342 .PHYSIOGNOMY OF PLANTS. 



direction through eighty degrees of longitude (above 3040 geogra- 

 phical miles), from the mouth of the Scheldt through Europe and 

 the north of Asia to Bogoslowsk in the northern Ural and Barnaul 

 beyond the Obi, I have found differences in the length of the needles 

 of our common Fir (Pinus sylvestris) so great, that sometimes a tra- 

 veller may be misled, by the shortness and rigidity of the leaves, to 

 think that he has discovered a new species allied to the Mountain 

 Pine, P. rotundata (Link), P. uncinata (Ram.). Link has justly 

 remarked (Linnsea, bd. xv. 1841, s. 489) that such instances may 

 be regarded as transitions to Ledebour's P. sibirica of the Altai. 



,In the Mexican highlands, I have looked with particular pleasure 

 on the delicate cheerful green of the Ahuahuete, Taxodium dis- 

 tichum (Rich.), Cupressus disticha (Linn.), which, however, is 

 much given to shedding its leaves. In this tropical region, the 

 above-mentioned tree (of which the Aztec name signifies water- 

 drum, from ail, water, and Imeliueil, a drum, the trunk swelling to 

 a great thickness) nourishes 5400 and 7200 (5755 and 7673 Eng- 

 lish) feet above the level of the sea; while in the United States of 

 North America it is found in the low grounds of the cypress swamps 

 of Louisiana, in the 43d parallel. In the Southern States of North 

 America, the Taxodium distichum (Cypres chauve) reaches, as in the 

 Mexican highlands, the height of 120 (128 English) feet, and the 

 enormous thickness of 30 to 37 (32 to 39 English) feet, measured 

 near the ground. (Emerson, Report on the JForest, pp. 49 and 

 101.) The roots present the striking phenomenon of woody excres- 

 cences which project from 3 to 4 feet above the earth, and are coni- 

 cal and rounded, and sometimes tabular. Travellers have compared 

 these excrescences in places where they are very numerous to the 

 grave tablets in a Jewish burying-ground. Auguste de St. Hilaire 

 remarks with much acuteness : \ < l CeS excroissances du Cypres 

 chauve, ressemblant a des bornes, peuvent etre regarde"es comme des 

 exostoses, et comme elles vivent dans 1'air, il s'en echapperoit sans 

 doute des bourgeons adventifs, si la nature . du tissu des plantes 

 coniferes , ne s'opposoit au de"veloppement des germes caches qui 

 donnent naissance a ces sortes de bourgeons." (Morphologic vge- 

 table, p. 91.) A singularly enduring power of vitality in the roots of 

 trees of this family is shown by a phenomenon which has excited the 



