1380 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
The relationship of the Stereocaulaceae to the Cladoniaceae in the possession of a 
primary and a secondary thallus and in apothecial characters is obvious. Indeed, 
the two families are seldom separated, and if we consider the apothecial characters 
alone there is certainly no reason for a division, But if we look at the secondary 
thallus (podetia) of Stereocaulon and Pilophorus closely it will appear that there 
is doubt as to whether any of the alge found in the phyllocladia, or even those rarely 
found in the loose network of hyphae, are other than foreign. The absence of a cor- 
tex would render the capture of foreign algee by the outer hyphal layer and the phyl- 
locladia an easy matter, and perhaps we have here, after all, at best only what may 
be regarded as pseudopodetia. Also the phyllocladia are certainly totally different 
structures from the squamules of the podetia of the Cladonias, but this of itself would 
give us no more ground for making two families for Cladonia and Stereocaulon than 
we should have for separating Peltigera aphihosa from the Peltigeraceae on account of 
the cephalodia. Further studies of the podetia must decide whether or not Stereo- 
caulon and Pilophorus may properly be included with the Cladoniaceae. And, 
indeed, the relationships can scarcely be understood until we know more of the 
phylogeny of the genera involved. Also, the relative rank of the genera can hardly 
be decided at present. 
STEREOCAULON=# Hoffm. Deutsch. Fl. 2: 128. 1795. 
Puate 18. 
The thallus, as in Cladonia, consists of a primary and asecondary. The primary 
thallus, however, is wanting in the mature plant, so that in the descriptions it may be 
neglected. The secondary thallus is conspicuous and permanent, composed of the 
podetia. The podetia are fruticose structures, much branched, the whole podetium 
being variously twisted and irregular. The central portion of each branch of the 
podetium is composed wholly of hyphe extending for the most part longitudinally 
and forming a solid cylinder, immediately surrounding which is a tangled mass of 
hyphez, which may be regarded as a medulla. Surrounding this medullary tissue 
on all sides is a looser layer of hyphe inclosing the algal cells and extending outward 
in all directions as warty or isidioid outgrowths, the so-called phyllocladia. There 
is no cortex in any of the species. Several kinds of algal cells may be looked for even 
in the same species. All, however, except perhaps Cystococcus, which is the most 
constantly present, may be regarded as foreign. A discussion regarding other alge 
present may be found in Schneider’s Text-Book of Lichenology. 
The apothecia are usually small or of medium size. They are located on the ends 
of the branches, and are convex or globose, or sometimes quite flattened. The 
proper exciple commonly disappears. The hypothecium is pale. The hymenium 
is pale or brownish below and commonly brownish or brown above. The paraphyses 
are rarely branched. The spores are hyaline, fusiform to acicular, and 4 to several- 
celled. 
The members of the present genus seem to be closely related to the Cladonias, 
though apparently still more nearly related to Pilophorus. 
Three species have been reported from the State. On earth over rocks, frequently 
a very thin layer of humus on a flat rocky surface or in a crevice. 
Type species Stereocaulon corallina (Wulf.) Hoffm. op. cit. 129. 
EXPLANATION OF PLATE 18.—Fig. 1, part of a plant. Fig. 2, a, the apothecia; b, the phyllocladia. 
Fig. 3, a section of the apothecium and a portion of the thallus; a4, the hymenium; b, the hypothecium; 
c, the medullary layer. Fig. 4, alongitudinal radial section of a podetium; a, aphyllocladium; 5, the exter- 
nal loose network of hyphiw; c, the internal mechanical tissue of longitudinal hyphw. Fig. 5, paraphyses 
and (@) an ascus. Fig. 6, free single spores. Fig.7, algal cells. Fig. 1. natural size; fig. 2, enlarged about 10 
diameters; figs. 3, 4, enlarged 300 diameters; figs. 5-7, enlarged 650 diameters. From Schneider. 
«The original spelling is followed. 
