HEAT OF THE ARUM. 85 



ynder a colder sky than is natural to them. But many 

 alpine plants, naturally buried for months under a deep 

 snow, are not only extremely impatient of sharp frosts, 

 but will not bear the least portion of artificial heat. The 

 pretty Primula maj'ginata^ Curt, Mag. t. 191, if 

 brought into a room with a fire when beginning to blos- 

 som, never opens another bud ; while the American 

 Cowslip, Dodecatheon Meadia, t. 12, one of the most 

 hardy of plants with respect to cold, bears forcing ad- 

 mirably well. 



Mr. Knight very satisfactorily shows, Phil. Trans. 

 for 1801, 343, that plants acquire habits vvuh regard. to 

 heat which prove their vitality, and that a forced Peach- 

 tree will in the following season expand its buds pre- 

 maturely in the open air, so as to expose them to inev- 

 itable destruction. See p. 65. A thousand parallel 

 instances may be observed, by the sagacious gardener, 

 of plants retaining the habits of their native climates, 

 which very often proves one of the greatest impediments 

 to their successful cultivation. 



The most remarkable account that has fallen in my 

 way concerning the production of heat in plants, is that 

 given by Lamarck in his Flore Frangoise^ v. 3. 538, of 

 the common Jrum maculatum, Engl. Pot. t. 1298, 

 (the white-veined variety,) the flower of which, at a cer- 

 tain period of its growth, he asserts to be, for a few hours, 

 " so hot as to seem burning." The learned M. Sene- 

 bier of Geneva, examining into this fact, discovered 

 that the heat began when the sheath was about to open, 

 and the cylindrical body within just peeping forth : and 

 that it was percept! 'ole from about three or four o'clock 



