300 CHARACTERS OF TRIBES AND GENERA. 



"Synopsis" of the above work, the number is reduced to 

 seventy. With a few exceptions they are stemless, gene- 

 rally cespitose, with smooth glossy fronds, a few only 

 being slightly pilose or furnished with glands. The 

 greater number have free venation, but anastomose vena- 

 tion characterises Woodwardia and its allies. 



170. BLECHNUM, Linn., in part (1754). 

 Hook. Sp. Fil. 



Vernation fasciculate, csespitose, often stoloniferous, or 

 solitary erect, sub-arborescent. Fronds simple, pinnatifid 

 or pinnate, from a few inches to 4 to 6 feet high ; pinna3 

 adherent or rarely articulated with the rachis. Veins 

 forked ; the sterile venules free, or their apices thickened 

 and forming a cartilaginous margin ; the veins of the 

 fertile pinnae combined near their base by a transverse, 

 continuous, sporangiferous receptacle, constituting a linear, 

 costal, or rarely extra-costal sorus. Indusium linear, plane. 



Type. Blechnum occidentale, Linn. 



lllust. Hook, and Bauer, Gen. Fil., t. 54 B. ; Moore Ind., 

 p. 11 B. ; J. Sm. Ferns, Brit, and For., fig. 100 ; Hook. 

 Syn. Fil., t. 4, fig. 34. 



OBS. In the " Species Filicum " forty species of Blech- 

 num are described, but in the "Synopsis Filicum" they 

 are reduced to eighteen. 



Great confusion exists in the synonymy of this genus 

 with that of Lomaria, the most obvious distinguishing cha- 

 racter being in the fertile fronds of the latter being con- 

 tracted, but I must admit that this distinction is not always 

 definite, it being difficult to determine to which genus 

 certain intermediate forms belong, and, to make the matter 

 worse, Presl characterises the species of Blechnum under 



