Art. XXIX.—On a New Zealand Isotachis new to Science.

Transactions and Proceedings of the Royal Society of New Zealand, Volume 34, 1901, Page 325

Art. XXIX.—On a New Zealand Isotachis new to Science. By Ernest S. Salmon. Communicated by Robert Brown. [Read before the Philosophical Institute of Canterbury, 6th November, 1901.] Plate XX. The following description of a New Zealand Isotachis by Mr. E. S. Salmon, of Charlton House, Kew, was taken from specimens which I sent to him for determination. His description (which I am able to confirm) was published in the Revue Bryologique for June, 1901, at page 75. He has sent me copies of his paper, with drawings, one of which, with specimens of the plant, has been placed in the Museum at Christchurch. Isotachis stephanii, sp. nov. Robusta, dense cæspitosa, flaccida, sordide badia; caule usque ad 8 cent. longo flexuoso supra in ramulos subjulaceos partito interdum simphci inferne sordide badio apice læte badio, fohis distichis dense imbricatis flaccidis tenuibus erectis vel erecto-patentibus amplexicaulibus subcomplicatis late oblongis 3–3.5 mm. longis 25–3mm. latis basi ventricosis margine integro vel obtuse dentato ad 1/7 bifidis sinu infra plus minus angustato segmentis late triangularibus plerumque minute apiculatis cellulis superioribus firmis quadratis et breviter rectangulis 30–50 μ, longis 12–20 μ latis parietibus plus minus incrassatis trigonis nullis, cellulis inferioribus elongato - rectangulis, amphigastriis foliis paulo minoribus 2.5–3 mm. longis 2 mm. latis parum concavis cæteris conformibus. Reliqua ignota.

I. grandi Carr. et Pears. affinis,- sed habitu robustiore, foliis et amphigastriis majoribus minus profunde bifidis distincta. Hab. Growing in water in large round tutts on the top of a hill at Orepuki, Foveaux Strait; on the summit of Mount Thompson, one of the spurs of Mount Anglem, Stewart Island, New Zealand (Robert Brown, in litt., January, 1901). The hepatic above described was sent to me by Mr. Robert Brown, of New Zealand. The specimens sent, although sterile, clearly belonged to Isotachis, a genus which, as Gottsche has remarked (see Carrington and Pearson, in Proc. Linn. Soc. N.S.W., sec. ser, ii., p. 1042, 1888), “is readily recognised by its evenly arranged leaves and stipules, which last so nearly resemble the leaves in size and form that the foliage might almost be called trifarious.” Not being able to identify the plant with any species of Isotachis in the Kew Herbarium, I sent a specimen to Herr Stephani, who kindly informed me that it was a new species. I am indebted to Herr Stephani for the following note on the affinity of the present plant: “It is very near I. grandis, Carr. et Pears., but that plant has asymmetric leaves, the postical part being more rounded than the antical. It is a particular feature of the New Zealand plant that the leaves and stipules are perfectly symmetric. I. grandis also has the leaves (not always, but often) 3-lobate.” There is a small specimen of I. grandis (“on wet rocks, Lawson, Blue Mountains, N.S.W.”) in the Kew Herb., and in this the largest leaves measure 2 mm. by 1.75 mm. (Carrington and Pearson give 1.75 mm. by 1.5 mm.); the stipules measure 1.5 mm. by 1 mm. I. stephanii, besides having much larger leaves and stipules, differs in the manner in which the apex of these is bipartite. This is seen most clearly in the case of the stipules—in I. grandis the stipule is concave at the base of the sinus, and the sinus is not narrowed towards the base; in I. stephanii the apex of the stipule is plane, and the shallow sinus is distinctly narrowed downwards. Explanation of Plate XX. Isotochis stephani, sp. nov. Fig. 1. Part of plant, about natural size (left-hand branch turned round to show the stipules). Fig. 2. Leaf (flattened); x 17. Fig. 3. Stipule; x 17. Fig. 4. Areolation of leaf towards apex; x 270. Fig. 5. Areolation of leaf towards base; x 270. Fig. 6. Transverse section of stem; x 170.

Isotachis grandis, Carr. et Pears. Fig. 7. Leaf (flattened); x 17. Fig. 8 Stipule; x 17. Additional notes on the habitats of this plant: It grows on the nearly flat portions of the summits of the hills already named, in the drainage, which flows very slowly, varies in width from 1 ft. to several feet, and is about 1 in. in depth, with a muddy bottom. It is a very beautiful plant, being lustrous and nearly black. Like a large number of New Zealand plants, it appears to be very local. It is not plentiful in the localities named, which up to the present are the only places where it has been found. Fruit not known.—R. B.