76 Transactions. 



Art. X. — The Ferns and Fern Allies of Mangonui County, with some 



Notes on Abnormal Forms. 



By H. Cause. 



[Read before the Auckland Institute, 16th December, 1914.] 



In the New Zealand botanical area, which embraces, in addition to the 

 mainland, the outlying groups of the Kermadec Islands, the Chatham Islands, 

 and the islands lying to the south,* there are 138 species of ferns, contained 

 in thirty-one genera. In addition, there are twenty-seven varieties named. 

 But there are also a good many forms not included in these species and 

 varieties, in some cases, no doubt, intermediate forms, in others forms not 

 specially distinguished, some of which, in my opinion, are, from their con- 

 stancy, worthy of distinction. 



Of the 138 species, there are in the Mangonui County ninety, and of 

 the varieties acknowledged in Cheeseman's " Manual of the New Zealand 

 Flora " there are fourteen. 



The names used in this paper are those of the Manual, except in a few 

 cases where changes have been made in accordance with the rules established 

 by the Botanical Congress of Vienna. f 



Filices. 



Hymenophyllaceae. 



1. Hymenophyllum Linn. 



Twenty species in Manual, represented by eleven species in Mangonui 

 County. 



2. Trichomanes Smith. 



Seven species in Manual, represented by five species. 



In shaded gullies Hymenophyllum scdbrum A. Rich, grows luxuriously, 

 especially on trees leaning over the creek. Here, too, are found H. dila- 

 tatum, H. demissum, H. polyanthos, and others, though by no means con- 

 fined to this situation. 



My most recent discovery among these delicate ferns in this district 

 was H. Cheesemanii. For years I have searched for this tiny fern without 

 success, always looking for it " among moss on the upper branches of forest- 

 trees." When I did find it, however, it was on the stems of small trees, 

 hidden in a dense growth of moss, which Mr. Cheeseman informs me is a 

 very unusual position. I have even found it on the shady side of a kauri- 

 tree, and, last of all, I did find it on the upper branches of a fallen tree. 



H. ferrugineum Colla. occurs plentifully in damp gullies on the stems 

 of Dicksonia squarrosa, not infrequently mixed with Trichomanes venosum 

 R. Br. T. reniforme Forst., the " kidney fern," occurs plentifully on fallen 

 logs as a rule. 



The most interesting among these ferns in this district is T. strict-um 

 Menz. It is decidedly rare. Usually it occurs in damp forests, but near 

 Kaitaia, the only place where this fern has been noted in the county, it is 

 growing on deeply shaded clay banks of a creek, and also on the margins 



* " Manual of the New Zealand Flora," Cheeseman, preface, p. iv. 

 t 'Notes on Botanical Nomenclature," Cheeseman, Trans. N.Z. Inst., vol. 40, 

 p. 464, 1908. 



