257 



The common polypody abounds on the hirj^er rocks, especially 

 on their shaded sides, and a few clumps of the marginal shield 

 fern grow at the bases of these rocks. Solidago Curlisii and two 

 species of blue gentian were fairly common, and a number of 

 other herbaceous plants might be selected in the sj^ring or early 

 summer, when they are in flower. 



SNOW INJURY TO TREES 



By George B. Rigg 



During the winter and spring of 1915-16 the writer has been 

 interested in observing the effects of the unusual climatic con- 

 ditions on the native trees of the Puget Sound region occurring 

 at or near sea-level, particularly the relative amount of mechan- 

 ical injury by snow to needle-leaf evergreens and broad-leaf 

 evergreens. 



Although the minimum temperatures of this winter were low 

 and the cold spells were prolonged,* there was not a great deal of 

 serious injury to evergreens from this source. A good many 

 individuals of Douglas fir {Pseudotsuga taxifoUa), Madrona 

 (Arbukcs Menziesii) and sticky Laurel {Ceanothus velutinus) 

 show more than the usual number of dead leaves, but this does 

 not seem to have interfered seriously with their growth although 

 a few dead Madronas have been reported. The following facts 

 indicate that the winter was a time of relatively severe cold. 

 The minimum temperature was +14° F. on January 11 and the 

 same on January 29, A cold spell began on December 29 and 

 lasted with two slight breaks until February 5. The minimum 

 temperature was below 32° F. many of the days, and from 3 A.M. 

 January 10 to i P.M. January 15 the temperature never rose to 

 32° F. The minimum temperatures of other severe winters 

 were as follows: -f3° F. on January 31, 1893; -}-i2° F. on Feb- 

 ruary 3, 1899; +13° F. on January 25, 1902; -f-ii° on Janury 15, 

 1907; and -f-i2° on January 13, 1909. 



The snow fall in the lowlands of the Puget Sound region is 



usually very slight. During many of the winters there is not 



* Weather data furnished by G. N. Salisbury-, director of Washington Section, 

 U. S. Weather Bureau. 



