464 EQUISETACE^. [part n. 



pollen, and others abortive sporules. In some 

 of the species, the thecse are produced in 

 bracteated spikes, which resemble the young 

 strobiles on a Spruce Fir. The seeds of the 

 common Club-moss {Lycopodium davatum) are 

 used at the theatres to imitate lightning. 



ORDER CCXIII.— MARSILEACEiE. 



These are aquatic herbs, the thecse or recep- 

 tacles of which are always found in the axils of 

 the leaves near the root. In the genus Isoetes 

 (Quill wort) these are of two kinds, like those of 

 the Club-mosses, the one containing powder, 

 and the other granules ; but in Pepper-grass or 

 Pill-wort (PiUularia), the receptacles are four- 

 celled, and each cell contains both powder and 

 granules. Marsilea, from which the order takes 

 its name, is a native of Italy and other parts of 

 the south of Europe, where it grows in the same 

 manner as Duckweed does with us. 



ORDER CCXIV.— EQUISETACE^.— THE HORSE-TAIL 

 TRIBE. 



The thecse of these well-known plants are 

 contained in terminal cone-like spikes or cat- 

 kins, from four to eight lying in each scale. 



