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I UNITED STATES DEPARTMENT IDF THE INTERIOR 

Harold L. Ickes, Sectl tary 

GEOLOGICAL SURV :Y 

W. C. Mendenhall, Direc r 

Professional Paper 185-H 

THE FLORA OF THE NEr ALBANY SHALE 

PART 1. DIICH1VIA KENTUCKIENSIS, A NEW REPRESENTATIVE 

OF THE CALA·MOP1 

TYEAE 

BY 

CHARLES B. RE D 

Shorter contributions to general geology, 1934-35 

(Pages 149-161) 

UNITED STATES 

GOVERNMENT PRINTING OFFICE 

WASHINGTON : 1936 

For sale by the Suporintendent of Documents, Washington, DC. - - - - - - P{ice 5 ccntJi 
CONTENTS 

Page 

Abstract---------------------------------------------------------------------------------------------------- 149 

Introduction_______________________________________ ______________ ____________________ ___ _____________________ 149 

Occurrence and preservation------------------------- ~----------------------------------- ---------------------- 149 

Present status of the Calamopityeae __________________________________________________ -- _ _ _ _ _ _ _ ___ _ _ _ _ _ _ _ __ _ _ _ _ _ 150 

Systematic descriptions_______________________ ______ __________________________________________________________ 151 

Relationships of Diichnia____ _ _ __ _ _ _ _ __ _ _ _ _ _ __ _ _ __ _ _ _ _ _ _ _ __ _ _ _ _ _ _ _ _ _ _ __ _ _ __ _ _ _ _ _ _ _ _ _ _ __ __ __ __ _ _ _ _ _ _ _ ___ __ _ _ _ _ __ 154 

Conclusions __________________________________________________________ ~_-·· ____________________________ -------- 155 

ILLUSTRATIONS 

Page 

PLATES 3Q-33. Diichnia kentuckiensis Read ____________________________________________________ ----- __ ------ __ 157-161 

FIGURE 9. Camera Iucida sketch of a transverse section of Diichnia kentuckiensis____________________________________ 151 

FIGURE 10. Camera lucida sketches showing the origin and course of the leaf strands in Diichnia kentuckiensis__________ 152 

II 
THE FLORA OF THE NE ALBANY SHALE 

PART 1. DIICHNIA KENTUCKIENSIS, A NEW RE RESENTATIVE OF THE CALAMOPITYEAE 

By CHARLES B. READ 

ABSTRACT 

i A new genus of the Cycadofilicales, Diichnia, is described 

from the New Albany shale, of late Devonian age, in central 

Kentucky. The one known species, which is based on stem 

material showing internal structure, belongs in the family 

Calamopityeae. Foundation for the generic segregation is seen 

in the double leaf trs.ce of the genotype, D. kentuckiensts, in contrast with the originally single trace in other known representa -

tives of the family. 

INTRODUCTION 

.The flora of the New Albany shale, of late Devonian 

age, in central Kentucky is of particular interest. 

First, very little is known of the older vascular plants in 

North America, and this flora presents a comparatively 

large assemblage of forms, several of which belong to 

genera new or meagerly known. Second, the material 

·offers unusual opportunity to study the details of morphology of the stems and rachides, for in many specimens the internal structure is well preserved. As the 

methods of investigation of this flora are particularly 

time-consuming, however, and as the writer's duties are 

such that he cannot devote his undivided attention to 

this one project, it has been considered desirable to 

publish the discussion of the flora in a series of papers, 

of which this is the first. The others are to follow as 

opportunity offers. 

The specimens on which this paper is based came 

from one locality but from several collections. Several 

years ago David White, while engaged in geologic 

w·ork in the vicinity of Junction City, Ky., obtained 

a small fragment of a stem fron1 the top of the New 

Albany shale. In 1930 this was placed in the 

writer's hands. Preliminary inspection suggested that 

the stem is a "Calamopitys," but after sections were 

cut it became evident that though the plant is plainly 

related to Calamopitys it is new and presents several 

features of great interest. InN ovember 1932 the writer, 

on the advice of Charles Butts, visited the Junction City 

locality and spent several days collecting plant remains. 

Amid a wealth of valuable material additional ~pecimens of the calamopityean form here described were 

obtained, so that it became possible to clear up points 

only vaguely shown in the original specimen. 

The writer wishes to express his warmest thanks to 

David White, of the United States Geological Survey, 

who throughout the course of this work has given freely 

of useful advice and constructive criticism. He is 

likewise indebted to J. B. Reeside-, Jr., and R. W. 

9414-36 

Br wn, of the Geological Survey, for suggestions on 

certain features of the work. K. J. Murata has prepared the series of thin sections used, and his careful 

work is deeply appreciated. 

OCCURRENCE AND PRESERVATION 

The material here described came from a locality in 

the Harrodsburg quadrangle half a mile west of 

Junction City, Ky. Here a small outlier of green 

New Providence shale rests on black shale which is 

of New Albany age. Very excellent exposures are displayed at the heads of several small streams. At the 

most extensive of these exposures, the locality known 

as "Blue Licks", the following section was measured: 

Section of New Providence and New Albany shales at Blue Licks, 

half a mile west of Junction City, Ky. 

Ft. in. 

Green clay shale weathering gray-blue; contains 

scattered concretions of clay-ironstone_____________ 64 

Ferruginous sandy shale containing abundant Taonurus ______ ______________________________ _ 

Green clay shale weathering gray-blue_______________ 11 

Fine-grained ferruginous and slightly calcareous sandstone, the exposed surfaces showing abundant 

fucoidal markings ___ _______________ . _ _ _ _ _ __ _ _ __ 1 6 

Green clay shale, nearly structureless and weathering 

light blue; ferruginous concretions numerous and 

restricted to definite layers______________________ 14 

Green New Albany shale containing kidney-shaped phosphatic nodules that bear plant remains, fish scales, 

bone fragments, and in vertebrates________________ 1 2 

Black New Albany shale. Biack thin-bedded bituminous shale containing Sporangites. 

The plant remains occur in the nodular layer, either 

as the nuclei of concretions or as impregnated masses 

lying directly in the clay-shale matrix. This nodular 

layer is referable to the top of the New Albany, rather 

than to the New Providence. Published reports have 

in the past indicated this layer as the basal member of 

the New Providence, however. 1 This is due to the 

similarity of the clay matrix carrying the nodules and 

the overlying clays of undisputed New Providence age. 

A full discussion of the stratigraphic problems is deferred until a later paper. It is from this bed that 

the collection described by Scott and Jeffrey la 

1 Butts, Charles, The Mississippian series of eastern Kentucky: Kentucky Geoi. 

Survey, ser. 6, vol. 7, correlation chart, 1922. 

Ia Scott, D. H., and Jeffre-y, E. C., On fossil plants, showing structure, from the 

base of the Waverley shale of Kentucky: Roy. Soc. London Philos. Trans., ser. B, 

vol. 205, pp. 315-373, pis. 27-39;1914. 

149 
150 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY 1934-35 

in 1914 was obtained. Their material included the 

following species: 

Calamopitys americana Scott and· Jeffrey. 

Calamopteris hippocrepis Scott and Jeffrey. 

Periastron perforatum Scott and Jeffrey. 

Stereopteris annularis Scott and Jeffrey. 

Archaeopitys eastmanii Scott and Jeffrey. 

Lepidostrobus fisheri Scott and Jeffrey. 

The type of preservation of this material is very 

interesting. Analyses indicate that the petrifactions 

contain about 26 percent of calcium phosphate and 42 

percent of ferric carbonate. Although these materials 

preserve the larger structures of the plants with considerable accuracy, the details of pitting are commonly 

obliterated, owing to a peculiar swelling of the cell 

walls. · 

PRESENT STATUS OF THE CALAMOPITYEAE 

The known representatives of the Calamopityeae 

have been carefully studied and reviewed in recent 

years by several paleobotanists, including Scott and 

Jeffrey/a Zalessky,2 and Scott,3 and some new types 

indicating a considerable diversity in structure in the 

group have been brought to light. It is not necessary, 

therefore, to dwell at any great length on the historical 

aspects of the investigation of the group, though it is 

essential to review rapidly the major morphologic 

features of several of the species that are more or less 

allied to the form described here as new. 

Prior to 1901 the known species of Calamopitys 

were those originally described from Saalfeld, 

Thuringia, by Unger 4 and more completely elaborated 

by Solms-Laubach.5 The first of these, Calamopitys 

saturni Unger, is the type of the genus, although still 

imperfectly known. The most significant features of 

this species are the narrow zone of secondary wood with 

numerous broad rays, the distinct, centrally mesarch 

xylem strands, the large pith, and the primitively 

monarch leaf traces dividing after their departure from 

the stele into several small bundles to form the 

Kalymma petiole. 

From the same deposits Solms-Laubach recognized 

a second species, Calamopitys annularis, referred to 

Stigmaria by Unger. 6 This form is similar in most 

respects to Calamopitys saturni but differs in having a 

nearly continuous zone of eccentrically mesarch 

primary xylem, in the presence of medullary tracheids, 

and in minor features of the leaf trace. 

Ia See footnote 1a, p. 149. 

2 Zalessky, M. D., Etude sur l'anatomie du Dadoxylon tchihatcheffi Goeppert: 

Com. g~ol. [St.-P~tersbourg] M~m., pt. 58, 1911. 

3 Scott, D. H., Notes on Calamopitys Unger: Linnean Soc. London Jour., Botany, 

vol. 44, no. 297, pp. 205--232, pis. 6-8, 1918; Fossil plants of the Calamopitys type 

from the Carboniferous rocks of Scotland: Roy. Soc. Edinburgh Trans., vol. 43, 

pt. 3, pp. 569-598, pis. 1-6, 1924. 

' Unger, Franz, in Richter, Reinhard, and Unger, Franz, Beitrag zur Palaontologie 

des Thiiringer Waldes, Theil2, Schiefer- und Sandsteinfiora: K. Akad. Wiss. Wien 

Denkschr., Band 11, p. 81 [167], 1856. 5 Solms-Laub!c>ch, H ., Ueber die Seinerzeit von Unger beschriebenen strukturbietenden Pfianzenreste des Unterculm von Saalfeld in Thiiringen: K. preuss. 

geol. Landesanstalt Abh., neue Folge, Heft 23, 1896. 

o Unger, Franz, op. cit., p. 81 [167], 1856. 

In 1902 Scott described two species, Calamopitys 

fascicularis and C. beinertianus (Goeppert), which are 

quite distinct from those recorded from Saalfeld. 

Both species show a secondary wood of the typical 

cordaitean type with narrow medullary rays. C. 

jascicularis has a small pith surrounded by a ring of 

distinct mesarch xylem bundles which pass into the 

leaf traces after division. The leaf traces indicate a 

two-fifths pbyllotaxy and are monarch. C. beinertianus has a somewhat larger sclerotic pith enclosed by 

partly confluent primary bundles that show a strong 

tendency toward endarchy, particularly in the smaller 

ones. The leaf trace departs as a single mesarch 

xylem strand. 

In 1911 Zalessky 7 erected a new genus, Eristophyton, f 

for these two species and suggested that the similarities 

seen between Eristophyton fasciculare and E. beinertianum, on the one hand, and Calamopitys of the 

original group of C. saturni Unger, on the other, might 

be analogies and that the species are far removed in 

their affinities. Though it has been shown that this 

similarity between Eristophyton and Calamopitys in the 

strict sense is actual, Zalessky's segregation is regarded 

as a valid one, although Eristophyton is placed by some 

authorities as a subgenus and by others as a genus. 

The latter course is preferred by the present writer. / 

· The group of Calamopitys conforming to the strict 

definition based on C. saturni Unger has been segregated by Scott 8 in the subgenus Eu-Calamopitys. 

In addition to the Thuringian species there are nowl 

known C. americana .Scott and Jeffrey and C. radiata 

Scott, the first from the top of the New Albany 

shale in Kentucky and the second from the Oil Shale 

group, Calciferous Sandstone series, Dumbarto;r;tshire,J 

Scotland. . 

Calamopitys americana, it has been remarked by 

Scott,9 is scarcely distinguishable from C. annularis 

(Unger) Solms-Laubach on the basis of p.resent 

information. In view of their occurrence at widely 

separated localities they have, however, been regarded 

as probably distinct. 

Calamopitys ridiata Scott is rather distinct from any 

of the species so far mentioned. In the apparently 

mixed pith, the large exarch primary xylem strands, 

and the greatly dilated rays there are features which 

are undeniably of specific worth. No leaf traces have 

been observed. 

In addition to these segregates in the original genus, 

two new genera that appear to be closely related to 

Calamopitys have been recently defined.10 The first 

of these, Endoxylon Scott, is diagnosed as follows: 11 

7 Zalessky, M. D., Etude sur l'anatomie du Dadoxylon tchihatclieffi Goeppert. 

Com. g~ol. [St -P~tersbourg] Mem., pt. 58, p. 27, 1911. 

s Scott, D. H., Studies in fossil botany, pt. 2, pp. 108-109, 1923. 

9 Scott, D. H ., Notes on Calamopitys Unger: Linnean Soc. London Jour., Botany, 

vol. 44, no. 297, pp. 205-232, pis. 6-8, 1918. 

to Scott, D. H., Fossil plants of the Calamopitys type from the Carboniferous rocks 

of Scotland: Roy. Soc. Edinburgh Trans., vol. 43, pt. 3, pp. 569-596, pis. 1-6, 1924. 

u Idem, p. 579. 1 
FLORA OF THE NEW ALBANY SHALE, PART 1 151 

Pith large, without medullary tracheids or sclerotic nests. 

Primary xylem strands large, far apart, endarch. Secondary 

wood dense, with narrow medullary rays, usually uniseriate 

and mostly only 1 cell in height; others up to about 6 cells high. 

Pits in 1 to 4 rows on the radial walls of the tracheids. Annual 

rings distinct, marked by the very narrow tracheids of the 

"autumn wood." 

Insofar as present information goes the genus is 

monotypic, Endoxylon zonatum Scott being the only 

species. The type specimen came from the Carboniferous Limestone series of Ayrshire, Scotland. 

The second genus is Bilignea (Kidston ms.) ScottP 

Its diagnosis is as follows: 

Pith replaced by a large central column of short, pitted 

tracheids. Leaf trace a single or bilobed strand in passing 

through the wood; mesarch in the upper part of its course, 

dwindling in size and losing its centripetal xylem as it passes 

down the stem. Secondary wood dense; medullary rays narrow 

and almost always uniseriate, from 1 to about 20 cells in height. 

Bordered pits of the araucarian type, in 1 to 4 rows on the radial 

walls of the tracheids. 

Two species of Bilignea have been recognized, B. 

solida (Kidstone ms.) Scott and B. resinosa Scott,t3 

the principal feature of distinction being the presence 1 

of secretory sacs in the central column of the latter 

and their absence in the former. Both come from 

Scotland, B. solida being derived from the Carboniferous of Ayrshire and B. resinosa from the Cementstone group, Calciferous Sandstone series, Dumbartonshire. 

SYSTEMATIC DESCRIPTIONS 

CYCADOFILICALES 

CALAMOPITYEAE 

Genus DIICHNIA Read, n. gen.'4 

Stems of various sizes containing a "mixed" pith· 

Pith distinctly angled, at least in the genotype, I 

eccentrically mesarch xylem strands being situated at 

the angles and separated from the secondary wood 

by a few cells of parenchyma. Secondary wood very 

scant and traversed by wide rays; pitting not known. 

Cortex similar to that in Oalamopitys. Leaf trace 

double, two strands from adjacent angles of the pith 

passing outward and dividing to form a polydesn1ic 

petiole, the exact nature of which is not definitely 

known. 

Diichnia kentuckiensis Read, n. sp. 

General features of the stem.-The general features 

of the stem here designated Diichnia kentuckiensis, 

ri. sp., are clearly shown in figure 9, which is a diagram 

of a transverse section. The axis is of the less woody 

type characteristic of the subgenus of Oalamopitys 

designated Eu-Oalamopitys by Scott15 and in its woody 

structure is quite typical of the more "herbaceous" 

Cycadofilices. 

_12 Scott, D. H., op. cit., pp. 579, 590-592 .. 

13 Idem, pp. 579-592. 

u From the Greek lil, two, and txvos, footstep, trace, scar, etc. 

_15 Scott, D. H., Studies in fossil botany, pt. 2, p. 108, 1923. 

The central area is occupied by a large five-angled 

pith, the details of which are discussed beyond. 

Scattered in this pith are tracheids, so that the condition is of the type commonly designated "mixed." 

In the vicinity of each angle there are small areas of 

protoxylem; elsewhere such primary elements are 

usually absent. These protoxylem areas, as subsequently shown, are intimately connected with the 

leaf traces and vary somewhat in their position and 

configuration, which depend on their proxiinity to 

such emerging appendages. 

The general features of the cylinder of secondary 

wood as seen in transverse section are shown in plate 

30, figures 1 and 2, and as seen in longitudinal section 

in plate 32, figure 3. A marked similarity to Oalamopitys americana Scott and Jeffrey 16 is at once seen. 

Except· at the angles 

this secondary xylem 

abuts directly on the 

pith. The rays, it 

will be noted, are 

several cells in width. 

Outside of the wood 

is a zone of crushed 

and otherwise distorted and poorly preserved tissue of variable extent. The lumens are clogged, and 

it is impossible to 

determine accurately 

the nature of the elements. However, 

FIGURE 9.-Camera lucida sketch of a transverse section of Diichnia kentuckiensis show· 

ing the more obvious features of the stem. 

Note the large five-angled pith and the double 

leaf traces. 

the logical interpretation is that this zone includes 

the can1bium, phloem, and pericycle. On the exterior is the cortex, consisting of a thick large-celled 

area but slightly differentiated except near the outer 

surface, where occur hypodermal sclerotic strands of 

the type generally called "sparganum cortex." Here 

and there are lysigenous cavities which suggest secretory centers. At several points in text figure 9 will be 

noted paired lateral organs. These can be interpreted 

only as the vascular bundles of emerging leaf traces. 

These traces are double, and their divergence as indicated by successive transverse sections is 2/5. 

The pith.-The general aspect of the tissue occupying 

the central area of the stem is clearly shown in plate 

30, figures 1 and 2, and in plate 32, figure 2. This 

pith, if it may be called such, is large and five-angled. 

The groundmass is parenchymatous, consisting of 

nearly isodiametric cells, as is indicated by comparing 

the complementary sections illustrated in plate 30, 

figure 2, and plate 32, figure 1. The walls of these 

16 Scott, D. H ., and Jeffery, E. C., On fossil plants, showing structure, from the 

base:of the Waverley shale of Kentucky: Roy. Soc. London Philo:;. Trans., ser. 

B, vol. 205, pp. 317-3301 1914. 
152 SHORTER .CONTRIBUTIONS TO GENERAL GEOLOGY 1934-35 

elements are unusually thick. This is to be regarded 

as a peculiarity of preservation rather than a feature 

indigenous to the original tissue. Occurring occasionally are canals which appear to be of secretory 

function and lysigenous origin. Several of these are 

shown in plate 30, figure 2. Also there are certain 

cells and aggregates of cells that are filled with a dark, 

gummy substance. 

Rather commonly, as is indicated in plate 30, figure 

4, there are "nests" of elements which resemble 

tracheids. In plate 32, figure 1, several of these are 

shown in longitudinal section, and it is at once seen 

that these are very elongate. A careful exa~ination 

of these elements has failed to reveal any evidence of 

mences to pass out to a leaf the primary bundle at the 

pith angle involved shifts outward to the inner margin 

of the secondary wood. At the same point it elongates radially, as is indicated in plate 30, figure 1, and 

plate 32, figures 3, 7, and 8. The protoxylem divides 

into two strands, and finally separate bundles of primary xylem result, the outer passing into the leaf and 

the inner remaining in the stem as a reparatory bundle 

(pl. 32, fig. 4). -

Secondary wood.-The secondary xylem of Diichnia 

kentuckiensis abuts directly on the pith except at .the 

angles, and at those points it comes into direct contact 

with the primary xylem only in connection with an 

emerging leaf trace. The general features of this cylinder are shown in plate 30, figures 1-3; plate 

31, figure 3; and plate 32, figures 3, 5, and 7. 

The structure is very similar to that of 

CC!lamopitys americana. The medullary rays 

are numerous and vary in width from 1 to 

8 cells. By far the larger number are multiseriate. As shown in plate 3, figure 1, these 

rays are wider in the immediate proximity 

of the pith. There the ray cells are nearly 

isodiametric or square, but farther out they 

become radially elongated. 

Although the preservation of the material 

is such that the suite of longitudinal sections 

is very unsatisfactory to study, it has been 

possible to obtain some information concerning the nature of the pitting in the tracheids. In general the pits are small and 

multiseriate, their outline being hexagonal, 

owing to their alternate arrangement. This 

is quite in apcord with .t,he observations 

made by Scott. and Jeffrey on Calamopity~ 

americana. 

Phloem and pericycle.-On the exterior of 

the, secondary wood is a thin zone of poorly 

. 'pres_erved ' .parenchyma, which IS sho~ in' 

plate 31,fig'ures 1 arid 3,andplate 32~figure7_- Little.can 

be said. of this tiss~e,· 'owing to its collapsed condition 

and the clogged lumens~ However, it may be interpreted as being the remains of the cambium, phloem, 

and pericycle. Certain features of this tissue are of 

interest. A considerable quantity of secondary phloem 

was apparently developed, as is suggested by the 

radially arranged elements adjacent to the wood. 

The rays of the secondary xylem continued into the 

phloem for some distance, as is indicated in plate 32, 

figure 7. 

FIGURE 10.- Camera lucida sketches showing the origin and course of the leaf strands in Diichnia 

kentuckiensis. See text for explanation. 

pitting, but there can be little doubt concerning the 

identity of these as tracheids embedded in the pith. 

In this respect Diichnia kentuckien~is ·resembles 

Calamopitys americana Scott and Jeffrey, which has a 

"mixed pith" so ligneous as to approach a typical 

protostelic condition. 

Primary xylem.-The primary xylem strands in 

Diichnia kentuckiensis are situated, as is indicated in 

plate 30, figures 1 and 2, and diagrammatically in text 

figure 9, at the angles of the pith and in 'consequence 

are well separated. (A few strands are likewise present in the body of the pith, but the present discussion 

is restricted to the circum-medullary ones.) Except 

in the vicinity of a departing leaf trace these strands are 

very .uniform in size, eccentrically mesarch, and 

separated by a few cells of parenchyma from the 

secondary wood. However, where a strand comCortex.--The thick cortex of Diichnia kentuckiensis 

is composed chiefly of thin-walled, isodiametric cells of 

parenchyma (pl. 31, fig. 1; pl. 32, fig. 5). On the exterior there is a "sparganum" zone consisting of radiating strands of alternately sclerotic and thin-walled 

tissue1 as is shown in plate 3·2, figures 5 and 6, and plate 
FLORA OF THE NEW ALBANY SHALE, PART 1 153 

31, :figure 3. A hypoderm of this type is common in 

the less woody members of the Calamopityeae. 

Here and there cavities of apparently lysigenous 

origin are found in the cortex. These are apparently 

secretory, although no evidence of gum deposits was 

observed. Similar" canals" lie in the parenchymatous 

portion of the mixed pith. 

Leaf trac~.-In the features so far enumerated and 

discussed nothing has been observed which indicates 

that Diichnia kentuckiensis is a particularly significant 

type. In fact, it may be safely said that apart from 

its organization in the vicinity of the node the structure 

is of little interest. However, the n10de of origin and 

development of the leaf traces introduces several 

peculiarities which have not been previously recorded 

in the family. 

To insure clarity a series of diagrammatic drawings 

have been prepared (fig. 10) from sections that illustrate the stages in the departure of the traces. These 

will be referred to in the discussion of the general 

features of the bundles, and the details of structure 

will be illustrated in the plates. 

ln.plate 30, figure 1, are shown two primary bundles 

that have become tangentially elongated. Thes~, it 

will be ob;;_erved, are at adjacent angles of the pith. 

Se-parating them is a considerable expanse of seconqary 

xylem in .direct ~ontact with the parenchyma ous 

central area. Plate 32, figure 8, illustrates on~ of 

these bu~ulles at a higher magnification. The pr toxylem isclearlydivided into inner and outer groups, nd 

the inner appears to have undergone further diviswn. 

A slightly more advanced stage is represented diagrammatically in text figure 10, a. Theprimaryxylem 

of each of the two strands has divided into two roesarch bundles, of which the inner ones are reparatory 

strands and the o:uter the leaf-trace strands. This 

stage is· show~ . in more detail in plate 31, figure 4, 

plate 32, figure 4, and plat~ 33, figures 2 and 4. It 

will be-noticedthat the xylem. of the reparatory strands 

is quite eccep.tricJilly 'mesarch, approaching endarchy. 

In the specimen shown in pla-te 32, figure 4, a further 

division .in the reparatory strand has taken place. 

The primary xylem o_f the leaf trace is, however, 

centrally mesarch. 

A more advanced stage in the development of the 

trace is shown in text figure 10, b, supplemented by 

plate 30, figure 2, and the intermediate stage shown in 

plate 30, figure 3. Before discussing these in detail 

one very striking feature must he brought out. There 

is .a very noticeable lag in the anodic bundle. That is 

to say, the kathodic bundle is considerably in adv nee 

of the other, particularly in the early stages. T s is 

very plainly brought out in text figure 10, h. As 

these two bundles, which comprise the leaf tr ce, 

pass from the stele they consist of mesarch pri ary 

xylem and a considerable amount of secondary xyl m. 

In the earlier stages the secondary xylem is obviously 

restricted to the abaxial position. However, as the 

trace emerges from the wood, secondary xylem likewise appears on the adaxial side, so that the bundleS' 

have a radial arrangement similar to that which might 

be expected in a small branch, though for obvious 

reasons the view that they represent such a branch is 

untenable. The general appearance of these bundles 

is shown in plate 33, figures 5 and 6. It is clear th~t 

the centrally located primary xylem is mesarch. However, the protoxylem groups are several, in anticipation of further division of the bundles. These divisions 

may take place before the strands emerge from the 

secondary wood. The long axis of the primary wood 

is tangential. 

The two bilndles retain their concentric structure for 

some distance as they ascend and gradually pass out 

into the cortex. Their course is only a slight departure from that of the parent axis, as is indicated in 

text figure 10, c and d. They gradually become more 

and more tangentially flattened, however, and after 

they pass into the cortex the secondary xylem is lost, 

first on the abaxial and finally on the adaxial side. At 

the same time, the expanse of primary xylem increases. 

The tissues that are interpreted as phloem thin in the 

same manner, but a narrow zone is retained on the 

inner side and a somewhat broader one on the out~r. 

Tangential elongation of the metaxylem continues 

with the development of several protoxylem groups. 

These stages are illustrated in text figure 10, <i and e, 

and in plate 31, figures 1 and 3. 

Leaf base.-In the later stages in the development of 

the leaf trace there are seen numerous divisions of the 

original bundles, an indeterminate number of smaller 

·ones resulting (text fig. 10, f; pl. 33, fig. 3). The 

structure of these divisions is mesarch; the phloe~, 

though thickest on t:P,e abaxial surface, appears to be 

present on the adaxial surface also. 

These bundles retain their orientation with the long 

sectional axis tangential, as is clearly brought out in 

text figure 10, f. Unfortunately, later stages than this 

have not been observed in the material at hand, so it 

is impossible to determine accurately the nature of the 

actual petiole. Some suggestion of the structure that 

might be expected is found in the organ described by 

Scott and Jeffrey 17 a$ Calamopteris hippocrepis a~d 

simila1· ones frmn Thuringia referred to C. debilis 

Unger. 18 These ~ave been interpreted as the petioles 

of some forms allied to Calamopitys but as yet unknown. 

They resemble Kalymrna in their general .. ,organization 

but differ in the more marked collaterafstructure of the 

bundles and the tendency for these .. bundles to ~e 

tangentially elongated (very pronounced in C. hipifocrepis), in contrast to tb.e radial elongation in Kalymma. 

11 Scott, D . H., and Jeffrey, E. C., op. cit., pp. 33Q-335, 1914. 

IS Unger, Franz, op. cit., p. 53[13~], pl. 2, fig. 2; pl. 8, fig. 121 1856, 
154 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY 1934-35 

In view of the fact that Calamopteris is known from 

the same locality and horizon as Diichnia kentuckiensis, 

it is by no means unlikely that they represent petiole 

and stem of the same plant. · This is to be taken as no 

more than a suggestion, without any satisfactory proof. 

of connection. 

To summarize, the features which serve to characterize Diichnia kentuckiensis are these: 

1. The broad five-angled pith with occasional strands 

ofxylem and lysigenous canals. 

2. The widely spaced mesarch bundles of primary 

xylem. · 

3. The broad-rayed secondary xylem abutting directly on the pith except in the vicinity of the angles. 

4. The double leaf traces, the two bundles originating from adjacent primary xylem bundles at adjacent 

angles of the pith. 

5. The tangential instead of radial elongation of the 

bundles after they have begun to divide in the cortex. 

6. The 2/5 divergence of the leaves. 

REL~ TIONSHIPS OF DIICHNIA 

The several species· referred to the genus Calamopitys fall naturally into two groups, which have been 

designated Eu-Calamopitys 19 and Eristophyton. 20 These 

genera or subgenera, as they are variously regarded, 

have been briefly contrasted above. Though differing 

somewhat in the structure of the primary wood, and 

more decidedly in the structure of the secondary wood, 

one feature in common is the originally monarch condition of the leaf trace. ·This has, in fact, been consider.ed by some investigators a character of generic 

v:alue. Clearly any tendency toward diarchy is a 

distinct advance of cardinal importance. 

·It has been shown that Diichnia kentuckiensis in 

the internodal regions shows anatorical features 

which unite it closely with Eu-Calamopitys. Minor 

differences exist, but they are of no more th&n specific 

worth. In the vicinity of the nodes, however, it 

becomes at once apparent that the stem departs 

widely from the definition of Calamopitys~ The 

~~af traces are clearly double, the two bundl~s departrng from adjacent angles of the five-rayed pith. Furthermore, the leaf base does not appear to conform 

closely with Kalymma, the known petiole of other 

species of Oalamopitys in which that organ has been 

found attached. Instead it more nea,:Hy resernbles 

Calamopteris. 

·· These departures from the morph0logic features 

typical of Calamopitys, to which Diichnia kentuckiensis 

shows the closest affinities, can be interpreted as a 

distinct and important advance. The question of the 

degree of separation from Eu-Calamopitys therefore 

becomes critical. As is indicated by tl;le_ name 

1g Scott, D. H., Studies in fossil botany, pt. 2, pp. 108-109, 19'23. 

ao Zalessky, M.D., op. cit., p. 27, 1911. 

already used, the writer prefers to make this separa .. 

tion generic. As the genus cannot be placed in any of 

the segregates that have so far been proposed, it 

becomes necessary to erect a new group. For this 

genus the name Diichnia is proposed, and the type is 

to be regarded as D. kentuckiensis. The characters 

to be used in delimiting the segregation have been 

pointed out in the description of the species. Of 

particular importance is the diarch leaf t:r:ace. Likewise the pattern of the leaf base, which is similar to 

that des~ribed as Calamopteris, may afford a criterion 

for separation from Eu-Calamopitys, which shows the 

. Kalymma structure in the petiole. 

The question of relationships is one which the 

writer hesitates to discuss at any great length, for 

obvious reasons. A few generalizations based on the 

more significant features of Diichnia kentuckiensis 

may, however, be stated with a fair degree of accuracy. 

In Eu~Calamopitys there is a definite trend in the direction of a diarch leaf trace. This is very ·well illustrated in the two species, Calam,opitys saturni Unger 

and 0. americana Scott and Jeffrey.21 It has been 

pointed out that in the first of these the leaf trace 

passes through the wood as- a single bundle and 

divides only after it has reached the cortex. In 0. 

americana the strand of xylem divides as it passes 

through. the secondary wood, the two bundies being 

quite distinct by the time the cortex is reached. 

It is not out of place at this point to mention the 

exactly parallel case found in the family -Lyginopterideae, genus Heterangium. In Heterangium grievii, 

from Pettycur, Scotland, the leaf trac·e is at first 

monarch, but the protoxylem divides it1~6 two after 

leaving the stele. Division of the bunille does not 

take place, however, until the vicinity o{ the rachis is 

reached. In certain other species segregated by Scott 

in Eu-Heterangium there is a somewhat earlier division 

of the trace, but it remains primitively monarch. In 

the other segregate, Polyangium, the leaf trace is 

double _'where it leaves the stele and undergoes numerous divisions while in the cortex. 22 

The situation which has just beeli outUned in 

Heterangium is exactly analgous to tha't in the Calamopityeae, where Diichnia kentuckiens.is ~hows a 

double leaf trace and apparently occupies the same 

position relative to Eu-Oalamopitys that· P6lyangium 

occupies relative to Eu-Heterangium. 

Another feature which Diichnia kent'l_fckiensis exhibits and which is suggestive of anatomical advance 

over most species of Eu-Calamopitys is the tinusually 

slight amount of primary xylem grouped in v~ry 

discrete bundles. Calamopitys americaniL and 0. 

annularis are characterized by nearly or qu~ro contin21 Scott, D. H., Notes on Calamopitys Unger: Linnean Soc. Lmid<JilJour., Botany, 

vol. 44, no. 297, pp. 205-232, 1918. 

n Scott, .D. H., The Heterangiums of the British Coal Measilres: Linnean Soc. 

London Jour., Botany, vol. 44, no. 295, pp. 91-92, 1917. 
FLORA OF THE EW ALBANY SHALE, PART 1 155 

uous primary xylem. Oalamopitys saturni rese 

Diichnia kentuckiensis closely in the meager qu ntity 

of prin1ary xylem. · 

The structure of the petioles, if it is accepte that 

Oalamopteris is that organ in Diichnia kentucki nsis, 

is of negative value in speculating on the relatio ships 

of the species. Clearly the two types are dis inct, 

but whether Oalamopteris shows structural adv nces 

over Kalymma is a question that cannot be ans ered 

by the writer. 

CONCLUSIONS 

The observations tha~ have been made on Di chnia 

kentuckiensis may be summarized as follows: 

1. Diichnia kentuckiensis is a stem from th late 

Devonian strata of Kentucky presenting nu erous 

features which ally it with species grouped in EuOalamopitys by Scott. 

2. The double leaf trace, which is a conspicuous 

feature of the plant, is a structure that renders Diichnia 

kentuckiensis distinct from any previously described 

form. 

3·. The lea( trace exhibits characters which suggest 

that Oalamopteris may have been the petiole. 

4. On the basis of the diarch traces a new genus, 

Diichnia, is proposed for stems conforming to Diichnia 

kentuckiensis. The definition of Eu-Oalamopitys describes the leaf trace ~s sjngle at the point of origin. 

5. The guarded opinion is expressed that through 

diarchy and reduction of primary xylem Diichnia 

kentuckiensis shows' distinct advances over the 

related species of Oal(fmopitys (Eu-Oalamopitys). 

, PLATES 30-33 

157 
PLATE 30 

Diichnia kentuckiensis, n. gen. and n. sp. 

FIGURES 1, 2. General view of the central axis of a stem showing the five-angled "mixed" pith and the position of the primary 

wood. Note the secretory canals occurring in the parenchymatous portion of the pith. X 7. 

FIGURE 3. A portion of a transverse section showing the departure of the double leaf trace. X 7. 

FIGURE 4. A portion of the central mixed pith ·showing the tracheids, which are scattered throughout the mass. X 60. 

FIGURE 5. A single primary xylem bundle in a position indicating close proximity to an emerging leaf trace. Note that the 

primary xylem, which normally is separated from the secondary wood by a few cells of parenchyma, is here 

directly in contact with those elements. X 60. 

158 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 185 PLATE 30 

1 2 

3 

4 5 

DIICHNIA KENTUCKIENSIS READ. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 185 PLATE 31 

1 2 

3 4 

DIICHNIA KENTUCKIENSIS READ. 
PLATE 31 

Diichnia kentuckiensis, n. gen. and n. sp. 

FIGURES 1, 3. A portion of a stem in transverse section showing the stele from which two bundles of a single leaf trace have departed 

from adjacent an_gles of the pith occupied by bundles of primary wood. Note the tangentially elongate leaf-trace 

bundles in the cortex. X 7. 

FIGURE 2. Transverse section showing one bundle of the double leaf trace directly after it has emerged from the secondary wood. 

Note the reparatory strand in the pith and the nearly perfect radial symmetry of the leaf-trace bundle. X 24. 

FIGURE 4. Transverse section of a portion of the primary and secondary wood and adjacent tissues showing the departure of a 

leaf-trace strand. Note the isolated reparatory bundle. X 35. 

159 
PLATE 32 

Diichnia kentuckiensis, n. gen. and n. sp. 

FIGURE 1. Radial section of the "mixed" pith showing the occurrence of medullary tracheids. Note the nature of the parenchymatous tissue. X 30. 

FIGURE 2. Radial section of the whole stem. X 7. 

FIGURE 3. Transverse section showing division of primary bundle into a leaf-trace strand and a reparatory strand. X 35. 

FIGURE 4. Transverse section showing the leaf trace and reparatory strands separate in the immediate vicinity of a node. X 35. 

FIGURE 5. General view of a transverse section of Diichnia kentuckiensis showing the characteristi~ five-angled pith, the woody 

cylinder, the broad cortex with· radial hypodermal strands, and the leaf traces e~bedded in the cortex. X 7. 

FIGURE 6. Tangential section of the hypodermis showing the alternation of sclerenchyma and parenchyma. X 30. 

FIGURES 7, 8. Transverse sections of primary bundles and adjacent tissues at the origin of leaf-trace. strands. X 24. 

160 
U. S. GEOLOGICAL SURVEY 

6 7 

DIICHNIA KENTUCKIENSIS READ. 

PROFESSIONAL PAPER 185 PLATE 32 

8 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 185 PLATE 33 

1 2 

5 6 

DIICHNIA KENTUCKIENSIS READ. 
PLATE 33 

Diichnia kentuckiensis, n. gen. and n. sp. 

FIGURE 1. A single bundle of the leaf trace as it appears in the middle cortex before division. X 24. 

FIGURES 2, 4. Transverse sections of departing leaf-trace strands. Observe the reparatory bundles embedded in the outer pith. X 24. 

FIGURE 3. A portion of a leaf trace in the cortex after division has taken place. x· 24. • 

FIGURES 5, 6. Transverse sections of leaf-trace bundles as they appear just after emerging from the secondary xylem. Note the 

concentric structure. X 24. · 

161 

0