50 DESCRFPTIONS OF N.Z. FERNS. 



GENUS DICKSONIA. (Dik-so-ni-a.) 

 So called in compliment to a Scotch botanist named Dickson. This has the sori 

 at the point of a vein near the margin of the frond. Involucres placed beneath the 

 sorus, sub-globose, coriaceous or membranaceous, opening across the top, so as to 

 appear more or less distinctly two-valved. About half the plants of this genus are 

 arborescent, with large decompound coriaceous fronds, the others have creeping 

 rhizomes. Our Dicksonias all belong to the sub-genus " Balantium," in which the 

 involucre opens across, but the valves do not fall right back. The outer half of the 

 involucre is formed of the reflexed margin of the frond. 



DICKSONIA SQUARROSA. (Dik-so-ni-a Squar-ro-sa.) 



"SLENDER TREE-FERN." "ROUGH TREE-FERN." M.\ORI NAMES, " WEKI " 



AND " TUAKURA." 



PLATE X., No. 6 ; and PLATE XXV., No. P. 

 This is probably the commonest of our Dicksonias, as it is found all over the 

 Colony, at all events at fairly low levels and also at the Chatham Islands, but not 

 elsewhere. It usually occurs in groups or groves, and mostly on low ridges or other 

 fairly dry places, and is often found in pretty exposed situations. The caudex attains 

 a height of twenty to thirty feet, and is very slender, seldom thicker than a man's fore- 

 arm. It may at once be known by the numerous black bases of old stipites, about 

 nine inches long, which remain all over the caudex and stand nearly straight up against 

 it. The crown consists of only a few broadly-lanceolate fronds, seldom more than six 

 feet long, which arch over rather gracefully, probably through having the stipes rather 

 longer in proportion than that of most tree-ferns. When young the stipes, rachis and 

 costae are densely covered with long black or brown hairs, and a few of these almost 

 always remain permanently towards the base of the stipes. The rest of them, however, 

 drop off and leave behind them prickly tubercles, which make the whole under-surface 

 of the frond feel very rough, whence the specific name, which means "scaly." The 

 stipes, rachis, and costae are all very dark brown below, and rather lighter and velvety 

 above, but it may be noted that the velvety portion does not extend over the whole 

 width, but is confined to a depression between higher edges. The frond is widest 

 about the middle, and does not decrease in width downwards so much as that of many 

 ferns, but as the lower pinnae are much deflexed'the frond looks narrower below than 

 it would do if they stood straight out. In fact, in young plants the lower pinnae hardly 

 decrease in length at all. Both primary and secondary pinnae are very shortly stalked 

 and the former are narrow in proportion to their length, numerous, rather crowded 

 together, and often are lengthened out into a long point. The lower pinnules 

 are stalked and the rest sessile ; and they are deeply cut into lobes, each of which 

 contains one sorus, over which it bends to such an extent as to form half of the 



