Survey of Plant Kingdom 135 



sists of true root, stem, and leaves. The small, microphyllous leaves 

 (mi kro -fil' us) (Gr. mikros, small; phyllon, leaf) are usually spirally 

 arranged. The roots and stems are usually branched dichotomously 

 (di -kot' o mus ly) (Gr. dicha, in two; temnein, to cut). Spore-produc- 

 ing sporangia occur singly on the upper surface of specialized leaves 

 known as sporophylls (spor'ofil) (Gr. sporos, spore; phyllon, leaf). 

 Usually the sporophylls with their sporangia are grouped at the tips of 

 the stems to form cones or strobili (strob' il i) (Gr. strobilos, cone) . The 

 spore-bearing organs are often foot or club shaped. Club "mosses" are 

 principally perennial, creeping evergreens, which explains their common 

 name of "ground pines." 



Examples: Club "moss" (Lyco podium) (Fig. 47) and smaller club 

 "moss" (Selaginella) (Fig. 48). 



Jtrobilus {cone) 



___iL(2aF 



Stem 



Boots 



Sporanqium 



b 



/ 



Spores 



Fig. 47. — Club "moss" or "ground pine" {Lycopodium sp.) of the subphylum 

 Lycopsida, class Lycopodineae. A, Branches bearing reproductive strobili, each 

 with sporophylls; B, sporophyll enlarged, showing sporangium and spores. 



B. Subphylum Sphenopsida (sf en -op' si da) (Gr. sphen. wedge; 

 opsis, appearance). — The horsetails belong to the class Equisetineae 

 (ek wi se -tin' e e) (Gr. equus, horse; seta, tail or hair) . The sporophyte 

 has true roots, stems, and leaves; the small leaves are scalelike (sometimes 

 wedgelike) and in whorls at the nodes of the hollow, jointed stems (dis- 

 tinct nodes) ; stems are usually ribbed and impregnated with silica which 

 explains the common name of scouring rushes. A horizontal, branched, 

 underground stem, or rhizome (ri'zom) (Gr. rhizoma, root) in most 

 species, bears two types of aerial stems: (1) the sterile, green branched 



