566 



CORRELATION OF DISTRIBUTIONAL FEATURES. 



tives of a genus of Ranunculacese which is found elsewhere only in 

 eastern Asia. They are herbaceous root-perennials of moist situa- 

 tions, and neither of them is common nor characteristic of very exten- 

 sive plant communities. The ranges of both the eastern and western 

 species are based on a very small number of known localities of occur- 

 rence, and are so broadly drawn that they comprise climatological 

 stations near which the plants are doubtless absent. Here, as in many 

 other cases, a much more detailed study should be given to the dis- 

 tribution of the plants involved and to the nature of the climatic condi- 

 tions before attempting to apply the methods of a general study of this 

 character to an investigation of the climatic controls involved. It is, 

 nevertheless, of interest to make even a broad comparison between 

 the conditions under which these related but geographically segregated 

 species exist. 



The amphtude of the climatic conditions for the area of Traut- 

 vetteria grandis is wider than for that of T. carolinensis in all cases 

 except the number of hot days, physiological summation, and the 

 number of days in the longest normal rainy period. The former 

 species exhibits a very narrow range in number of hot days, from on 

 the coast of Washington to 57 at Sante Fe, New Mexico (near one of 

 the southernmost stations for the plant in the Sante Fe Mountains). 

 This condition appears to be an important one in determining the 

 limits of the western species. Trautvetteria carolinensis encounters 

 from 63 to 160 hot days, and also has a relatively narrow amplitude of 

 conditions with respect to the length of the frostless season, 145 to 

 231 days. 



The amplitudes of the daily mean precipitation and of the mean 

 annual precipitation are much narrower for Trautvetteria carolinensis 



TlHKRftTWM 

 0*va in Noitaiti nM«nna CtMOM (f . SJ 

 HotDat*. r. s. 



cotD DAT*, r. s. 



Pmtwolooicai. SumuTMN, f. 8. 



NoDit*!. Oaiit Mian. coiocaT 14 Mtt* or ium 



NoHMAL Daily Mian, Viam 



PRCCmTATION 

 NOMMAL OAILT MCAH, F. S. 



Oats in longest Noiimal Raint Pcrioo, F. S. 

 Oat* in lonsist Normal Dnt Piriod, F. 8. 

 McAN Total. Vur 



Evaporation 

 Oailt Mun. 18S7>8, F. 8. 



MoiRTURi Ratio* 

 Normal P/C. F. S. 

 Normal fr/E, F. 8. 

 Normal P/t. Yua 



Humidity 

 Normal Mian, F. 8. 



sumrhine 

 Normal Daily Duration, F. 8. 



MolSTURC-TCMPCRATURK INDICM 



Normal P/E i T, F. S.. Pmyriolocical MmtOD 



Fig. 72. Climati 



c extremes for Trautvetteria carolinensis. 



