516 THE ARTIFICIAL SYSTEM OF LINNAEUS. 



2. Polygamia BUPERFLUA, the same as the last, except that 



the rays, or marginal flowers of the head, are pistillate 

 only. 



3. Polygamia frustranea, those with the marginal flowers 



neutral (Fig. 324, 325), the others perfect. 



4. Polygamia necessaria, where the marginal flowers are 



pistillate and fertile, and the central, staminate and 

 sterile. 



5. Polygamia segregata, where each flower of the head 



has its own proper involucre. 



6. Monogamia, where solitary flowers (that is, not united 



into a head) have united anthers, as in Lohelia. 



1003. The 23d class, Polygamia, has three orders, founded on the 

 characters of the two preceding classes ; namely, 



1. Mon(ecia, where hoth separated and perfect flowers are 



founded in the same individual. 



2. Dicecia, where they occupy different individuals. 



3. Trkecia, where one individual bears the perfect, another 



the staminate, and a third the pistillate flowers. 



1004. The orders of the 24th class, Cryptogamia, are natural or- 

 ders, and therefore not definable by a single character. They are, 



1. Filices, the Ferns. 



2. Muse i, the Mosses. 



3. Alg^e, which, as left by Linnaeus, comprised the Hepatica;, 



Lichens, &c., a3 well as the Seaweeds. 



4. Fungi, Mushrooms, &c 



