2108 ARBORETUM AND FRUTICETUM. PARI' III. 



of a character anomalous to that of the /ibietina? in general. This anoma- 

 lous character will he illustrated by the portraits of a silver fir, and some 

 spruce firs, which we shall give in a future page. 



The bark of the Jbietinae is thin in 3'oung trees ; and, in some species of 

 yl'bies and PIcea, even in old trees, it is never cither very thick, or vtry 

 rough. In many species of Pinus, on the contrary, it becomes very thick, 

 rigid, cracked, and deeply furrowed in old trees, from the trunks of which it 

 may be cut in large plates. 



The wood is chiefly composed of parallel fibres, arranged in a manner 

 somewhat intermediate between that of dicotyledonous and nionocotyle- 

 donous trees ; and, in consequence of these fibres not being very close, the 

 wood is elastic and resilient. Being resinous, it is also, in general, very 

 durable, and of great combustibility. Michaux remarks that "the branches of 

 resinous trees consist almost wholly of wood of whicii the organisation is 

 even more perfect than it is in the body of the tree, and that the reverse is 

 the case with trees having deciduous leaves. As soon as vegetation ceases in 

 any part of the tree, the consistence of the wood speedily changes; the sap 

 decays ; and the heart, already impregnated with resinous juice, l)ecomes sur- 

 charged to such a degree as to double its weight in a year. The accumulation 

 is said to be much greater after 4 or 5 years ; the general fact may be proved 

 by comparing the wood of trees recently felled, with that of others long since 

 dead." (A''. Amer. Si)l.,\i\. p. 143.) 



The leaves are, in almost every case, linear, subulate, acicular, and per- 

 sistent ; thougii in Cunninghams they are lanceolate, and in Dinnvinra oblong. 

 In some species they remain on for four or five years, and, in Araucdria, 

 for ten or twelve years. In only one genus {IAr\\) are they deciduous. 

 In Pinus, Z,arix, and C^drus, they are placed together in bundles of from 

 2 to 6 in a bundle ; but in J^bies and Picea the leaves are single. Where 

 the leaves are in bundles, they are considered by botanists as abortive 

 shoots; because the rudhnents of a shoot are found at the base of the 

 leaves : and hence, in pine plants of only one or two years' growth from the 

 seed, the leaves arc solitary ; and it is only in the third or fomth year 

 that in the axils of these solitary leaves small short shoots appear, 

 each terminating in a fasciculus of from 2 to 6 leaves. The leaves of 

 all the species are without stipules ; the numerous scales which arc 

 found among them when the shoots are newly developed, being considered 

 as belonging to the buds. In Pinus, the leaves are in general more than 

 double the length of those of the other genera; the shortest, as in P. sylvestris, 

 being from liin. to 2 in. long; while those of P. Pinaster are from 6 in. to 

 9 in. in length, and those of P. australis Alkhx. arc from 1 ft. to H ft. In 

 all the other genera, the leaves are not much longer than half an inch ; and 

 very rarely, as in Picea Webbw/w, exceed an inch. The long-leaved species 

 belong to warm climates ; and these, when grown in cold climates, have their 

 leaves considerably shortened. In texture, the leaves are harcl and cori- 

 aceous, as in the case of most evergreens; but those of Larix form an excep- 

 tion. The leaves, in all the species, are without lateral nerves; and they are 

 composed of parallel fibres, like those of the Monocotyledoneae. 



The buds are enclosed in numerous scales, and are developed in the axils of 

 the leaves, or at the extreme points of the shoots. In all the s[)ecies they are 

 very few in number, compared with those of broad-leaved trees, in which there 

 is a bud either developed, or in embryo, at the base of every leaf. In the 

 Jbietinae on the other hand, there is not one bud for a million of leaves ; 

 and the few tliat are found in the axils are almost confined to the genera 

 yrbies, Picea, JLarix, and C'edrus. The buds are most numerous in Lkm, 

 and least so in Pinus, in which last genus they are almost entirely confined 

 to the points of the shoots. In general, the bud which terminates the summit 

 of the tree, and is destined to form its leading shoot, and increase its height, 

 is developed the last ; and this retardation seems a provision of nature for the 

 safety of the most important shoot which the tree can produce ; thus in- 



