214 



a height of about a hundred feet. What 

 a contrast with their descendants of 

 this age! 



Lepidodendron means "scale tree," 

 and this name was assigned these 

 plants since the bark on the trees was 

 covered with scales. Representatives of 

 this form are found as far back as 

 Devonian times. It was during the 

 Permian that their dominance gave 

 way. 



The trunks of Lepidodendrons, 

 some of which were four feet or more 

 in diameter (and which grew to a 

 height of a hundred feet or more), 

 were straight and palm-like, and bore 

 toward the top a crown of branches. 

 The stems were clothed in long simple 

 leaves which, being needle-like, resem- 

 bled roughly those of the pine. In some 

 forms the needle leaves attained a 

 length of six or seven inches. The tips 

 of the slender branches bore cones 

 which sometimes reached a length of 

 20 inches and a diameter of 2 inches. 

 There were huge underground parts, 

 very much like roots in appearance, 

 but without the structure of roots, to 

 which the name Stigmaria has been 

 applied. These root-like structures are 

 marked with circular scars where the 

 "rootlets" were attached. These root- 

 like organs were possessed both by 

 Lepidodendron and the closely allied 

 form, Sigillaria. 



Sigillarias were also found along 

 with the Lepidodendrons. The word 

 Sigillaria means "sealtrce" and is ap- 

 propriate because the impressions on 

 the bark frequently resemble the wax 

 seals which were used by our fore- 

 fathers to close their letters. Like the 

 Lepidodendrons, these trees attained 

 a great size but most of them were un- 

 branched. There are accounts of some 

 of these trees that were only 18 feet 

 in height but were 6 feet in diameter. 

 The leaves were varied in size, some 

 resembling closely those of the Lepido- 



PALEOBOTANY 



dendrons, while others were long and 

 sword-shaped being three feet long. 

 Sigillarias bore their cones in vertical 

 rows or in a whorl about the stem and 

 the cones were usually much smaller 

 that those of the Lepidodendron cones. 

 The propagation of both of these 

 trees was accomphshcd by means of 

 spores. Quantities of big spores are 

 found in coal, and naturally enormous 

 masses must have been shed in the 

 swamps where coal was formed; but 

 only a few, relatively speaking, ever 

 germinated. Tlie first food of the em- 

 br\'onic plant was contained in the 

 spores, hence they were rich in oils 

 and other fats. The coal made up of I 

 these spores is oily and is commonly I 

 referred to as "cannel coal." " 



PTEROPSIDA 



In this category we place the true 

 ferns, the gymnosperms and the angio- 

 sperms. The true ferns trace their his- 

 tory back to the middle of the Devo- 

 nian period. They increased in species 

 and numbers of individuals during the 

 Carboniferous period. During the Ju- 

 rassic they showed some tendency to 

 decline but they are apparently "hold- 

 ing their own" with some 10,000 

 species known. 



Fossil g}'mnosperms may be illus- 

 trated by the Pteridosperms and the 

 Cordaitales. The first group was char- 

 acterized by fern-like foliage but they 

 were true seed plants. Some of them 

 grew to 60 or 70 feet in height and 

 had trunks with diameters of about 

 two feet. The Cordaitales includes 

 several groups. One of these groups 

 contains the genus Cordaites. Tlie 

 genus was very common in the Car- 

 boniferous period. Tlie slender leaves 

 frequentlv were three feet in length, 

 the stem had sccondar)' wood and a 

 pith and the male and female inflo- 

 rescences were in the form of strobili. 



