FILICINEM. • 409 



CLASS VIII. 

 FILICINE^. 



The plants included in the group of the Filicineae are distinguished from the 



Squisetacese and from the Dichotomeae by the various and complete development 



^hich their leaves attain. In proportion to the stem, the leaves are always of con- 



Iderable size, and in their anatomical structure, as well as in their external form, 



ley manifest a higher differentiation than do those of the two groups above 



lentioned. In these two groups the whole external form of the plant depends upon 



le formation and branching of the stem, and the most important physiological 



mctions are performed by this organ; in the Filicineae the stem is essentially an 



jrgan for bearing leaves and roots ; its growth is slow, frequently its development is 



imperfect that no internodes are formed, whereas the leaves are endowed with an 



:tive apical growth which continues for a considerable time and in some cases is 



mlimited. Further, the stem, in the Filicineae, has but little tendency to branch ; in 



?hole families it remains simple, and not unfrequently the formation of buds is 



Provided for by the leaves in which a strong tendency to branch is manifested, and 



"which present, in consequence, the most varied forms of pinnate and palmate 



segmentation and of dichotomous branching. In the Equisetacese and Dichotomese 



it generally happens that the stem takes part in the formation of the fructification ; 



in the Equisetaceae it is always and in the Dichotomeae it is usually an apical 



spike which is terminal upon the branch bearing it. In the Filicineae this is never 



the case ; the function of reproduction is discharged solely by the leaves, the stem 



taking no part whatever in it. The leaves bear very numerous sporangia (the 



number varying with the size of the leaf), whereas the peltate scales of the Equise- 



taceae bear but a few, and the fertile leaves of the Dichotomeae only one. The mode 



of development of the sporangia upon the leaves of the Filicineae is not uniform ; 



in the Stipulatae each sporangium arises from a group of epidermal cells, in the 



Filices and Rhizocarpeae from a single epidermal cell \ 



It appears, moreover, that the Rhizocarpeae, which were formerly separated 

 from the Ferns on account of the mode in which their fructification is developed, 

 present (more especially the Salviniaceae) a sufficient number of resemblances to the 

 true Ferns to justify us in regarding them as a branch of the ancestral tree from 

 which the Hymenophyllaceae and Polypodiaceae have sprung. 



It is not easy to give a brief account of the relationships existing between the 

 groups contained within this class, for a whole series of Ferns, the Osmundaceae, 

 Schizaeaceae, and Gleicheniaceae have been as yet but imperfectly investigated from a 

 morphological stand-point. Our present knowledge (1874) of these plants is very 

 superficial, it suffices merely for the diagnoses of systematists. For those who 

 can obtain the necessary material and who possess the requisite morphological 



' [See Goebel, loc. citJ] 



