278 PHYLUM XIII. STROBILOPHYTA 



long-lived tree, rooted below, and bearing green (mostly 

 perennial) leaves above. 



499. Since the sporophytes are large and long-lived 

 their tissues are many and well-developed. Their 

 tracheary tissue is almost wholly of the form known as 

 tracheids, which are here marked on their radial faces 

 with bordered pits. Proper fibrous tissue is scanty or 

 wanting. The vascular bundles are of the open collateral 

 type, arranged in a cylinder so that they provide for 

 increasing the diameter of the stems and roots. Turpen- 

 tine canals are present in all parts of the plant. 



600. There are nine families of conifers, a few only of 

 which need be noticed here. In all the microspore cones 

 are well developed, but there is a gradual simplification 

 of the megaspore cones from those with many sporo- 

 phylls to those with few or one. The Taxodiums (Family 

 Taxodiaceae). Microsporophylls with two to eight spor- 

 angia: megasporophylls woody, much en- 

 larged distally, bearing two to several erect 

 or inverted seeds, forming compact, ellipsoid 

 cones; "seed scale" wanting. Here are the 



Sequoia (seed- Bald Cypresses (Taxodium) and Redwoods 

 (Sequoia), very old types that originated in 

 the Mesozoic, and have persisted with reduced numbers 

 to the present. The Redwoods, now confined to the 

 mountains of California, were once widely distributed 

 in the Northern Hemisphere. 



601. The Old Pines (Family Araucariaceae) . Micro- 

 sporophylls with five to fifteen spor- 

 angia: megasporophylls woody, slightly 



enlarged distally, bearing one inverted 



seed, forming compact spheroidal cones; FIG. 154. Arauca- 



i i T mi /~vi ria (seed-cone). 



seed scale" rudimentary. The Old 

 Pines are now confined to the Southern Hemisphere, and 



