CLASS MON0EC1A. 197 



leaves are solitary, and distinct at the base. Our com- 

 monest species is A. canadensis, called the Hemlock 

 or Spruce tree, which has the leaves nearly in two 

 rows, flat and denticulate ; the cones ovate, terminal, 

 and scarcely longer than the leaves. The A. balsamea, 

 or Balsam Fir, has, also, flat, emarginate, or entire 

 leaves, glaucous (or bluish green) beneath, arranged 

 in several rows, recurvedly spreading ; the cones large, 

 purplish, cylindric, and erect. This very ornamental 

 tree, so common in the northern states, extends by the 

 Alleghany mountains as far as North Carolina, and is 

 also found in the Rocky mountains towards the sources 

 of the Missouri. It is scarcely distinct from the A. 

 picea of Europe, and is very nearly related to the P. 

 sptciosa of the Hymalaya mountains, near the sources 

 of the Ganges. The Canada Balsam is obtained from 

 resinous blisters, which are pierced, and occupy the 

 trunk of the tree. The leaves are remarkable for their 

 persistence, adhering to the branches for several years. 

 In the true Pines (Pinus) the leaves narrow, long, 

 and needle-formed, occur from 2 to 5 in a short cylin- 

 drical sheath ; but in most of them the primordial 

 leaves are solitary, and without sheathes, as in Abies. 

 The clustered leaves of this section may then perhaps 

 be considered, as they are in Larix or the Larch, 

 minute branchlets, each, at first, enveloped like the 

 larger buds with imbricated appropriate scales. All 

 the species germinate with more than 2 seed-leaves, 

 (from 3 to 8), a peculiarity unknown in any other fam- 

 ily of plants. The species nearest related to the pre- 

 ceding section is the Pinus strobus (White or Wey- 

 mouth Pine), readily known from every other Ameri- 

 can species by its slender leaves in 5's, and pendulous 

 cylindrical cones, longer than the leaves, with loose 

 scales. The Hymalaya mountains likewise afford a 

 species very similar to the Strobus, P. exceka. One 

 17* 



