Even this degree of antiquity is, however, much less than that of the Baobab trees of Africa, estimated by Adanson at 5150 years ; and the deciduous cypress of Chapultepec in Mexico, which the younger De Candolle considers still older.
The following list of old trees is from Moquin Tendon's Terato- logie V6getale : There are known Palms of . . . . . 200, 300 years.
Cereis 300 Chirodendron . . . . 327 Ulmus (Elm) . . 355 Cupressns (Cypress} . . . 388 Hedera (Ivy) . . . 448 Acer (Maple) . . . . 516 Larix (Larch) . . . 263, 576 Castanea (Chestnut). 360, 626 Citrus (Oranges, Lemons, &e.). . 400, 509, 640 Platanus (Pisne) . . . . 720 Cedilla (Cedar) . . . . 200, 800 Juglans (Walnut) . . . . 900, Tilia (Lime) . . . 364, 530, 800, 825, 1076 Abies (Spruce) . . . . 1200 Quereus (Oak) . . . . 600, 800, 360, 1000, 1600 Olea (Olive) . . . . . 700, 1000, 2000 Taxus (Yew) . . . . 1214, 1466, 2588, 2630 Schubertia . . . . . 3000, 4000 Legum inosa3 . . 2052, 4101 Adan.onia (Baobab) . . . 6000 Dracaena (Dragon Tree) . . 6000 The way in which the ago of some of these specimens has been com puted is twofold : firstly, by comparing them with other old specimens, the rate of growth of which is known ; and secondly, by cutting out a portion of their circumference, and counting the number of concentric rings that are visible. For in exogenous trees the woody cylinder of one year is divided from the succeeding one by a denser substance, which marks distinctly the line of separation of the two years.
In the course of inquiries into the method of computing the age of ancient trees, a discovery has been made of some importance to timber growers, inasmuch as it shows that those who plant for profit alone should not allow their trees to grow beyond a certain number of years, varying according to species for it has been found that so far are exogenous trees from continuing always to increase in diameter at the same rate, that every kind diminishes in its rate off growth after a certain age :the oak, for example, between its fortieth and its sixtieth year, the elm after its fiftieth, the spruce-fir after its fortieth, and the yew probably after its sixtieth. With reference to this subject, Pro fessor De Candolle has constructed a table, of rate of growth, which we subjoin.
Of ancient yews several authentic instances can be named. At Ankerwyke House, near Staines, is a yew older than the meeting of,the English barons at Runnymede, when they compelled King John to grant Magna Charts. This tree, at 3 feet from the ground, measures II feet 3 inches in diameter ; and its branches overshadow a circle of 207 feet in circumference. The yews of Fountains' Abbey, in Yorkshire, are probably more than 1200 years old, and to others an age of from 2,00 to 3000 years has been assigned.