108 Mr W. C. Crawford wi 



without whicli there cannot be richness of colour. I 

 doubt if even in their native Indian mountains they are 

 more gorgeously magnificent. 



On Phyto-Phenolofjical Observation. By W, C. Crawford. 



(Read 8th May 1884.) 



{Abstract.) 



The number of observations on the budding and flower- 

 ing of plants, the ripening of fruits and the like, in rela- 

 tion to climate and weather, yearly increases ; and an 

 attempt is being made in Germany to co-ordinate them 

 and give them a scientific value.* Phenological maps, 

 with lines in the fashion of isothermal lines to indicate the 

 places where vegetation is equally advanced at certain 

 dates, have also been published ; but little new knowledge, 

 apart from that indicated on an ordinary physical map, was 

 thus indicated.! Attention was directed to some very 

 careful researches of Professor Hoffmann of Giessen on the 

 flowering of plants, in which he analyses the phenomenon 

 into its separate factors, such as the mean temperature of 

 the air, sunshine, rainfall, temperature of the soil, &c. 

 He shows that the most important of these is underground 

 temperature. J To give these researches a local applica- 

 tion, the accompanying diagram has been constructed. In 

 it a graphic curve gives averages of the times of flowering 

 of forty plants in the Royal Botanic Garden, originally 

 chosen for observation b}' the late James M'Xab, and con- 

 tinued records of which have been accumulated by his 

 successors for ten years. II. 9, under 1882, means the 

 9th February, that being the mean of all the dates for the 

 year, when the first blossoms expanded. The other curve 

 is that of the mean underground temperature as given in 

 the Registrar General's reports for the same period. The 

 two curves run exactly parallel. Apparently, then, the 

 present methods of taking large averages from selected 

 yjlants, or general observations and records of the annual 

 progress of vegetation, are of little value, and afi'ord no 



* Bcitr(ege zur Phoenologie, Hoffmann und Ihne, Giessen, 1884. 

 t Petermann, Mitth., 1881, i. ; 1382, ix. 

 X Gartenflora, 1882. 



