326 TIEWS, &C. PHYSIOGNOMY OP PLANTS. 



These are, as Link correctly observes,* transitions to Lede- 

 bour's P. sibirica of the Altai. 



The delicate and pleasing green though deciduous foliage 

 of the Ahuahuete (Taxodium distichum, Rich., Cupressus dis- 

 ticha, Linn.) on the Mexican plateau especially delighted 

 me. In this tropical region the tree, swelling out to a portly 

 bulk, and the Aztec name of which signifies " water-drum. " 

 (from atl, water, and huehuetl, drum), flourishes from 5750 

 to 7670 above the level of the sea, whilst it descends 

 towards the plain in the marshy district (Cypress swamps) 

 of Louisiana as far as 43 lat. In the southern States 

 of North America the Taxodium distichum ( Cypres chauve\ 

 as well as in the lofty plains of Mexico, attains a height of 

 128 feet, with an enormous girth, the diameter being from 

 30 to nearly 40 feet, when measured near the ground.f The 

 roots, too, present a very remarkable phenomenon, for they 

 have woody excrescences, which are sometimes of a conical 

 and rounded, sometimes of a tabular shape, and project three 

 and even nearly five feet above the ground. Travellers have 

 compared these woody excrescences, in spots where they are 

 numerous and frequent, to the grave-tablets of a Jewish 

 churchyard. Auguste de St. Hilaire remarks, with much 

 acuteness: "These excrescences of the bald cypress, which 

 resemble boundary-posts, may be regarded as exostoses, and 

 like these live in the air; adventitious buds would doubtless 

 escape from them, if the nature of the tissue of the coniferous 

 plants did not oppose itself to the development of those con- 

 cealed germs that give birth to these kinds of buds.";]; In 

 addition to the above, a remarkably enduring vitality is mani- 

 fested in the roots of cone-bearing trees by the phenomenon 

 which, under the name of " Effervescence," (aftergrowth?) has 

 attracted, in many ways, the attention of botanical physiologists, 

 and which phenomenon, it appears, rarely displays itself in other 

 dicotyledonous plants. The stumps of the felled white Pine r 

 left in the ground, form, during a succession of several years, 

 new layers of wood, and continue to increase in thickness, 

 without throwing out shoots, branches, or leaves. The excel- 

 lent observer Goppert believes, that this takes place solely 



* Linncea, bd. xv. 1841, s. 489. 



f Emerson, Report on the Forests, pp. 49, 101. 



J Morphologie vegetale, p. 91. 



