly carried on. Fruit culture is successful in 
the Bitter Boot Valley and its tributaries up to altitudes 
somewhat above 4,000 feet. Orchards have been planted 
where frosts occur nearly every w^eek in the year. The 
culture of the potato occurs at altitudes somewhat higher 
than the apple. Cherries (P^uinus cerasus), P^ninus domes- 
tica and Peaches succeed in the Bitter Root Valley. 
