INVENTORY OF SEEDS AND PLANTS IMPORTED BY 

 THE OFFICE OF FOREIGN SEED AND PLANT IN- 

 TRODUCTION DURING THE PERIOD FROM OCTO- 

 BER 1 TO DECEMBER 31, 1922 (NO. 73; NOS. 55814 

 TO 56144) 



INTRODUCTORY STATEMENT 



To many it may not be apparent why the Province of Yunnan, 

 which borders Tibet on China's western boundary, is a particularly 

 likely place to search for plants for introduction into America. 



Mr. Rock, our agricultural explorer, who has been collecting in 

 this region now for nearly three years, shows by his notes and 

 specimens in what way Yunnan plants are likely to be valuable to 

 American horticulture. 



The vast mountain area, in which he has been exploring, where 

 snow-clad peaks 12,000 to 20,000 feet high rise from almost sub- 

 tropical valleys and gorges thousands of feet deep have been 

 channeled by the largest and longest rivers in Asia (the Mekong and 

 the Yangtze) in their break through the mountains which bound the 

 Tibetan table-land, furnishes a home for thousands of interesting 

 plants which some day will enrich our horticulture. 



It is true that other exploring botanists, like Forrest and Kingdon 

 Ward, have visited it, but this is the first time that an American 

 explorer, with the needs of our farms and gardens in mind, has 

 hunted for plants which can be grown in American dooryards and 

 has entered western China by its back door, so to speak, which is 

 Bhamo, on the border of Burma. 



Mr. Rock's itinerary, like that of Frank Meyer, will be given in 

 detail in a later number of this series. It suffices for him to 

 locate the region where he collected the plants in this inventory. 

 This centers chiefly around Likiang and the Likiang Snow Range. 

 Many of the plants were found in localities where the thermometer 

 goes below 32° F. and heavy snowfalls occur. High tropical altitudes 

 and temperate-region latitudes correspond, but only roughly so, for 

 it has come to be well recognized that high alpine plants are ac- 

 commodated to conditions which do not prevail at many places at 

 sea level in the Temperate Zone, The heavy and continuous blanket 

 of snow which characterizes many mountain regions makes it pos- 

 sible for many rather tender plants, such as the potato, for example, 

 to live in the ground over winter. To illustrate, in the higher al- 

 titudes of the Rockies on its western slopes and also as far north 

 as Cape Breton Island, Nova Scotia, potato tubers often remain 

 unfrozen in the soil because the soil is blanketed with snow before 

 freezing weather occurs, whereas otherwise they would be frozen in 



