204 



De Candolles Essay 



[April, 



genous trees depends on their thickness. It is necessary then in the first place 

 to recommend travellers to note exactly the circumference of the trunk of every 

 species of palm. It should also he required of them to determine the height of 

 palms of every species, and to decide from observation, whether the rings visible 

 on the exterior really indicate, as is asserted, the annual growth, or any other de- 

 finite period. 



The first method applied to the Date-palm appears to give results which are con- 

 formable to truth. Thus in 1809, at Cavalaire, in Provence, a date was known that 

 had been sown in 1709 ; it was then 50 feet high ; the greatest height of those 

 of Egypt and Barbary., is 6'0 feet, and the Arabs consider their longest life to be 

 from 200 to 300 years. It would be necessary to ascertain in what proportions 

 the rapidity of growth decreases at different periods. 



By allowing that the rings on the outside of the trunk mark the years, the 

 approximate age of the palms of Brazil might be discovered according to the prin- 

 ciples furnished by M. de Martius, in his magnificent work, as follows : 



(Enocarpus Batavia 

 Euterpe oleracea 

 Euterpe edulis. 

 Iriartea exorhiza. . . 

 Gulielma speciosa. . 



Cocos olea'acea 



Cocos nucifera 



Height of 

 trunk. 



feet. 

 80 



120 



100 

 80 to 100 

 80 to 90 

 60 to 80 

 60 to 80 



Diameter of 

 trunks. 



inches. 



12 

 8 at 9 

 6 at 7 



12 

 6 at 8 



12 

 4 at 12 



Distance of 

 Rings. 



Probable age. 



inches. 



7 

 4 at 

 4 at 

 4 at 

 4 at 

 1 at 



3 at 12 



years. 



134 



300 



300 



250 to 300 



250 to 300 



600 to 700 



80 to 233 



I give these approximations to travellers as mere indications, and to induce them 

 to verify my theory. 



As to indogenous trees, which are covered with branches, and are without regular 

 rings, no means have yet been discovered by which to calculate their age, and the 

 entire problem must be left for the solution of local observers. It is known that 

 some trees belonging to this class live to a very great age ; such is the celebrated 

 Dragon-tree (Dracaena draco) in the garden Franchi at Orotava, in the Island of 

 Teneriffe, which was considered remarkable in 1402, at the time of the discovery 

 of the island, and which was even then an object of veneration to the people. Mr. 

 Berthelot (Mem. cur. Nat. vol. 13, p. 781,) who has published a good description 

 of this tree, says that in comparing the young neighbouring Dragonniers with this 

 giant tree, the calculations which he had made regarding the age of the latter 

 have more than once astonished him. In 1797, according to M. Ledru, it was 

 65 feet in height, 42 in .circumference at the middle, and 78 at the bottom. Since 

 then the hurricane of the 21st July, 1819, has reduced its height very much. 



I am inclined to believe that among the perennial grasses and the shrubs there 

 are many much older than they are generally believed to be, but no inquiry has been 

 made on this subject. I may cite a few imperfect facts, which may lead observers 

 to turn their attention to the duration of life in these humble plants. I mentioned, 

 in my work on the Organography of Vegetables, the " herbaceous willow," which 

 growing on the thin soil of the Alpine rocks, at the feet of a declivity, gradually 

 lengthens its stem as the earth fills up, so as just to enable it to shew its head above 

 the soil, the top of the tree resembling a grass-plot of several yards diameter. I 

 have tried to lay open the stem of this singular tree, but I never could reach its 

 base : the length laid bare, compared with the extreme slowness of its growth, 

 already indicated a very advanced age. 



