Amer. J. Bot. 74(11): 1750-1757. 1987.

A WOODY LYCOPSID STEM FROM THE NEW ALBANY SHALE (LOWER MISSISSIPPIAN) OF KENTUCKY1

2 3 MICHAEL A. CICHAN ,4 AND CHARLES B. BECK -Department of Botany and Microbiology, Arizona State University, Tempe, Arizona 85287; and 'Museum of Paleontology and Department of Biology, University of Michigan, Ann Arbor, Michigan 48109

ABSTRACT A lycopsid axis from the New Albany Shale (Sanderson Formation) ofKentucky is described. The stem, which branches dichotomously, is 45 mm in diameter and is characterized by a relatively narrow parenchymatized protostele, a 3.0 mm-thick cylinder of secondary xylem, a tripartite cortex, and a periderm that is more than 5.0 mm thick. The secondary xylem is composed of uniseriate and biseriate vascular rays and narrow tracheids with scalariform wall thickenings on both radial and tangential walls. The periderm is characterized by elongate, thick-walled cells, some of which broaden tangentially in the outer part of the tissue forming zones that appear wedge-shaped in cross section. Surface features of the axis, including leaf bases, are not preserved. The stem is tentatively regarded as a member ofthe Lepidodendrales in accordance with the numerous anatomical characters that it shares with more recent rep­ resentatives ofthe order. Because the external morphology is not known, however, the possibility exists that the axis corresponds to a protolepidodendralean taxon currently known only from compression and/orimpression remains or some othernonlepidodendralean plant that produced secondary xylem. The extremely narrow profile of the secondary xylem tracheids (relative to other arborescent lycopsids) is interpreted as evidence that the plants grew in a habitat that was substantially drier than the Upper Carboniferous coal swamps.

THE LEPIDODENDRALES is an extinct order of curredpriorto the invasion ofthe coal swamps. arborescent lycopsids known primarily from The group reputedly arose during the late De­ Carboniferous fossils. Stems included within vonian from plants with a Lepidodendropsis­ this order exhibit unique, helically arranged type morphology (Thomas, 1978), and it has leaf cushions and histologically distinct sec­ been suggested that Valmeyerodendron, Cy­ ondary xylem and periderm. Coincident with clostigma, and Lepidosigillaria represent mor­ the formation of coastal peat swamps during phological intermediates between the Upper the early part of the late Carboniferous, the Devonian plants and the more massive Upper lepidodendraleans underwent a period of ex­ Carboniferous representatives (Stewart, 1983). tensive diversification, becoming one of the Most ofthe uncertainty surrounding the early dominant vascular plant groups of the Upper evolution of the Lepidodendrales can be at­ Paleozoic. The plants were exceptional in size, tributed to the scarcity of anatomically pre­ number, and morphology and occupied a va­ served fossils from the late Devonian and ear­ riety ofecological zones within the coal swamps liest Carboniferous. Although compression and (DiMichele and Phillips, 1985); the obvious impression material from these times is known evolutionary success ofthe group has been at­ in some detail (Jennings, 1972; Chitaley, 1982) tributed to the presence of a suite of unusual and has provided important information rel­ vegetative (DiMichele and Phillips, 1985; Ci­ ative to stem morphology, anatomically pre­ chan, 1985, 1986) and reproductive (Phillips, served axes are generally required to unequiv­ 1979; Thomas, 1981) features. ocally determine the presence of secondary Despite the fact that the Lepidodendrales is tissues and thus establish lepidodendralean af­ one of the best-understood plant taxa of the finities (Thomas, 1978; DiMichele, 1983). Carboniferous, relatively little is known about In this contribution, a permineralized ly­ the early evolutionary history ofthe group, in copsid stem from the New Albany Shale (Low­ particular the phylogenetic events that oc- er Mississippian) ofKentucky is described. The axis exhibits relatively thick zones of second­ I Received for publication 29 December 1986; revision ary xylem and periderm, both of which are accepted II March 1987. histologically similar to tissues found in sig­ The research was supported in part by funds provided by the National Science Foundation (BSR-8614588) to nificantly younger members of the Lepido­ MAC. and (DEB-8001803) to C.B.B. dendrales. In this respect, the axes represent • Michael Cichan died August 16, 1987. the oldest, certifiably woody lycopsid fossils

1750 November 1987] CICHAN AND BECK - MISSISSIPPIAN LYCOPSID 1751 about which published information currently gential walls. The tracheids are polygonal in exists (but see Cai and Qin, 1986) and, thus, cross section, with a mean diameter of 42 ~m are likely to be important in understanding the (SD = 10 ~m, N = 75). Tracheids near the early evolution oflepidodendralean lycopsids. periphery ofthe xylem cylinder are noticeably The fossils are also significant in that the sec­ smaller and presumably represent the proto­ ondary xylem tracheids are three to four times xylem elements. There is no evidence ofa pro­ smaller than those in woody lycopsids from toxylem corona (Fig. 1). the Upper Carboniferous. Based on the rela­ tionship that seems to. exist between tracheid Secondary xylem- The secondary xylem size and edaphic conditions at the growth site, cylinder (Fig. 1, 2) is ca. 3.0 mm thick and is this distinction is likely to be important in characterized by elongate tracheids, thin-walled evaluating the ecological characteristics ofthe ray cells, and leaf traces that are terete in tan­ source region of the New Albany Shale flora. gential sections (Fig. 3,4). The mean tangential width oftracheids in the middleand outerparts ofthe wood is 39 urn (SD = 6.0 ~m, N = 75); MATERIALS AND METHODS- The description tracheids in the innermost wood are substan­ is based on five calcium phosphate perminer­ tially narrower. Scalariform thickenings occur alizations collected from the Falling Run on both the radial and tangential walls of the Member ofthe Sanderson Formation, New Al­ elements (Fig. 3, 5). In general, the preserva­ bany Shale (Lower Mississippian) near Boston, tion of the wood is poor, and "Williamson KY (Nelson County, Mercator grid coordi­ striations" could not be resolved in either pri­ nates-85°38'50" by 37°45'). The beds have mary xylem or secondary xylem tracheids. been tentatively dated as early Tournaisian Vascular rays are mostly uniseriate and bise­ (?Tnlb) (Scott, Galtier, and Clayton, 1984), riate and range from one- to ca. eight-cells high and, as such, the flora from these deposits is (Fig. 3). Within the wood, leaftraces follow a slightly older than that from the Montagne horizontal or slightly inclined radial course and Noire locality of France (mid- to late Tour­ are arranged in a low helix about the axis. At naisian Tn2b-Tn3c). Two ofthe fossils (P-l 783, one site the leaf traces appear to be whorled. P-1784), which apparently represent parts of the same axis, are roughly cylindrical and mea­ Branching-In one of the specimens, two sure ca. 4.5 em in both length and diameter. xylem cylinders are present, characterized by At the macroscopic level, the axes consist ofa both primary and secondary xylem. The two xylem core surrounded by several concentric cylinders are essentially equal in diameter (ca. layers oftissue. The other specimens are small­ 6.0 mm) and diverge from one another at an er pieces ofa fragment that had previously been angle of approximately 40 degrees. The spec­ cut into three parts (P-1788, P-1789, P-1790); imen is interpreted as a region of the stem at each piece measures ca. 1.5 x 2.0 x 2.5 em. a level where the vascular tissue divided in The original fragment consisted ofaxylem cyl­ association with branch formation. The nearly inder and some extraxylary tissue at the level equal size ofthe two xylem cylinders suggests of an apparent isotomous dichotomy. Cross­ that the branching pattern ofthe stem was iso­ and longitudinal sections of the material were tomous. prepared using the technique described by Stein, Wight, and Beck (1982). Tracheid and peri­ Cortex andperiderm- Mostofthe tissuejust derm cell widths were measured at the widest peripheral to the secondary xylem cylinder, a part of the individual cells in tangential, lon­ zone ca. 3.0 mm broad and conforming po­ gitudinal sections. All slides and fossil frag­ sitionally to the phloem and inner cortex, is ments are currently housed in the Paleobotan­ not preserved. As such, a description of this ical Collections, Cleveland Museum ofNatural tissue is not possible with the material at hand. History, Cleveland, OH. A broader zone ca. 7.0 mm thick surrounds the vacuous region and presumably represents DESCRIPTION-Stele-The axis is character­ the middle cortex. The cells of this zone are ized by a parenchymatized protostele, with a relatively large (mean tangential width = 144 primary xylem cylinder that measures ca. 1.2 ~m, SD = 47 ~m, N = 75), parenchymatous, mm in diameter(Fig. 1).A central cavity, which and irregular in shape (Fig. 6). Beyond this is presumably represents the remains ofthe pith, the outer cortex, a narrow (3-5 cell layers) band is present and measures ca. 0.3 mm in diam­ of tissue contiguous with the inner margin of eter. The primary xylem cylinder (Fig. 1) is ca. the periderm (Fig. 7). The cells that comprise 0.5 mm thick and is characterized by tracheids this region are parenchymatous in appearance with scalariform thickenings on radial and tan- and more or less rectangular in shape (mean 1752 AMERICAN JOURNAL OF BOTANY [Vol. 74 November 1987] CICHAN AND BECK - MISSISSIPPIAN LYCOPSID 1753 tangential width = 93 ~m, SD = 29 ~m, N = et aI., 1984), the axes represent the oldest per­ 75). The long dimension of most of the cells mineralized lepidodendralean vegetative re­ is oriented longitudinally. mains currently known. The well-developed periderm (ca. 6.0 mm Anatomically preserved stems of nonlepi­ thick) is divisible into two relatively distinct dodendralean lycopsids, where known, are typ­ zones (Fig. 7). The innerofthe two is composed ically rather slender, and rarely exhibit evi­ of radially aligned cells that are square-rect­ dence ofextensive secondary growth. A notable angular in cross section. The cells are relatively exception is the isoetalean genus Chaloneria thin-walled like those of the outer cortex and Pigg and Rothwell, in which parts ofthe stems exhibit a mean tangential width of 66 ~m are characterized by a parenchymatized pro­ (SD = 16 ~m, N = 75). These cells grade almost tostele and moderate amounts ofperiderm and imperceptively into the thick-walled cells of secondary xylem (Pigg and Rothwell, 1983). the outer periderm (Fig. 7). In this region the The primary xylem cylinder in Chaloneria, cells are ca. 10 times longer than wide (mean however, is dissected by parenchymatous plates length = 308 ~m, SD = 82 ~m, N = 57; mean and, thus, is distinct from that in the New tangential width = 31 ~m, SD = 7 ~m, N = Albany Shale material. In protolepidodendra­ 75) and have tapering ends (Fig. 8-10). Near lean lycopsids, some ofwhich are presumed to the periphery ofthe periderm, the files ofthick­ have been arborescent, the stems, where known, walled cells are divided into radially arranged are characterized either by lobate protosteles groups by wedge-shaped zones ofcells that are (Colpodexylon-Banks [1944]) or by protosteles substantially broader than the fiber-like cells that are triangular or terete in cross section, (Fig. 8), resulting in the formation of"fissures" with prominent longitudinal ridges (Protolep­ (Eggert, 1961; DiMichele, 1983) or "meshes" idodendron-Banks [1944]; Grierson and Banks (Kisch, 1913). Cells that compose the wedges [1963]). As such, the anatomy of the lycopsid are aligned in somewhat irregular radial files; axes described herein is unlike that ofany pro­ the cells increase in tangential width near the tolepidodendralean stems reported to date. It periphery ofthe axis (Fig. 8-10) and some be­ is important to note, however, that a large come longitudinally subdivided (Fig. 10). The number of protolepidodendralean species are broad cells occur in the same files as the narrow currently known only from compression and cells, indicating that the former were derived impression remains, and that the New Albany ontogenetically from the latter. In this respect, Shale lycopsid mayactually be an anatomically the narrow, fiber-like cells appear to have de­ preserved form of one of these taxa. In this differentiated to form the broad cells and thus regard, Cai and Qin (1986) describes a partially must have been alive at maturity. permineralized lycopsid axis from the Upper Devonian of China that he interprets as Lep­ DISCUSSION - Taxonomy - Based on our tophloeum rhombicum with secondary xylem. current understanding offossil Lycopsida, the One of us (CBB) has had the opportunity to axes described in this report are most similar examine this material and agrees that second­ to those presently included in the order Lep­ ary xylem is present. idodendrales. In the absence of information Anatomically preservedlycopsid stems from pertaining to leafbases, this assignment is made the Lower Carboniferous that can confidently in accordance with the appearance ofthe stele, be assigned to the Lepidodendrales are rare. the presence ofsignificant amounts ofperiderm Early studies of the New Albany Shale flora and secondary xylem, and the distinctive sea­ (Read, 1936; Read and Campbell, 1939) re­ lariform thickening of the primary xylem and sulted in the description of several perminer­ secondary xylem tracheid walls. Assuming that alized axes that were classified as lepidoden­ this assignment is accurate, and in view ofthe dralean, including Lepidodendron boylensis proposed early Toumaisian age ofthe deposits Read, Lepidodendron novalbaniense Read and from which the material was collected (Scott Campbell, and Lycopogenia callicyrta Read.

+- Fig. 1-6. 1. Cross section of primary xylem (left) and secondary xylem (right). Pith is at arrow. PI789b no. I, x41. 2. Cross section of secondary xylem. Inner xylem is at top. Note files of tracheids and rays. PI789b no. I, x 104.3. Tangential section of secondary xylem showing uniseriate rays (arrows) and tracheids with scalariform wall thickenings. PI789c side no. 2, x 104. 4. Tangential section of secondary xylem. Note three leaf traces (arrows). PI789c side no. 8, x 41. S. Radial section ofsecondary xylem showing two rays and tracheids with scalariform wall thickenings. PI789c side no. 5, x 104. 6. Cross section of parenchymatous middle cortex. PI788a no. I, x 104. 1754 AMERICAN JOURNAL OF BOTANY [Vol. 74

Fig. 7-10. 7. Cross section of outer cortex (bottom) and inner periderm (top). Note gradual transition from large, thin-walled cells to relatively small , thick-walled cells arranged in radial files. PI784a no. 4, x41. 8. Cross section of outer periderm (outer periphery at top) showing radial files of large-diameter parenchyma cells continuous with those of thick-walled periderm cells. PI784a no. 4, x 104. 9. Tangential section of periderm. Note that tissue is composed of elongate , thick-walled cells. PI784a side no. 3, x 95. 10. Tangential section ofouter periderm showing large-diameter parenchyma cells (center). PI784a side no. 3, x 95.

These stems are all rather small (ca. < 2 ern in is likewise characterized by a terete protostele diameter), with a slender protostele (ca. 1-2 and a broad tripartite cortex. The middle por­ mm in diameter), a thick parenchymatous cor­ tion of the cortex is composed of irregularly tex , and little or no evidence of secondary shaped parenchyma cells traversed by strands growth. External features ofthe stems (i.e., leaf ofradially elongate cells. Thin zones ofparen­ cushions) are not preserved. Phytokneme rho­ chyma cells in radial files are present near the dona (Andrews, Read, and Mamay, 1971), a inner and outer margins of the outer cortex, lycopsid axis also from the New Albany Shale, and a narrow (2-4 cells thick) band of tissue November 1987] CICHAN AND BECK-MISSISSIPPIAN LYCOPSID 1755 interpreted as secondary xylem surrounds the more derived, Upper Carboniferous taxa. De­ primary xylem cylinder. Vascular rays, how­ finitive statements regarding the taxonomic ever, have notbeen demonstratedin this tissue. placement of the specimens must await the At present, there is no anatomical evidence discovery of better-preserved material. indicating that the specimens reported in this study correspond to the proximal parts ofany Ecology-The results of recent work on ofthe previously described New Albany Shale functional aspects of wood anatomy in Car­ lycopsids. The stems lack both the "scalloped" boniferous plants (Cichan, 1986) indicate that outline of the stele in Lycopogenia callicyrta the general correlation between xylem anato­ and Lepidodendron novalbaniense and the dis­ my and ecology in extant seed plants (e.g., tinctive histology of the cortex in Lepidoden­ Carlquist, 1977) may also apply to fossil gym­ dron boylensis and P. rhodona. It is important nosperms and woody pteridophytes. Within a to note, however, that the figures and abbre­ given lineage, secondary xylem tracheid di­ viated text that accompany the descriptions of ameter may be a general indicator of edaphic L. novalbaniense, and L. callicyrta, are insuf­ conditions, with broad tracheids occurring in ficient to permit precise comparison ofcortical plants from mesic habitats and narrow ele­ features. In this respect, a critical reevaluation ments occurring in plants from more xeric re­ of the "herbaceous," New Albany Shale ly­ gions. In lepidodendraleans from the Middle copsids is in order, particularly with regard to Carboniferous coal swamps, secondary xylem the results of recent work by Meyer-Berthaud tracheids typically exhibit mean widths in ex­ (1984) on the nonlepidodendralean lycopsids cess of 100 /-Lm (Williamson, 1872; Pannell, from the Tournaisian of Europe. 1942; Felix, 1952; Cichan, 1985), and in some The woody stems described in the present specimens of Lepidodendron kansanum, tra­ work correspond most closely to a suite oflep­ cheids are more than 200 /-Lm wide (Felix, 1952). idodendralean axes from the Lower Carbon­ In contrast, secondary xylem tracheids in the iferous of Europe, including Lepidophloios New Albany Shale axes average less than 40 wiinchianus (Seward and Hill, 1900; Walton, urn wide. Thus, if the proposed relationship 1935), Lepidophloios scottii (Gordon, 1908), between tracheid width and environmental and Lepidophloios kilpatrickensis (Smith, 1962) conditions can be extended to include fossil and also Lepidodendron johnsonii from the groups, it is likely that the New Albany Shale Lower Pennsylvanian of Colorado (Arnold, axes grew in a locality that was substantially 1940). These protostelic axes are all charac­ drier than the Upper Carboniferous coal terized by a broad, parenchymatous cortex and swamps. Critical to this hypothesis, however, a periderm composed ofelongate, radially ar­ are assumptions concerning positional vari­ ranged, thick-walled cells. Unlike the New Al­ ability in wood anatomy and potential irreg­ bany Shale specimens, however, "secretory ularities in the relationship between wood cells" typically occur in the European axes at anatomy and edaphic conditions. the boundary of the cortex and periderm. Valid comparison of secondary xylem fea­ Moreover, leaf bases are preserved in the Eu­ tures between plants can be made only if the ropean stems, allowing for a reasonably con­ respective axis fragments are from equivalent fident assignment ofthe material to established parts ofthe plant (e.g., base ofstem, distal twig, genera. Because information pertaining to the etc.) (Bailey and Faull, 1934). Recognizing po­ occurrence and morphology ofleafbases in the sitional equivalency in fossillepidodendralean New Albany Shale axes is presently lacking, stems is not a significant problem, at least in we hesitate to assign the stems to a particular theory, because of the documented relation­ lepidodendralean genus. Although the impor­ ship that exists between axis morphology and tance of leaf base morphology in generic de­ position (Walton, 1935; Eggert, 1961; Meyer­ limitation within the Lepidodendrales has re­ Berthaud, 1984). Stems with small, nonparen­ cently been downplayed (DiMichele, 1983), and chymatous protosteles and large quantities of thus such reluctance may seem unwarranted, secondary xylem (i.e., total xylem radius/pri­ we cannot be certain that the stems were char­ mary xylem radius >- 1.0) represent basal parts acterized by persistent leaf cushions since the of the trunk. The secondary xylem cylinder surface has been completely abraded. This cau­ decreases in thickness acropetally, and the pri­ tious approach is further justified in view of mary xylem becomes parenchymatized and in­ the fact that the specimens, as possibly the creases in width (i.e., total xylem radius/pri­ oldest anatomically preserved lepidodendra­ mary xylem radius decreases). At still higher lean stems currently known, may not corre­ levels in the axis, the primary xylem and sec­ spond to generalizations based on analysis of ondary xylem cylinders become narrower, and 1756 AMERICAN JOURNAL OF BOTANY [Vol. 74 the pith tapers. Specimens with nonparenchy­ that in seed plants (Cichan, 1985), and it is matous protosteles, small amounts ofprimary unlikely that members of these two divergent xylem, and no secondary xylem (i.e., total xy­ groups responded to environmental variations lem radius/primary xylem radius = 1.0) cor­ in a similar manner. Clearly, the suggestion of respond to distal branches. The New Albany a relatively dry environment, being based sole­ Shale specimens described in this study exhibit lyon the analysis of a single element of the a relatively thick cylinder of secondary xylem flora, is preliminary, and continued study of (radius = 3.6 mm) and a narrow (radius = 0.6 New Albany Shale plants is needed to refine mm) protostele and therefore probably rep­ (or negate) the hypothesis. Nevertheless, the resent near-basal portions of the stem. If the work illustrates the potential value ofecophy­ width of secondary xylem tracheids in lepi­ letic analysis of wood anatomy in evaluating dodendralean axes decreases acropetally with­ the environmental characteristics ofsource re­ in the plant, as assumed by Cichan (1986), then gions in the study of fossil floras. the elements in the axis fragments described in this study are likely to be amongthe broadest LITERATURE CITED for the entire plant. Thus, secondary xylem ANDREWS, H. N., C. B. READ, AND S. MAMAY. 1971. A tracheids in the New Albany Shale axes are Devonian lycopod stem with well-preserved cortical likely to have been substantially narrower than tissues. Palaeontology 14: 1-9. those in coal swamp lepidodendraleans re­ ARNOLD, C. A. 1940. Lepidodendron johnsonii, sp. nov., gardless of the position of the sampled coal from the Lower Pennsylvanian of central Colorado. swamp stem fragments within their respective Contrib. Mus. Paleont. Univ. Mich. 6: 21-52. BAILEY, I. W., AND A. F. FAULL. 1934. The cambium axis systems. and its derivative tissues. IX. Structural variability in Analysis ofliving groups has shown that the the redwood Sequoia sempervirens, and its signifi­ relationship between wood anatomy and cance in the identification of the fossil woods. 1. Ar­ edaphic conditions is not universally consis­ nold Arbor. IS: 233-254. tent in that plants with wood exhibiting me­ BANKS, H. P. 1944. A new Devonian lycopod genus from somorphic features may occur in xeric habitats southeastern New York. Amer. J. Bot. 31: 649-659. CAl, C. Y., AND H. Z. QIN. 1986. First discovery of a (Rury and Dickison, 1984; Rury, 1985). It has stem with internal structure, referable to Lepto­ been noted, however, that the leaves in these phloeum rhombicum Dawson from the Upper De­ plants are typically characterized by a set of vonian ofXinjiang. Acta Palaeontol. Sinica 25: 516­ xeromorphic features and, thus, probably act 524. to buffer the wood from the effects of water CARLQUIST, S. 1977. Ecological factors in wood evolu- tion: a floristic approach. Amer. J. Bot. 64: 887-896. stress. The secondary xylem in the Mississip­ CHITALEY, S. 1982. Preliminary report on some plants pian lycopsid stem described herein appears to from the Cleveland shale. Kirtlandia 38: 91-104. be characterized by features that are xero­ CICHAN, M. A. 1985. Vascular cambium and wood de­ morphic relative to those in other woody ly­ velopment in Carboniferous plants. I. Lepidoden­ copsids. As far as is currently known, wood drales. Amer. J. Bot. 72: 1163-1176. with xeromorphic features (as judged by com­ --. 1986. Conductance in the wood ofselected Car­ boniferous plants. Paleobiology 12: 302-310. parison between plants within the same lin­ DIMICHELE, W. A. 1983. Lepidodendron hickii and ge­ eage) does not occur in plants growing in mesic neric delimitation in Carboniferous lepidodendrid ly­ conditions. Thus, the suggestion that the woody copods. Syst, Bot. 8: 317-333. lycopsid from the New Albany Shale grew in --, AND T. L. PHILLIPS. 1985. Arborescent lycopod a relatively dry environment appears to be val­ reproduction and paleoecology in a coal-swamp en­ id insofar as the relationship between wood vironment oflate Middle Pennsylvanian age. (Herrin Coal, Illinois). Rev. Palaeobot. Palynol. 44: 1-26. anatomy and environment is currently under­ EGGERT, D. A. 1961. The ontogeny of Carboniferous stood. arborescent Lycopsida. Palaeontographica 108B: 43­ At present, virtually nothing is known about 92. the environment of the source region of the FELIX, C. J. 1952. A study of the arborescent lycopods New Albany Shale flora. Based on the evidence ofsoutheastern Kansas. Ann. Missouri Bot. Gard. 39: from wood anatomy, it is proposed that the 263-288. GORDON, W. T. 1908. On Lepidophloios Scottii (a new woody lycopsid described herein grew in an species from the Calciferous Sandstone series at Pet­ environment that was substantially drier than tycur, Fife). Trans. R. Soc. Edinburgh 46: 443-453. thatoftheCarboniferouscoal swampsand may GRIERSON, J. D., AND H. P. BANKS. 1963. Lycopods of have been subjected to occasional periods of the Devonian of New York state. Paleontographica waterstress. It should be noted that the absence Americana 31: 220-290. of growth rings in the wood is of little signif­ JENNINGS, J. R. 1972. A new lycopod genus from the Salem limestone (Mississippian) of Illinois. Palae­ icance in this interpretation. The pattern of ontographica 137B: 72-84. cambial activity in lepidodendralean axes ap­ KISCH, M. H. 1913. The physiological anatomy of the pears to havebeen fundamentally different from periderm of fossil lycopods. Ann. Bot. 27: 281-320. November 1987] CICHAN AND BECK- MISSISSIPPIAN LYCOPSID 1757

MEYER-BERTHAUD, B. 1984. Les axes de lycophytes a tribution ofanatomicallypreserved floras in the Lower structure anatomique conservee du Carbonifere basal Carboniferousin western Europe. Trans. R. Soc. Edin­ (Tournaisien) de la Montagne Noire: Trabicaulis gen. burgh 75: 311-340. nov. et Landeyrodendrongen. nov. Palaeontographica SEWARD, A. c., AND A. W. HILL. 1900. On the structure 190B: 1-36. and affinities ofa lepidodendroid stem from the Cal­ PANNELL, E. 1942. Contributions to our knowledge of ciferous Sandstone of Dalmeny, Scotland, possibly American Carboniferous floras. IV. A new species of identical with Lepidophloios Harcourtii (Witham). Lepidodendron. Ann. Missouri Bot. Gard. 29: 245­ Trans. R. Soc. Edinburgh 39: 907-931. 274. SMITH, D. L. 1962. The stems of three species of lepi­ PHILLIPS, T. L. 1979. Reproduction of heterosporous dodendrid from the Scottish Lower Carboniferous. arborescent lycopods in' the Mississippian-Pennsyl­ Ann. Bot. 26: 533-550. vanian of Euramerica. Rev. Palaeobot. Palynol. 27: STEIN, W. E., D. C. WIGHT, AND C. B. BECK. 1982. Tech­ 239-289. niques for preparation of pyrite and limonite per­ PIGG, K. B., AND G. W. ROTHWELL. 1983. Chaloneria mineralizations. Rev. Palaeobot. Palynol. 36: 185­ gen. nov.; heterosporous lycophytes from the Penn­ 194. sylvanian ofNorth America. Bot. Gaz. 144: 132-147. STEWART, W. N. 1983. Paleobotany and the evolution READ, C. B. 1936. A Devonian flora from Kentucky. J. of plants. Cambridge University Press, New York. Paleontology 10: 215-227. THOMAS, B. A. 1978. Carboniferous Lepidodendraceae ---, AND G. CAMPBELL. 1939. Preliminary account and Lepidocarpaceae. Bot. Rev. 44: 321-364. ofthe New Albany Shale flora. Amer. MidI. Naturalist ---. 1981. Structural adaptations shown by the Lep­ 21: 435-453. idocarpaceae. Rev. Palaeobot. Palynol. 32: 377-388. RURY, P. M. 1985. Systematic and ecological wood anat­ WALTON, J. 1935. Scottish Lower Carboniferous plants: omy ofthe Erythroxylaceae. lAWA Bull., n.s. 6: 365­ the fossil hollow trees of Arran and their branches 397. (Lepidophloios wunschianus Carruthers). Trans. R. Soc. ---, AND W. C. DICKISON. 1984. Structural correla­ Edinburgh 58: 313-337. tions amongwood, leaves and planthabit. In R. White WILLIAMSON, W. C. 1872. On the organization of the and W. C. Dickison [eds.), Contemporary problems fossil plants of the Coal Measures.-Part III. Lyco­ in plant anatomy. Academic Press, New York. podiaceae (continued). Phil os. Trans. R. Soc. London SCOTT, A. C; J. GALTIER, AND G. CLAYTON. 1984. Dis- 162: 283-318.