§ CIRCULAR 447, U. S. DEPARTMENT OF AGRICULTURE 



POTATOES 



Freezing-point determinations were made on 13 different com- 

 mercial varieties of potatoes. 



SWEETPOTATOES 



The results of freezing 17 more or less common varieties of sweet- 

 potatoes are presented in table 3. The variety with the lowest 

 freezing point was Mullihan, one of the less known varieties, which 

 froze at 27.6° F. The highest freezing points were found with 

 Pumpkin and Yellow Jersey varieties, both of which froze at 29.0°. 



TOMATOES 



The freezing-point temperatures of 17 commercially grown varieties 

 of tomatoes are presented in table 3. These tomatoes were all 

 grown under the same conditions at Arlington Farm. Determina- 

 tions were made on both field-ripened and mature-green tomatoes 

 such as are usually shipped to distant markets. The lowest freezing 

 point (29.8° F.) of ripe tomatoes was found in the New Glory variety. 

 The Marglobe and Livingston Acme varieties both froze at 30.7°, the 

 highest freezing point in any of the varieties studied. There was no 

 difference in the average freezing points of ripe and mature green 

 tomatoes. 



SWEET CORN 



Four varieties of sweet corn were studied, all in the milk stage. 

 The freezing point varied considerably with the age of the product, 

 and there was also considerable variation among varieties (table 3). 



MISCELLANEOUS VEGETABLES 



The freezing points of three varieties of onions, four of lettuce, two 

 of carrots, two of cantaloups, two of watermelons, and three of peas 

 are also given in table 3. The freezing points of several other kinds of 

 vegetables where only one variety of each was studied are given in 

 table 4, together with the average freezing point of all of the vegetables 

 listed by varieties in table 3. 



FREEZING POINTS OF FLORISTS' STOCKS 



The freezing points of cut flowers, plants, bulbs, corms, and tubers 

 that are commonly held in cold storage or shipped in quantities were 

 similarly determined. The determinations made for 15 kinds of cut 

 flowers, S of bulbs, corms, and tubers, and 10 of plants are presented 

 in table 5. The freezing points of cut flowers were determined on 

 petals alone, and of plants on leaves alone. The freezing points of the 

 petals of cut flowers varied from 27.5° F. in Easter lilies to 30.8° in the 

 orchid. The leaves of rose and peony plants froze at lower tempera- 

 tures than petals borne on the same stems, whereas leaves of Easter 

 lilies froze at a higher temperature than the petals. The fronds of 

 dagger ferns, which are commonly shipped in large quantities and 

 stored during the winter, froze at the relatively low temperature of 

 23.6°. Holly leaves such as are used in large quantities in sprays or 

 wreaths for Christmas decoration froze at 26.3°. The foliage of 

 neither holly nor dagger fern was apparently injured by freezing, as is 

 often the case with less hardy plant material. Asparagus ylumosus 

 foliage, which is shipped in considerable quantities, also froze at a 

 relatively low temperature, 24.2°. The leaves of sansevieria plants, 

 which are frequently shipped in large quantities for potting as orna- 

 mentals froze at the relatively high temperature of 31.0°. Among the 



