420 joruxAL OF forestry 



On the whole, manna gum proved to be the most frost-resistant 

 eucalyptus in southern California. For a time it was thought to be the 

 only eucalyptus species which had not been killed, though, as subse- 

 quent results have shown, but few others were seriously damaged. 



Eucalyptus tereticornis Sm. Gray Gum 



Large mature trees of gray gum recovered quickly. Most of the new 

 growth was normal, though a number of specimens showed sprouts. 

 A majority of the mature trees were heavily defoliated, but as no, wood 

 was killed the trees exhibited no sign of frost injury. In young planta- 

 tions the effect was different. Wood of last season's growth was partly 

 killed, while the trees were entirely defoliated. New growth started 

 largely from adventitious shoots. These usually occurred in large 

 clusters. They appeared on the stem, as a rule, at least 8 inches above 

 ground, even in one-year-old trees. 



Coppice of the gray gum two years old was killed back to the stump, 

 from which new sprouts put forth. Older coppice was not affected as 

 seriously, though the crowns were defoliated. Trees cut after the 

 freeze coppiced freely, both from the stump and from the root collar. 



In general, the tree endured the low temperatures without much 

 injury. 



Eucalyptus coriacea A. Cunn. Drooping Gum 



The drooping gum is one of the least known eucalypts in southern 

 California. As far as can be ascertained, the only specimens of this 

 tree are in the Forest Service plantation of 1909, at Del Rosa, near San 

 Bernardino. Here there are about 60 trees, situated in the canyon of 

 the Little Sand Creek. While temperatures about Del Rosa reached 

 the low mark of 14 degrees, residents nearer the foothills reported 

 temperatures of 11 degrees and 12 degrees, and it is certain that this 

 canyon was colder than some of the protected orange groves farther 

 out in the San Bernardino Valley. 



In this plantation none of the plants were killed by the severe cold, 

 but the majority of them show slightly injured leaves. On a few trees 

 nearly all the leaves had been killed, though even here there were leaves 

 entirely unaffected by the cold. About 40 per cent of the plantation 

 shows no sign of injury whatever. The regular spring growth was in 

 progress 10 weeks after the freeze. At this time the young leaves were 

 green and the trees were making a fast and vigorous growth. One 

 tree developed adventitious shoots on a small branch and three others 

 sprouted from the root collar. Of 13 species of eucalyptus in this 

 canyon, the drooping gum showed the least sign of injury. 



