696 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM. 



PHYLUM 3. ARCHEGONIATJJ. 



Plants showing a well-marked alternation of generations, that is of a sexual 

 (oophyte) and an asexual generation (sporophyte). The latter reproduces the 

 former by means of spores, the former the latter by means of egg-cells contained in 

 archegonia. Fertilization is by means of spermatozoids which swim in water. 



Class I. BRYOPHYTA. 



The sexual generation is in the greater number of cases a leafy shoot, arising 

 from a branched, filamentous protonema. The asexual generation, which arises 

 from the archegonium, is a stalked or sessile capsule containing' spores; it is 

 destitute of leaves, and never becomes independent of the oophyte. 



Alliance XX. Hepaticae, Liverworts. 



Oophyte nearly always dorsi- ventral; either thalloid or leafy. Protonema incon- 

 spicuous. Sporophyte a stalked or sessile capsule containing spores and usually 

 elaters. A calyptra is not present. 



Families: Ricciacece, Marchantiacece, Anthocerotacece, Jungermanniacece 

 The oophyte generation in the first three families is a branched, ribbon-like or 

 lobed thallus (cf. fig. 196 \ p. 23), showing a distinction between its upper and lower 

 surfaces, i.e. is dorsi-ventral. In the Jungermanniace* it is likewise thalloid in some 

 forms, but in the great majority the oophyte has the form of a leafy shoot. The 

 oophyte communicates with the substratum by means of rhizoids. The complete 

 oophyte is preceded by an inconspicuous filamentous growth, the protonema which 

 directly from the spore, but this stage is not so well marked as in the Mosses 

 sexual organs are borne usually in groups either in little depressions or upon 

 special outgrowths of the thallus, or, in the leafy forms, are collected together into 

 little 'flowers" at the tips of the shoots or in the axils of the leaves. The female 

 organs or archegonia are flask-shaped bodies with long necks, as in mosses The 

 egg-cell is contained in the enlarged basal portion, and on fertilization develops into 

 . sporophyte or spore-capsule. The antheridia are delicate, stalked, oval or club- 

 ped bodies in which the 2-ciliate spermatozoids are developed. They resemble 

 Chara shown in fig. 374' (p. 660). The spore-capsule develops within the 

 hegonimn; lts lower portion (in all but the simplest cases) forming a "foot or 



ortL^h ^f" imbedded " ^ SUbStanCe f the "P^ its W- Potion 

 sTa k'is d T I r^" ^ ^^ ' rm8 ' ******* - the Jungermanniace,, 



and ca 



, ' s 



nor " ^ * 



happens in M ^^ raised p as a cap on the capsule as 



^ " "^ ^^ OpenS ^ ^^ **> valv'es. In 



r sen n with the spores - They are io ^ thr - d - iike * 



of the wall, and as they dry become very hygroscopic and 



