CRYPTOGAMS 



445 



Order 2. Marattiaceae. 



This order includes a number of stately tropical Ferns with thickened tuberous 

 stems and usually very large leaves provided with two stipules at the base. 

 The sporangia are situated in groups (sori) on the under surface of the leaves, 

 and are either free (Angiopteris), or united to form an oval capsule-like body, the 

 chambers of which are the sporangia. The prothallium in contrast to that of the 



FIG. 404. Ophioglossum mdgatum. A-C, Stages 



in the developmeut of the antheridium from Fin. 405. Ophioglossum vitlgatum. A-C, De- 

 velopment of archegonium ; D, mature opened 

 archegonium with two .spermatozoids (s) in 

 front of the opening ; h, neck-cells ; hk, neck- 

 canal-cells ; o, egg-cell ; 6, basal cell. (After 

 BRUCHMANN.) 



a superficial cell ; the upper cell in C gives 

 rise to the cover -cells, the lower to the 

 mother - cells of the spermatozoids. D, 

 Antheridium not yet opened ; d, cover-ci-lls. 

 A'. SpiTiiwto/oids. (After BRUCHMAJTN.) 



Ophioglossaceae is a green, heart-shaped thallus, resembling that of a Liverwort 

 and growing on the surface of the soil. It is sometimes dichotomously branched. 

 The sexual organs resemble those of the preceding order but are developed on the 

 lower surface of the prothallus. 



Sub-Class II. Leptosporanglatae. 



Order 1. Filices. 



The Filices, or Ferns, in the narrower sense of the word, comprise a large 

 number of genera with numerous species, being widely distributed in all parts of 

 the world. They attain their highest development in the tropics. The Tree- 

 Feriis (Cyathea, Alsophila, etc.), which include the largest representatives of 

 the order, occur in tropical countries, and characterise the special family of the 

 Cyatheaceae. The stem of a Tree-Fern (Fig. 406) is woody and unbranched ; it 

 bears at the apex a rosette of pinuately compound leaves or fronds, which are 

 produced in succession from the terminal bud, and leave, when dead, a. large 

 leaf scar on the trunk. The stem, resembling that of a Palm in habit, is 

 attached to the soil by means of numerous adventitious roots. The majority 

 of Ferns, however, are herbaceous, and possess a creeping rhizome, terminating 

 usually iu a rosette of pinnate or deeply divided leaves. Such a habit and 

 growth are illustrated by the common Fern Aspidium filix mas, the rhizome 

 of which is official (Fig. 407). When young, the leaves of this Fern are 

 coiled at the tips (Fig. 407, 1, a), a peculiarity common to the Ferns as a 



