224 BOTANY. 



tree-ferns. They are of slow growth and are long-lived; 

 the stem elongates by a slowly unfolding terminal bud, 

 which gives rise to a crown of widely spreading pinnate 

 leaves, which are constantly renewed above as they die and 

 fall away below. About seventy-five species are now 

 known, all confined to tropical or sub-tropical climates. In 

 geologic times (Triassic and Jurassic) they were very abun- 

 dant. 



473. The Conifers ( Order OoniferoR) are mostly trees of 

 a considerable size, with branching, spreading, or spiry 

 tops, as the pines, spruces, firs, etc. etc. They are gener- 

 ally of rapid growth, and in many cases attain a great 

 height and diameter. In the greater number of species the 

 leaves are persistent, and the trees, consequently, evergreen. 



474. The order contains thirty-two genera and about 

 three hundred species, which are distributed mainly in the 

 cooler climates of the globe. Seventy or more species 

 occur within the limits of the United States, and constitute 

 in many places enormous forests hundreds of miles in ex- 

 tent. 



The pines (Pinus) include tlie most important trees of the order. 

 The White pine (P. slrobus), formerly very abundant from the Great 

 Lakes eastward, f urnislies the greater part of the "pine lumber" so 

 largely used in the Northern States for building and other purposes. 

 The Sugar-pine (P. lambertiana) of California resembles the White 

 pine but is much larger, being often 60 to 90 metres (200 to 300 feet) 

 in height, with a trunk 3 to 6 metres (10 to 20 feet) in diameter. The 

 Southern pine (P. australis), abundant from the Carolinas to Texas, is 

 a tree of moderate dimensions, whose hard wood is ' ' superior to that 

 of any other North American pine," and is known in the markets as 

 Yellow or Georgia pine. Scotch pine (P. sylvestris) and Austrian 

 pine (P. liiricio), both natives of Europe, are extensively planted in 

 this country. Besides the spruces, firs, larches, cedars, and many 

 other well-known trees, the order contains the two species of great 

 Redwoods. The moat remarkable is called the Big Tree (Sequoia 



