This is included in Saccardo as part of Xylaria, but we feel is well
entitled to generic rank. It was proposed by Ehrenberg in 1820 for a
curious species collected in Brazil. The genus differs from Xylaria in
having the fruiting bodies on the ends of branches, which in one
species are dichotomous, or in the other two species sessile or
subsessile and borne on a slender rhachis. There are conflicting
accounts of the structure of these bodies. The original, by Ehrenberg,
represents them as hollow bodies, with the perithecia imbedded in the
walls. That also is as shown by Cooke and is the usual idea. Moeller, on
the contrary, represents each body as a perithecium, and our examination
confirms Moeller's view. If Moeller's account is true, as it seems to
be, it is a strong reason why Thamnomyces should not be classed with
Xylaria.
The usual Xylaria has a white, sterile, central portion known as the
stroma, bearing a carbonous crust. The perithecia are generally imbedded
in the outer portion of the stroma, the mouths opening through the
carbonous crust. The walls of the perithecia are carbonous, and
confluent with the crust. The genus Thamnomyces has a slender stem,
entirely carbonous. This seems to have been the main difference between
it and Xylaria in the old classification, but the character is
fallacious.
There are Species of Xylaria that have no white stroma. The stem is
slender and carbonous and bears the carbonous fruit bodies, superficial,
but sessile and globose. Fries proposed for these species, the generic
name Rhizomorpha, which Saccardo united with Thamnomyces as a section of
Xylaria. In my view it is an entirely different idea from Thamnomyces
and should form a section in itself in the genus Xylaria. There are
Several species like Xylaria scopiformis that intimately connect
Rhizomorpha with Xylaria.
We believe the genus Thamnomyces, in the true sense, embraces only three
species as follows:
[Illustration: #Fig. 850.#]
THAMNOMYCES CHAMISSONIS (Fig. 850).--Stem Carbonous, black, smooth,
repeatedly dichotomously branched, the ultimate branches bearing ovate,
acute fruiting bodies. Structure of these bodies shown by Moeller is
entirely carbonous, hollow, each forming a single, carbonous
perithecium. Spores shown by different authors as of different shapes
and sizes. In our specimens they are 9 × 20-28 mic., dark, and arctuate.
They closely resemble the ordinary Xylaria spore.
This was originally named from Brazil by Ehrenberg, who gave a good
illustration of it. It has therefore escaped all synonyms, excepting by
Cooke, who discovered it was a new species and called it Thamnomyces
dendroidea. Hennings also discovered it from Africa, first as a new
variety, then as a new species, Thamnomyces camerunensis, but of course
everything that came to Hennings must be "new" something. It grows on
rotten, hard wood, and does not seem frequent in our American tropics.
In Africa, however, I judge it is more abundant as numbers of African
collections are in the museum at Berlin. We have only received it once,
at nice specimen (Fig. 850) from R. H. Bunting, Gold Coast, Africa.
[Illustration: #Fig. 851.#]
THAMNOMYCES CHORDALIS (Fig. 851).--Stem long, slender, several
proceeding from a common base, entirely carbonous, black, smooth.
Fruiting bodies (or perithecia?) sessile along the stem, ovate, with
slender apices, black. Spores oblong, arctuate, dark.
This, I believe, is only known from tropical America, but is apparently
not rare as it is recorded a number of times, mostly from Brazil. Fries
named it from French Guiana in 1830 and gave a characteristic
description of it. A co-type with the fruit mostly gone is at Kew. Later
Montagne got it also from French Guiana and gave a good figure and
description under the name Thamnomyces rostratus. He thought it was
different from Fries' species on account of the spores not being
globose, but the "globose" spores of the original description is
doubtless an error. The plants are surely the same. As Montagne's figure
is characteristic, the plant when subsequently found has usually been
recorded under his name. We present in our figure both Montagne's and
Fries' type.
[Illustration: #Fig. 852.#]
THAMNOMYCES FUCIFORMIS (Fig. 852).--In general appearance, this is the
same as Thamnomyces chordalis, but a much larger plant. The fruit
bodies (perithecia?) are more slender and are short, stalked. Our
figure, which is about half the spike, will show exactly the difference
between the two species. The plant was named by Berkeley from specimens
collected in Brazil by Spruce, and to this day is only known from this
old collection. The name is from the habits, "those of a fucus rather
than a fungus," a far-fetched comparison, for my impression is there are
no fuci that are carbonous, or have much resemblance to this plant.