LICHENS AND LICHEN. PARASITES

- 203 U.A.N.Z. ANTARCTIC RESEARCH EXPEDITION
ending in a brownish epithecial gel ; asci cylindric-clavate, 8-spored ; ascospores monostichous below,
distichous above, hyaline, short ellipsoidal, about 8 X 5p in the ascus [ll X 8 fide Notyka],
immature spores showing a curious bipolar staining with haematoxylin, so that they might be
mistaken for polar-bilocular spores, mature spores clearly unicellular with a clear central nucleus.
Spermogonia oblately sphaeroidal, 250p in diameter, llOp tall, immersed in the cortex, wall
thin, spermatiophores 25p tall, dichotomous; spcrmatia 7-10 X lp, straight or slightly curved,
fusiform.
In spite of the abundance of the material, this has proved to be a. very puzzling species qr
group of species, although the separatiou from the other species of Usnea is not difficult. If
we include the four additional names based on specimens from Patagonia southward to 55" 24' S.,
which clearly belong in this group (if they be not identical with forms found in Kerguelen), we
have a total of six names, only G. Nauqnanni sufficiently well described to refer plauts to the111
with any certainty, and even here many possible characters for separation are wanting. At the
time I studied the types in Stirton's herbarium at the Art Galleries of Glasgow, this species conld
not be found, nor did I find it at the British Museum, where a large number of Stirton's specimens
hadbeen6'borrowed" by the late A.L. Smith. At least a portion has since been found, -and a
photograph of an evidently sterile portion has been figured by Lamb (Jour. Liiin. Soc. Bot., 52,
pl. 6, 11 ; 1939). In his description, Stirton states " similis N. mdmanthae" which he elsewhere
characterizes "The central axis in N. msluxmthus is thick, and the medullary fibres rather compact.
I find the reactions of Neuropoym melmanthus (Ach.) from N.3.-viz., fibrillae medullares K
fl [avescentes] dein rubentes ; I- " In his herbarium, I found two specimens : New Zealand, near
Wellington, J. Buchanan, and Tasmania, Mt. Wellington, W. Scott-Campbell. Therefore it seems
probable that his concept of N. melaxanthus was based on material of N. ciliatus (Nyl.) Krmplhbr.,
and his description should be interpreted accordingly.
When we consider the usual characters for separating groups of species of Usnea, we encounter
difficulties. In general, the relative thickness and compactness of the medulla is a useful character.
In one plant sectioned, the medulla is loose and arachnoid in the inner half, the whole four-thirds
the thickness of the axis; in another plant in sections taken in a comparable site on the main axis,
the medulla is very compact, with a tendency for a fracture plane in the middle, and less than
half the diameter of the axis, although the medulla appears to be somewhat looser on some of the
secondary branches. On the slender branches and ramuli, the medulla is completely lacking, the
algal layer extendng to the chondroid axis. Foveation characterizes the whole section Poveataa
of Ezczcsnea and is quite characteristic of certain other species of Nezcropogm. In this species, the
very slender, young plants are smooth; as they become older, some become deeply foveate on
the larger branches, while other branches of equal size remain terete and smooth. Similarly
papillation seems a quite specific character in several of the other subdivisions of Usnea, but
here, one branch may be conspicuously papillate and another branch of the same plant be without
a trace of papillae. Similarly, there is considerable variation in the number and arrangement
of the ramuli or cilia on the stems. Most of the apotl~ecia are conspicuously papillate, and more
or less ciliate, both below and on the margins.
Similarly, reactions with potash and paraphenylene diamine have been extensively used by
Stirton, Vainio, Motyka, and Lamb. In general, our plants from Kerguelen are K-, but one is
clearly K yellow then red, and one is K yellow then ferruginous, yet these reactions are not correlated
with other characters. The crystals are not characteristic, corresponding to Lamb, J our.
Linn. Soc. Bot., 52, 202, fig. 3; 1939.
Superficially the apothecia appear terminal, but in sections of apothecia, the chondroid axis