EOYAL FERN 



155 



Ferns, but in the genus Lygodium there are species with 



twining fronds which grow to considerable length. 



Hooker says that the New Zealand climbing Fern, 



L. articulatum, has fronds which may grow to a length 



of nearly 100 feet. 

 MarattiacecB. — A family which evidently embraced 



abundant species in remote geological times, and was 



then probably dominant among the Ferns; now it is 



reduced to twenty - five species, 



which are found only in tropical 



and subtropical regions. 

 Osmundacece. — Only eleven known 



species ; one confined to South 



Africa, four mostly to Australasia, 



and the remaining six are found 



mainly in the temperate regions 



of the Northern Hemisphere. One 



species is found in Britain — the 



beautiful Royal Fern, Osmunda 



regalis (Fig. 50) —which, alas ! is so 



much sought after by collectors 



that it is becoming rarer every 

 year. Some of the fronds bear no sporangia, but those 

 that do are so covered with them as to appear like 

 spikes of flowers arranged in a panicle — hence the 

 common misnomer, " Flowering Fern." 



Ofhioglossacece. — Twelve species, two of which occur 

 in Britain — the Moonwort, Botrychium lunaria ; and the 

 Adder's Tongue, Ophioglossum vulgatum. The pro- 

 thallus is tuberous, with the sexual organs sunk in its 

 tissue; it is always subterranean, and consequently 

 has no chlorophyll; to make up for this loss, it is 



Fig. 50. — Frond op 

 Royal Fekn bbakisg 

 Sporangia. 



