Flowerless-Plant Study 



685 



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3w 



The Christmas fern. 



The contracted tips of some of the fronds consist of 

 fruiting pinna. 



Photo by Verne Morton. 



this rootstock may have been creeping on an inch or so each season for 

 many years, always busy with the present and giving no heed to its dead 

 past. One of the chief differences between our ferns and the tree-ferns of 

 the tropics, which we often see in greenhouses, is that in the tree-fern the 

 rootstock rises in the air instead of creeping on, or below, the surface of the 

 ground. This upright rootstock of the tree-fern also bears fronds at its 

 tip, and its old fronds gradually die down, leaving it rough below its crown 

 of green plumes. 



The Christmas fern has its green stipe, or petiole, and its rachis, or mid- 

 rib, more or less covered with ragged, brownish scales, which give it an 

 unkempt appearance. Its pinnae, or leaflets, are individually very 

 pretty ; in color they are dark, shining green, lance-shaped, with a pointed 

 lobe or ear at the base projecting upward. The edges of the pinnas are 

 delicately toothed, each point armed with a little spine, and the veins are 

 fine, straight and free to the margin; the lower pinnas often have the 

 earlike lobe completely severed. 



In studying a fertile fern from above, we notice that about a dozen 

 pairs of the pinnae near the tip are narrowed and roughened and are 

 more distinctly toothed on the margins. Examining them underneath, 

 we find on each a double row of circular raised dots which are the fruit- 

 dots, or sori ; there is a row between the midrib and margin on each side, 

 and also a double row extending up into the point at the base. Early in 

 the season these spots look like pale blisters, later they turn pale brown, 

 each blister having a depression at its center; by the middle of June, 



