Art. XLV.—On a Remarkable Variety of Asplenium umbrosum, J. Sm.
[Read before the Nelson Philosophical Society, 11th November 1890.]
About twelve years ago I received from the Rev. F. H. Spencer a specimen of an Asplenium collected in the Nelson District, which presented several points of difference from any other New Zealand fern; but, unfortunately, it was in an imperfect condition, and no positive conclusions could be drawn as to its identity: it was therefore laid on one side until better material could be procured, and was forgotten until I had the pleasure of receiving specimens of the same plant from Mr. McKerrow Campbell, when it was clearly seen to be an Asplenium belonging to the sub-genus Athyrium, and at first sight appeared to be distinct from any New Zealand species. A closer examination showed, however, that it was a remarkable variety of Asplenium umbrosum, J. Sm., a species occurring on calcareous soils in many parts of the colony, although on a cursory examination it appears to have but little in common with the type apart from its membranous texture. A well-developed specimen of the typical form exhibits spreading drooping fronds, from 3ft. to 5ft. in length, and sometimes 4ft. across at their greatest breadth, thrice-pinnate, with the ultimate pinnules distant, and from ⅓in. to ¾in. long, deeply lobed or toothed. In a more frequent form the fronds are ovate-lanceolate in outline, from 1ft. 6in. to 2ft. long and from 6in. to 9in. broad, twice-pinnate, with close-set deeply-lobed pinnules; the rhachis in both forms being somewhat robust. The chief points ofdifference in the present plant are the attenuated rhachis, the smaller size, the weak.
habit, the extremely delicate texture, and the more simple cutting; while the stipe and rachis are more or less clothed with narrow-linear scales, which are sometimes piliferous. The fronds vary in form from oblong to deltoid, the apical portion in all cases being rather long and narrow. They are from 1ft. 5in. long and from 4in. to 6in. broad, the stipe being about one-half the length of the entire frond; and are twice-pinnate at the base, the upper portion being usually pinnatifid; the pinnules are rounded at the tips, and minutely or coarsely serrate. The sori are short, broad, and slightly curved.
Before the sori arrive at maturity the pinnules are flat and open, the entire frond generally resembling that of the North American Asplenium thelypteroides, Michaux, except that its outline is oblong rather than lanceolate; but as the sori approach maturity the pinnules become contracted at the margin, and slightly convex above, when the frond assumes the appearance of a small form of Aspleninum filix-fæmina, Bernh., in this respect surpassing another indigenous fern, Hypolepis distans, Hook., which has hitherto been supposed to approach it most closely in general appearance. The extremely membranous texture is very remarkable; it is nearly as delicate as Cystopteris fragilis, Bernh.
Mr. McKerrow Campbell informed me that the fresh plant when bruised exhales an odour like that of tobacco. Certain states of Doodia media are said to emit a similar perfume, although I have not been able to perceive it. A state of Pteris scaberula, A. Rich., gives of a delicious odour as of lemons; while Polypodium scandens, Forster, was formerly used by the Maoris, when mixed with fat, to anoint their hair and bodies, on account of its fragrance.
I append a technical description of the plant under notice, and have to acknowledge my indebtedness to Mr. McKerrow Campbell for his kindness in forwarding specimens.
Asplenium umbrosum, J.Smith, var. tenuiflium.
Rhizome creeping, more slender than in the type. Fronds erect or sub-erect, 12in. to 16in. high, oblong oblong-acuminate or deltoid, twice-pinnate at the base, pinnatifid above; pinnules flat or convex, minutely or coarsely serrate. Rhachis extremely slender, filiform above, more or less clothed with scattered membranous scales.
Hab. South Island, Takaka Valley, Nelson. J. McKerrow Campbell.