204 



CBYPTOGAMS 



growth called the protonema, which spreads over the soil 

 and resembles a filamentous Green Alga. Finally shoots 

 appear as buds on the protonema (Fig. 343). 



476. It will be noticed that in the Bryophytes (Liver- 

 worts and flosses) the fertilization of the egg cell does 

 not, as in most Algte, produce an oospore which separates 

 from the parent and develops into a new and distinct 

 })lant. The fertilized egg remains in position in tlie 

 archegonium and gives rise to the spore-producing organ, 

 or sporogonium. 



FERNS AND FERN ALLIES (PTERIDOPHYTES) 



477. jNIost of the Ferns and Fern allies of to-da}' are 

 comparatively small plants, frequently with a creeping 

 haliit ; some grow partlv or wholly submerged ; while 

 several small species are floating plants. All this is in 

 strong contrast witli conditions in former freoloffical times. 

 In the Coal period Tree Ferns (now confined to the 

 tropics) were widely distributed. 

 Certain relatii,'es of the modern 

 slender, creeping Club Mosses (Fig. 

 357) were trees from 60 to 80 feet 

 in height. Sinularly some Equise- 

 tumlike plants, now represented 

 mainl)^ l)y species from 1 to 4 or .5 

 feet tall (Fig. 3.58) were toleralily 

 stout trees 30 feet higli. Forests 

 largely composed of these Crypto- 

 gams formed the immense coal de- 

 posits of tliat period. 



478. Ferns are still numerous, and 

 in some places are predominant fea- 

 tures of tlie vegetation. In the 

 tropics they are especiall}- abundanr 

 and large (Fig. 34-1). In most com- 

 mon species llie sterji is a creeping 

 rhizome (Fig. 345), wliolly or partly buried, so that all 

 tJiat one sees is tlie foliage rising from tlie ground. Ferns 



3-14. A tropical Tree Fern 

 — Keunee. 



