PRINCIPAL GROUPS OF PLANTS. 103 



root system which serves the double purpose of absorbing nutri- 

 ment from the substratum or soil and holding or fixing the plant 

 in its upright position. The embryonal stem grows vertically 

 upwards, continuing its growth indefinitely. Lateral branches 

 arise at more or less regular intervals which extend from near the 

 ground to the apex, the younger branches continually succeeding 



FIG. 64. Bjrd's Nest Moss (Selaginella lepidophylla) . A, the plant growing in a 

 moist situation or upon the addition of water; B, the habit of the plant under dry conditions, 

 it unrolling and becoming as (A) upon the addition of water. This plant is also known 

 as Resurrection plant and Rose of Jericho, the latter name is more correctly applied to 

 Anastatica hierochuntica, a cruciferous plant of the East Mediterranean and Egypt, the 

 stems on drying becoming folded together and the whole plant being scattered by the wind. 

 The Bird's Nest Moss grows in Mexico and western Texas, and in the rolled-up condition 

 (B) is found occasionally in commerce and is used as a table decoration. It has the advan- 

 tage that even though it dries out, it may be renewed many times. After Hieronymus 

 in Engler and Prantl. 



the older ones from the ground upward, thus giving the trees 

 a cone-like outline. The leaves arise on the branches and are of 

 two kinds, primary leaves which are more or less scale-like and 

 deciduous, and secondary leaves which are true foliage leaves, 

 and are usually quite simple in structure. The leaves vary in 

 form but are usually narrow and somewhat thickened, giving 

 them a needle-like appearance. 



