Bruce Fink.

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gives rise to an archicarp ; b, the conidiophore ; d to g, the stalk of the archicarp ; g
to j, the ascogonial coil; h, probably the ascogonium proper; k to m, the trichogjTie;
m, the antheridial conidum; n, the conidiophore. x 400. From Dodge.

Fig. 8. The archicarp of Pcltigera canina. One of four cells of the ascogonium
is shown at A, and a cell of the vegetative hypha from which the archicarp arose is
shown at s. There is supposed to be no trichogyne. x 750. From Ffinfstfick.



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Ohio Biological Survey



Vol. II— Plate II




Bruce Fink.



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THE ASCOMYCETES OF OHIO.— II

The Collemaceae*

bruce fink and c. audrey richards
General Considerations

Hitherto comparatively few descriptions of lichens as fungi have been
undertaken. In many short diagnoses of lichens, mention of the algal
hosts has been omitted, and many lichens have been treated thus in-
advertently as fungi. But in more lengthy diagnoses or descriptions, the
common practice has been to consider the algal host as part of the lichen.
In order to dispose of typical lichens as fungi, no greater departure from
the ordinary methods is required than to omit from the descriptions all
reference to the algal host, the thing which is now often done through
inadvertency. However, in order to apply to a few families of lichens
the methods commonly employed in the taxonomic disposition of fungi, a
method must be followed which diverges considerably from that which
has been employed by Hchenists.

If it should be found impracticable to treat any group of ascomy-
cetous lichens as fungi, the whole plan of treatment of ascomycetes
proposed in the first paper of this series would be impossible of execution.
Consequently, we have considered, in this second contribution toward a
knowledge of the ascomycetes of Ohio, a family of lichens, the treatment
of which as fungi probably involves as wide a departure from the
method commonly employed by students of lichens as any group that
could be chosen. In order to demonstrate as early as possible in this
series of papers how slight are the changes required in order to treat the
large majority of lichens as fungi, the Lecideaceae, another family of
lichens, will receive consideration in the next paper of this series.

The study of the Collemaceae has been made classic through the
contributions of several botanists. De Bary studied this group and
ascertained that the chlorophyllous cells are algal (3). Schwendener
soon extended this view to include the chlorophyllous cells found in all



• Contributions from the Botanical Laboratory of Miami University — XII.

35



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36 Ohio Biological Survey

lichens (6). Stahl chose members of the same family for the first im-
portant work on sexual reproduction in lichens (7). Sturgis (8) and
Baur (4) have since confirmed Stahl's results. Miss Bachman (1 and 2)
has found in a member of the Collcmaceae an interesting condition with
respect to the morphology and the behavior of the sexual reproductive
tracts and has obtained in the same plant the only important cytological
results thus far secured in the study of the sexual organs of lichens. The
results obtained by these workers are known to many botanists, have been
considered in part in the first paper of this series, and need no further
discussion here.

In working out a new taxonomic method, there is a distinct ad-
vantage in considering a group of plants in which many botanists are
interested. However, our prime motive in selecting the Collcmaceae was,
as explained above, to attack first a family of lichens, the treatment of
which as fungi probably presents as many difficulties as any that could
be selected. The species of this family grow mainly within the algal
hosts instead of containing these hosts in a limited area within somatic
•tracts of the parasites as do the great majority of lichens; and the de-
scriptions of gross characters hitherto given as morphological features
of members of the Collcmaceae belong largely to the algal hosts rather
than to the lichens themselves. Finding a satisfactory way to obviate
this difficulty and devising a new method for the study of the minute
morphology of these lichens have required spending much time and energy
on details, some of which have proved to be of little if any taxonomic
value and have not been included in the results presented in this paper.
One year was given to working out a method, which, in the last two years,
has been further elaborated in the studies of the Collcmaceae of Ohio
presented herein.

In connection with many difficulties encountered, it is fortunate that
the tissues of members of the Collcmaceae appear more distinctly in
sections than do those of the majority of lichens. This condition has
made it comparatively easy to study most of the details with respect to
structure of cortices, medullae, sexual reproductive tracts, and apothecia.
In a few instances, we have resorted to imbedding and serial sectioning;
:but most of our results have been obtained by free-hand sectioning with
.the razor. Flemming's triple stain, Delafield's hsematoxylin, and safranin
»were used with good results; but we depended mainly on the solution
of iodine which is used commonly in the study of lichens. Other
reagents used were water, potassium hydrate, Schulze's macerating fluid,
and alcohol. For macerating, potassium hydrate was found more satis-



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The Collemaceae of Ohio 2>7

factory than Schulze's solution. The measurements of microscopic^
features were taken from specimens treated with water only.

Limiting the area studied to a region near at hand gave the ad-
vantage of being able to secure material in fresh condition easily. While*
our area conforms to the requirements of the Ohio Biological Survey,
the collecting has been confined to the southwestern portion of the state,
extending roughly about one-fourth of the distance from the southern
boundary to the northern and somewhat more than one-third of the way
from the western boundary to the eastern. The principal collecting-
grounds are about Oxford, Eaton, West Alexandria, Mason, Washington
Court House, Greenfield, Paint, Bainbridge, Peebles, and Cincinnati.
Collections made by others in various portions of the state have been-
studied through material loaned from the herbarium of the Ohio State
University and have given a fairly satisfactory knowledge of the dis-«
tribution of several of the species within the state as a whole.

Just what changes in limitations of species would result from the
employment of a new taxonomic method could not be known until we
had examined a considerable number of species of the family. While
our paper covers only the sixteen species of the Collemaceae known in
Ohio, we have made preliminary examinations of about as many more.
This means that we have covered approximately one-fourth of the
species known to occur in North America. Thus far our method has not
required any changes in species-limits. Each species studied has shown
a sufficient number of morphological characters to mark it as distinct,
or has been found to modify the size, form, color, or general appearance
of the algal host in a peculiar manner. In our descriptions, the power
of modifying the algal-host colony has been treated as a specific,
physiological character of each species of lichen. Since the algal host
rather than any portion of the lichen itself, except the apothecia, is con-
spicuously visible in the field, we have given first under each name of a
species a statement concerning the manner in which the lichen has
modified its host. This brings into prominence that which is seen plainly
on first observation, and at the same time avoids the error of describing
the algal host as a portion of the lichen. Following the statement re-
garding the transforming action of the lichen on the algal host, such
characters of the lichen itself as have seemed to have considerable
diagnostic value have been recorded.

We have tried to present a method workable for the species found
in the area treated in this paper and also like that which must be em-
ployed when our method is extended to include the Collemaceae of a



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38 Ohio Biological Survey

larger area, or finally to the family as a whole. It is evident that the
taxonomic value of the diagnostic characters used, both morphological
and physiological, may be better known after a large number of species
has been, studied carefully, but it is not probable that extension of the
method given herein will involve other than minor modifications.

In deciding on a method of treatment of the algal host, other
ascomycetous lichens which will require treatment similar to that which
is given to the Collemaceae in this paper were kept in mind. Other
nosticolous lichens may be treated in essentially the same manner as the
Collemaceae. Other types are illustrated by Ephebe, the thallus of which
is similar to that of the Collefnacecr, but is found penetrating throughout
the tissue of the branched, filamentous alga, Sirosiphon, and by
Coenogonium, which has a mycehal thallus that covers a portion of the
filaments of the algal host, Trentepohlia. From a purely technical point
of view, it would be better, in treating the Collemaceae and all other
lichens which require special methods for disposition of the modified
algal host, to treat the host in a paragraph following the description and
dealing with habitat and distribution. However, the practical advantage
of placing immediately under the name of the species that which is first
noticed in field or laboratory is so great that all who use our descriptions
will doubtless agree that we are justified in departing from a more exact
scientific procedure sufficiently to place the statement about the trans-
formation of the algal host before the description of the lichen, which,
excepting its apothecia, is known only through microscopic study.

The penetration of the thallus of members of the Collemaceae
throughout the algal-host colony as a distinct mycelial structure unat-
tached to the algal cells (Fig. 1) renders the somatic areas so plainly
visible that even the sexual reproductive areas, imbedded in the vegetative
structures, are much more readily visible in section than those of most
other lichens. In beginning our work, it was thought that these re-
productive structures, so plainly visible, might be available in this family
of lichens for diagnostic purposes. The archicarps (Fig. 18) and the
spermagonia (Fig. 25) were carefully described for each species of
Synechohlastus studied, and later those of a majority of the species of
our other genera were more or less carefully examined, even though the
work on Synechoblastus indicated that these organs do not differ enough
in the various species examined to make them of diagnostic value, except
in a few instances. Added to this is the difficulty, sometimes very great,
of finding specimens that bear the sex organs, and the areas of the thallus
in which these organs occur.



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The Collemaceae of Ohio 39

The sex organs grow, for most part, during two months in the spring
and for the same length of time in autumn. These organs may be found
in specimens not collected during these periods ; but the cells are likely
to be dead, and the parts of the archicarps collected out of season are
not likely to have quite their natural form. The spermagonia likewise
must be studied at the right time, since the spermatia decrease in num-
bers and finally disappear entirely after the prime condition is past, while
the basidia become considerably enlarged. The spermagonia usually ap-
pear as minute protuberances, which are commonly some shade of yellow
or brown. They occur most frequently on the lobes and near the
margins, or at least externally to the areas occupied by mature apothecia.
They may be seen easily with a hand lens, especially after the lichen and
the algal host are moistened; but they are not easily distinguished, in
gross morphology, from young apothecia, which have not yet ruptured
the mass of structures which lie above them. There is no way of de-
tecting the presence of archicarps through external appearance, but they
usually occur toward the margins from the position occupied by the
scattered apothecia. Sometimes, however, the archicarps are found
within the region of the thallus occupied by the apothecia, and they rarely
occur well toward the center of the thallus. The more central ones are
likely to be past prime and more or less distorted.

Owing to the uncertainty of finding the sex organs and their slight
or infrequent taxonomic value, we have, after working them out labor-
iously, decided not to burden the diagnosis with matter of so little value
in determining species. Instead, we have given the results from studies
of these organs toward the close of the paper where they may be acces-
sible to those who may wish to consult them. Though the sexual tracts
are not of sufficient diagnostic worth to warrant lengthening the diagnoses
considerably in order to include them, it is true that critical workers on
the Collemaceae must hereafter take these structures into account. Miss
Bachman's results (1 and 2) and our own findings from several regions
widely separated (Figs. 14 and 20) prove that forms so much alike with
respect to somatic characters and their method of modifying the algal-
host colonies may differ so much with respect to the sexual tracts that
they can scarcely belong to the same genera (Pis. Ill and IV). This
means that critical workers on the Collemaceae must know at least the
general nature of the reproductive tracts in every specimen in which they
can be found in order to be reasonably certain that forms so much alike
otherwise do not differ greatly with respect to the sex organs and their
behavior. Some of the minor differences in size and form of the sexual



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40 Ohio Biological Survey

tracts within the family may be seen by consulting our figures (Pis. Ill
and IV), and the measurements given in the descriptions of the sex
organs. Our work on these areas in Synechoblastus illustrates the
rather slight differences within the species studied from this genus. The
differences in size of ordinary spermatia and the internal male repro-
ductive cells found in certain of the Collemaceae may be seen by com-
paring Figs. 14, 20, 21, 22, and 23.

One of the writers of the present paper had Miss Bachman's material
for examination during the progress of her studies. It seemed certain
enough that she was working on Collema pulposum until the peculiarities
with respect to the morphology and the behavior of the sex organs were
discovered. It then became apparent that her plants could not be
Collema pulposum, if those previously studied by Stahl (7) and
Sturgis (8) are this species. Unfortunately, the reproductive areas can
be studied successfully from herbarium material so seldom that it is
doubtful whether microscopic study of the type of the genus Collema
and the type specimen of Collema pulposum would help to decide which
plants are like the types with respect to the sexual tracts. To attempt to
treat in this paper the material with internal sex organs found in Ohio
would be premature. One of the writers will continue with taxonomic
studies of the material already examined by us from Wisconsin, Iowa,
Minnesota, Ohio, Missouri, and New York, with any other that we may
discover, while the other author pursues further cytologic investigations.

The thalli of members of the Collemaceae are composed entirely of
hyphae. The hyphae are commonly long-celled and loosely interwoven in
such fashion as to form a mycelial structure, which usually composes
the larger portion of the somatic areas. In the hypothecia and the
exciples, the hyphae are closely interwoven. In these areas, the cells of
the hyphae may be long, or they may be approximately isodiametrical and
so closely placed as to exclude interhyphal spaces. In Leptogium and
Mallotium there is a distinct cortex, usually one layer of cells in thick-
ness (Fig. 1), composed of a layer of roughly isodiametric end-cells of
hyphae which extend from the dorsal to the ventral surface. Lindau (5)
has proposed the term plectenchyma for the densely interwoven
parenchymatoid hyphal tissues of fungi and has distinguished two kinds,
the paraplectenchyma with cells roughly isodiametrical and the proso-
plectenchyma with the cells more or less elongated and the ends narrowed.
The paraplectenchyma is found in the cortices in certain genera of the
Collemaceae and in the exciples and the hypothecia of certain species.
The prosoplectenchyma is rarely seen in the plants which we have studied.



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The Collemaceae of Ohio 41

and we have not attempted to differentiate. Loosely interwoven hyphae
with much elongated cells we have designated mycelial structure. The
mycelial structure is probably present in the medullse of all somatic
tracts within the group, though a plectenchymatoid appearance is some-
times seen in the medulla in instances in which the hyphae are so densely
interwoven and so interspersed with algal-host cells as to obscure the
structure. The hypothecia and the exciples may be composed of ordinary
long-celled, but closely interwoven hyphse (Fig. 9), or they may be
plectenchymatous (Fig. 10). The hyphae of the meduUae extend in various
directions (Fig. 1), and the number that lie perpendicular to the surfaces
of the thallus is usually largest about the apothecia and toward the
margins of the thalli. This distribution gives strength to the thalli.

Perhaps no part of our work presented greater difficulty than de-
termining whether certain hypothecia, exciples, and meduUae, or certain
portions of these structures, are plectenchymatous or whether they are
composed of closely interwoven hyphae which have elongated cells.
Transitional conditions occur, and one may easily mistake interwoven
hyphae with elongated cells for a plectenchyma when the hyphae are
closely packed. We found a plectenchymatoid appearance in the meduUae
of certain specimens of Leptogium tremclloides (Fig. 2) and Leptogium
chloromelum, and even in the same section, certain portions may show a
plainly mycelial structure while others, in which the hyphae are densely
packed, may appear like a plectenchyma. Careful maceration failed to
show a true plectenchyma in any instance in our specimens of these two
species. Other species are said by certain workers to be plectenchy-
matous throughout, but it may well be doubted whether this is true. We
examined Leptogium tcnuissimiim, which is figured in Engler and Prantl
as plectenchymatous throughout, but found a plainly but densely mycelial
structure toward the lower surface. Leptogium plectenchymum, de-
scribed in this paper, varies greatly with respect to position and amount
of plectenchyma, but we found no specimens which were wholly
plectenchymatous in the vegetative areas. Certain hypothecia and
exciples present greater difficulty than any of the medullae that we have
examined, and only the use of high powers, the oil-immersion lens, and
careful maceration will solve the problem in many instances. We do
not wish to leave the impression that such obstacles arise in the study
of all the species of the Collemaceae. On the other hand, the typical
plectenchyma (Fig. 3) and the typical mycelial structure (Fig. 1) are
readily recognizable.



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42 Ohio Biological Survey

The apothecia of all of the Colletnaceae studied possess a more
or less strongly developed exciple. Surrounding the exciple and often
extending above it is a thalloid margin, composed of elements of the
lichen thallus, with which algal-host filaments are intermingled. The
thalloid margin is sometimes absent or overgrown, when the exciple is
naked as in many other ascomycetes. In some of the species, one must
resort to the oil-immersion lens to demonstrate the exciple. This struc-
ture extends below into the hypothecium, which is much thicker as a
rule and is always easily demonstrable. It needs to be made clear that
the thalloid margin is not a part of the apothecium, but belongs rather
to the somatic tract of the lichen, and is intermingled with elements of
the algal-host colony, which, in this family, obscure the real thalloid
margin.

The Collemaceae form a very distinct group of ascomycetes, especially
peculiar with respect to conditions of parasitism and resulting thallus
disposition and structure. In the lower members of the family, the
thallus is a mycelium pure and simple as found in Synechoblastus and
Collema. In certain other genera as Leptogium and Mallotium, the
mycelial structure gives way in part to a cortical plectenchyma. In rare
instances, the plectenchyma extends throughout a large portion of the
thallus, which, as noted above, is said by some students to be wholly
plectenchymatous in some species. A plectenchyma sometimes occurs in
the hypothecium and in the exciple, even in the lower members of the
family, in which the vegetative areas are wholly mycelial. Hence, it
seems safe to assume that the most primitive plectenchyma is that found
in the fruit rather than that found in the somatic areas. About and
below the apothecia of Leptogia, the plectenchyma is usually several
layers of cells in thickness (Fig. 3), and it is similarly thickened below
the apothecia in the material of Mallotmm at hand for examination.

An interesting series of transitional conditions which indicates how
a cortical plectenchyma may have arisen came to light in our studies of
Synechoblastus Haccidus (Figs. 6, 7, and 8). Short cells at the upper
and the lower ends of erect hyphae often coalesce over limited areas of
the thallus and form either a typical plectenchyma, or a structure strongly
suggestive of a cortical plectenchyma. In some instances, the cells which
coalesce are elongated and form a palisade which differs considerably
from a true plectenchyma (Fig. 6). Over other areas the short end-
cells are formed but do not cohere (Fig. 7). On account of these
transitional conditions, this species is often placed in the genus Leptogium
in herbaria. In Leptogium chloromelum, the plectenchymatous cortex is



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The Collemaceae of Ohio 43

often poorly developed, and in some instances it is discontinuous and
recalls the conditions just noted for Synechoblastus flaccidus. These
two species bridge fairly well the gap between members of the
CoUetnaceae which have no cortex and those which have one. Some of
the material of Mallotium also showed a poorly developed and scarcely
continuous cortical plectenchyma.

Sweeping statements to the effect that paraphyses are uniformly
simple in many families of ascomycetes are due to the careless manner
in which the examinations are made. We have not studied a species of
the Collemaceae in which branched paraphyses do not occur (Fig. 11).
In instances in which it is difficult to ascertain the structure, maceration
and examination with an oil-immersion lens will always reveal branched
paraphyses, often in large numbers. Though simple paraphyses occur
in all of the species that we have studied, branched ones sometimes appear
to be more numerous than the simple ones when one makes a careful
examination.

The spores of the Collemaceae are hyaline and vary from simple
ones to muriform conditions (Fig. 13). The occurrence of muriform
spores in Collema and simple ones in genera that have a plectenchymatous
cortex makes it probable that there are at least two lines of descent within
the family, one expressed mainly in the spore evolution, and the other
showing the spore evolution and also the development of a cortical
plectenchyma. In separating Synechoblastus, with several-celled spores,
from Collema, which has muriform spores, we are following the tendency
among students of ascomycetes to give more prominence than formerly
to spore characters, in limiting genera. A gradual evolution from simple
spores to several-celled ones and from these to muriform types is well
known in many groups of ascomycetes; and transitional conditions in
which a species may have either simple or septate spores, or either
several-celled or obscurely muriform ones are occasionally met. There-
fore, one sometimes meets difficulties in using spore characters as
taxonomic criteria in the Collemaceae and in some other ascomycetes.
However, we have encountered no difficulty in the species treated in this


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