ACROGENS FINISHED. 



41 



foliage-spray, which is broad, flat, and yery delicate. Some 

 of tiiera are rosulate, and never rooted ; these are the Bird's- 

 Nest Mosses of florists (S. cuspidata, called also Lycopodium 

 circinata). They are never fairly rooted ; they curl up into 

 a ball when dry, keeping their vitality, however, though 

 driven by the winds for miles over sandy wastes in the 

 dry seasons of the tropical countries in which they abound. 

 In moist weather they cling with their small rootlets to 

 the light sand or soil, unfold tlieir 

 leaves, and continue their life of 

 vegetation and reproduction. One of 

 these is the curious Resurrection Rose 

 (Selaginella lepidophylla) of the South- 

 western United States and Mexico. 



72. Though the growth in Acro- 

 gens is still cellular, wood-bundles 

 occur. These are not definite in form, 

 however; they appear near the cir- 

 cumference, as in the Tree- Fern (Fig. 

 42). There is no true bark ; the thick 

 rind is composed of the persistent bases of fallen leaves. 

 Observe four characteristics : 



/. Spores covered; Embryo still a simple cell without 

 diflerentiation into parts ; 



II. Flowers (Archegonium and Antheridium) still rudi- 

 mentary and microscopic ; 



III. Fronds and Leaves fork- veined (Fern, Marsilea), or 

 subulate (Moss, Club-Moss), and furnished with stomata ; 



IV. Growth terminal (at the apex only) with cellular and 

 woody tissue, true roots and simple stems, or stems with 

 simple branches (Club-Mosses, etc.). 



FiQ. 42. — Horizontal sec- 

 tion of stem of Cijathea ar- 

 borea, Tree - Fern. Wood- 

 bundles (white) near the 

 circumference. 



4* 



