The Validity of certain Allied Specles of the Moss Campylopus clavatus R.Br.

By G. O. K. Sainsbury

[Read before the Hawkes Bay Philosophical Institute, 11th May, 1928; received by Editor, 14th May, 1298; issued separately, 23rd November, 1928.]

Mr. H. N. Dixon, in his able revision of the New Zealand Mosses, has tentatively treated Campylopus appressifolius Mitt. and C. insititius H. F. & W. as distinct from C. clavatus R. Br. (New Zealand Institute Bulletin No. 3, Part 3, page 84 et seq.). The last named is the earliest published species of the three, and all belong to the Trichophylli section of the genus, i.e., those species in which some of the leaves, and especially the comal ones, end in a hyaline hair-point. C. insititius does not appear in Hooker's Handbook, but C. appressifolius is published there from Mitten's manuscript and is described as characterized by its leaves appressed in the dry state and by its dark-coloured auricular cells. In the Journal of the Linnean Society (Botany, 40, page 441) Mr. Dixon records, however, that the type plant of C. clavatus in Schwaegrichen's Herbarium is marked by large distinct auricles, and he suggests that the practical absence of them in Schwaegrichen's accompanying sketches has led to this species being wrongly treated as one lacking distinct auricles. There is no doubt whatever that the alar cells of C. clavatus are quite as distinct as those of C. appressifolius, and the descriptions in the Handbook are, to this extent, misleading. The taller habit and appressed sterile shoots are therefore the only differences which, if constant, would entitle the latter moss to specific rank, unless two other distinguishing marks mentioned by Mr. Dixon, i.e., the nerve, wider in C. clavatus, and the hair-point, shorter in that species, are sufficient to separate them (Bulletin No. 3 supra, page 85). I have collected many specimens of both mosses in widely separated regions of the North Island, and have received material of them from correspondents and herbaria, and as the result of an examination of the plants I have reached the conclusion that the two species are not distinguishable, and that consequently C. appressifolius is not entitled to specific rank. Plants with appressed sterile shoots appear in gatherings consisting mainly of the typical clavate form of C. clavatus; the appressifolius character is often associated with quite a short habit of growth; and so far as the hair-point is concerned I have collected specimens of a pronounced appressifolius type which lack this character entirely. The width of the nerve too is very variable, sometimes ranging in a single gathering from two-fifths to over one-half the width of the leaf-base. I have lately had an opportunity of examining several specimens of Campylopus from Cheeseman's Herbarium, and the original labelling of the packets indicates the difficulties felt in assigning material to these two species. A note by Cheeseman records his opinion that species referred to C. clavatus appear to be near C. appressifolius, and that he would have considered

them to belong there but for Carl Mueller's opinion to the contrary. Another packet is noted as identified by Geheeb as C. appressifolius but considered by Mueller as belonging to the other species. The fact really is that in all these cases the plants with appressed sterile shoots would if picked out make a typical herbarium specimen of the one species, whilst the residue would make equally good specimens of the other, and there cannot I think be any doubt that C. appressifolius is not entitled to anything more than varietal rank at the most. This species is not mentioned by Brotherus in the Musci (Vol. 10, Engler and Prantl's Pflanzenfamilien, 2nd Edition), but I am unable to say whether or not the omission is accidental. So far as C. insititius is concerned the alleged differences are more important. Certain species of the genus are characterized as to the leaves by a supra-alar region of narrow thin-walled hyaline cells passing obliquely upwards and outwards to the margin. This is a striking feature of C. introflexus (Hedw.) Mitt, and is considered to be a distinguishing mark of C. insititius. The alar cells too of the latter species are said to be very indistinct. Mr. Dixon deals with these characters in the Journal of the Linnean Society (vide supra, page 440), and records that one of the two type specimens of C. clavatus in Brown's Herbarium possesses a distinct area of hyaline differentiation, whereas this character is conspicuously lacking in the other, the supra-basal cells of which are comparatively short and more or less incrassate. These two specimens are labelled as being collected one in New Holland and the other in Van Diemen's Land, and Mr. Dixon assigns the one to C. insititius and the other to C. clavatus. Although such a striking difference in areolation would apear to separate the plants quite definitely, I find in the large quantity of material examined that this hyaline differentiation is nearly always present, in a greater or less degree, in plants of C. clavatus, including also those of the appressifolius type. It is a very variable character, and when present is usually more clearly indicated in the young leaves of the upper part of the stem. In some plants there is no trace of it at all, and this is evidently the case with the type specimen of C. clavatus; in others it may be as strongly defined as in C. introflexus. As regards the indistinctness of the alar cells I think that this is correlated to some extent with the degree of hyaline differentiation, and there is no doubt that defined cells of this kind are often practically lacking in plants of the insititius type; but here again there is a range of variation disclosed pointing to the conclusion that C. insititius is only an extreme form of a polymorphic species. C. clavatus is a moss of very wide distribution throughout at any rate the North Island and is extremely common on the ground in open situations, especially on clay banks amongst manuka scrub and in road-cuttings. It ranges from sea level to subalpine heights, and it is therefore not surprising to find amongst its members a high degree of variability due perhaps to epharmonic adaptation. I have communicated the results of this investigation to Mr. Dixon and he has expressed the opinion that the conclusions arrived at are probably correct, but that it might be advisable to retain C. appressifolius as a variety.