Taxodioxylon Hartig, 1848 emend. Gothan, 1905

Iamandei, Stănilă & Iamandei, Eugenia, 2017, New Trees Identified In The Petrified Forest Of Middle Miocene From Zarand, Apuseni Mountains, Romania., Acta Palaeontologica Romaniae 13 (2), pp. 37-90 : 47-58

Genus Taxodioxylon Hartig, 1848 emend. Gothan, 1905 Taxodioxylon taxodii Gothan, 1906

Fig. 7 , photos a-i.

Material

The studied material was collected from Prăvăleni-Ociu area like this: one sample of petrified wood was collected from Ociu area, from MarinaȘu valley, six samples also from Ociu on the Church brook, and one sample from Prăvăleni, BodiȘteanu brook from Mid-Miocene volcano-sedimentary deposits (Late Badenian-Early Sarmatian), all having beige to ash-brown color and centimetric size. It represents silicified wood and display a regular fibrous texture, and annual rings suggesting a conifer. Some fragments remained after oriented slides cut, are kept now in GIR collection at National Geological Museum - Bucharest under the inventory number: 26,383; 26,406; 26,409; 26,475; 26,417; 26,418; 26,442 and respectively 26,415 (i.e. 110; 250; 291; 440; 492; 494; 731 and 449 as field numbers).

Microscopic description

Growth rings distinct, variably sized, of 10-44 tracheids with gradual transition from early to late wood, with ring boundary marked by 2-5-7 tangential rows of thick walled cells of late wood. Normal axial resin ducts are absent, but sometimes, resiniferous tissue appears, probably of traumatic origin.

The tracheids polygonal rounded in cross section (4-5 sides) usually larger in the early wood. Between two successive rays there are 1-11(16) regular radial rows, sometimes with larger ones intermingled. When solitary the tracheids have rounded polygonal section frequently determining intercelular spaces, and have radial / tangential diameters of 16-50(63)/(16)20-48 μm, smaller in the late wood: 8-12/8-12-24 μm r/tg diameters. The wall thickness is 2-5 μm double walls, thicker in the late wood: 8- 10(12) μm. The density of the structure is of 900-1850 tracheids on mm 2. On the tangential walls the pitting is missing or if sometimes it appear is either uniseriate, spaced, or as pairs irregularly arranged. The rounds to oval pits have 8-10 μm with round to elliptic apertures of 1.5-3 μm. The radial pitting is uniseriate or biseriate, pits of abietinean type, opposite, spaced or contiguous arranged, with round borders of 12-19 μm in diameter and with round apertures of 3-5 μm. Sometimes obvious crassulae are present, sometimes are missing. The tracheidal walls have oblique striations and inside lumina resin globules sometimes appear.

The axial parenchyma in cross section appears relatively frequent, sometimes even abundant in the transitional wood, diffuse or in discontinuous tangential lines of rounded cells smaller than the tracheids or similarly sized. Vertically presents thin walls of 1-1.5 μm (simple wall), smooth and sometimes slightly constricted at the horizontal (end) walls which appear rugose of 1.5-2 μm or clearly nodular, with up to 8 bead-like knots, with 1-4 very obvious denticles. Inside parenchyma cells resin content of reddish-brown color appear as big and small globules, or granular, or as remains or as plugs or compact with convexe empty spaces. Sometimes in the cross-fields with the ray cells display up to 4 simple pits in two superposed rows.

Medullary rays in cross section appear linear and in the tangential sections display the uniseriate aspect often with 1-7 biseriate storeys or even as biseriate rays, of 1-16 up to 53 cells or more. The ray cells are polygonal-rounded to round or vertical oval, of 12-18-24 μm in diameter, with lateral intercellular triangular spaces not always very obvious. As frequency, there are 6-12 rays on tangential millimeter. Radially the rays show homocellular structure, with cells all procumbent of 16-20(24) μm high, the marginals taller: 20-24(32) μm. The horizontal walls are smooth and have 3-4(6) μm the double wall. The tangential walls are thin and smooth or slightly rugose straight and inclined or arcuated. Indentures indistinct or even are absent. The typical taxodioid cross fields have 1-3(4) taxodioid pits, oval to round, of 7-9 μm, with large- elliptic apertures, inclined to horizontal, of 2-4 μm. They are arranged in 1-2 horizontal rows or diagonal or triangular, sometimes badly preserved or covered by traces of resin globules giving an aspect of false unilaterally composed pits. In the taller marginal fields, pitting appears as vertical pairs or as up to 6 on two superposed rows. Sometimes cross-fields with parenchyma can be seen, with up to 4 simple pits in two superposed pairs.

Affinities and discussions

The xylotomic description of all the studied specimens allowed the outlining of a characters combination similar to those of the taxodiaceous Cupressaceae , namely: shape and distribution of the tracheids and of the parenchyma in cross section, the tracheidal pitting on the tangential and on the radial walls, the typical taxodioid type of the cross fields and the arrangement of the taxodioid pits.

The comparison with the extant and fossil described taxodiaecous genera allowed us to establish the most affinities with Taxodium Rich. and respectively with Taxodioxylon (Hartig) Gothan, 1906 , taking into account the obvious presence of the end (horizontal) walls of parenchyma, with up to 8 knots, or even denticles.

From the species of Taxodioxylon already described our specimens mostly reassembles with Taxodioxylon taxodii Gothan 1906 as is described by many authors (see Greguss, 1967; Gottwald 1992; Selmeier, 2001), a fossil species equivalent to the extant species Taxodium distichum ( L.) Rich., a tree living today in restricted areas in South USA, Mexico and Guatemala, within riparian and wet habitats ( Earle, 2017), in which xylotomically is remarkable that the radial pitting of the tracheids, the nodular end wall of parenchyma and the typical aspect of the cross-rings are very similar. Also we have described Taxodioxylon specimens from Romania (Iamandei et al., 2005a; 2008c).

After this discussion on the affinities of our studied material we decided to assign all the 8 studied specimens to the species Taxodioxylon taxodii Gothan, 1906 .

Subfamilia Sequoioideae (Luerss.) Quinn, 1989 (see

Gadek et al., 2000)

(former Family Taxodiaceae Warming , nom. cons.) Genul Sequoioxylon Torrey, 1923 , emended

Sequoioxylon gypsaceum (Goeppert) Greguss, 1967

Fig. 8 , photos a-i

Material The studied material represented by 48 samples of petrified wood were collected from Prăvăleni- Ociu areas, hosted now in GIR collection in the repository of the National Geological Museum - Bucharest under next specified inventory numbers (followed by the field numbers for a better identification). All the material represents silicified wood and usually displays a regular fibrous texture, and annual rings suggesting a conifer and is hosted like this: x 8 samples of petrified wood were collected from

Basarabasa hill, and are deposited in collection under the next inventory numbers: 26,460;

26,461; 26,462; 26,463; 26,464; 26,466; 26,467

and 26,468 (the field numbers: 807; 809; 810;

812; 813; 821; 823 and 824, respectively); x 1 sample of petrified wood was collected from

Prăvăleni area on BodiȘteanu valley, and is deposited in collection under the next inventory number: 26364 (field number: P 22); x 5 samples were collected from Prăvăleni area on the Cremenea hill, and are deposited in collection under the next inventory numbers: 26,397;

26,398; 26,410; 26,411 and 26,412 (the field numbers: 176; 180; 371; 336* and 376*, respectively); x 3 samples of petrified wood were collected from

Hoarna Tarnița valley, and are deposited in collection under the next inventory numbers:

26,389; 26,394 and 26,401 (the field numbers:

115; 117 and 206*, respectively); x 10 samples of petrified wood were collected from MarinaȘu valley, south of Ociu village and are deposited in collection under the inventory numbers: 26,420; 26,421; 26,422; 26,424;

26,471; 26,348; 26,449; 26,450; 26,451 and

26,452 (the field numbers 570; 576; 583; 587;

600; 601*; 781; 783*; 786 and 787, respectively);

x 7 samples of petrified wood were collected from inside Ociu village, on the dirty roads and are deposited in collection under the inventory numbers: 26,386; 26,387; 26,698; 26,448; 26,349; 26,453 and 26,458 (the field numbers 113b; 113c; 113d; 747; 757; 794 and 804, respectively);

x 8 samples of petrified wood were collected from inside Ociu village, on the Church Brook, and are numbered with the inventory numbers: 26,407; 26,472; 26,474; 26,476; 26,427; 26,428; 26,430 and 26,443 (the field numbers 263; 602; 607; 651; 653; 654; 664 and 732, respectively);

x 6 samples of petrified wood were collected from the brook valley from north of Ociu village, and are numbered with the inventory numbers:

26,431; 26,433; 26,434; 26,435; 26,436 and 26,437 (the field numbers 669; 677; 691; 692; 700 and 701, respectively).

Previously (Iamandei et al., 2000) other nine specimens were already described and published also as Sequoioxylon gypsaceum (Goeppert) Greguss, 1967 . And also all that material was collected from same area as the material studied for the present paper from the same Mid-Miocene volcano-sedimentary deposits (Late Badenian-Early Sarmatian), and is kept now in GIR collection in the repository of the National Geological Museum - Bucharest un- der next specified inventory numbers: 26,341 -26,349 (field numbers: 32; 39; 136; 161; 169, 374; 375; 602 and 757, for a better identification) .

Microscopic description

The growth rings present, distinct, marked by 1-5(13) rows of small cells, often flattened and thick to very thick walled of late wood contrasting with the early wood which is constituted from larger lumina and have thin walls. Usually wide the annual rings are unequal in size having (1)3-18-39(65) cells, with gradual transition from early to late wood. Normal axial resin ducts are absent, but sometimes some with traumatic character appear, even as traumatic tissue - groups of tracheids or parenchyma - invaded by resin, which is visible in all sections.

The tracheids are rectangular or polygonal with 5-6 sides and sometimes, in the early wood, variably sized cells appear, rounded, deformed by compression, seeming to be intermingled or even indented with them. Their lumina have the radial / tangential diameters of 20-70(80) / 30- 60(70) μm or more. The wall thickness is of (3.5)5-8(10) μm double wall in the early and transitional wood and in the late wood has of 12-15 μm double wall, sometimes up to 28 μm when the lumina appear point like or slit-like. Between two successive succesive rays 1-13 regular radial rows of tracheids appear, and their frequency is of 425- 1496 tracheids on mm 2. The tangential wall are usually unpited and are smooth or slightly verrucose and without spiral thickenings. However sometimes on some tracheids were seen small pits of 6-9 μm border diameter and 3-4 μm, sparsely arranged on 1-2 vertical rows. Radial pitting of abietinean type with bordered pits slightly ornamented, of (12)16-19 μm in diameters with apertures of 4-5 μm, smaller in the late wood, spaced or contiguous arranged in 1-3 vertical rows rarely 4. Sometimes the opposite pits touch each other after a vertical line. Sometimes irregularities in the triseriate pitting appear as storeys of 4 crowded pits or in the uniseriate rows where appear opposite pairs of pits or small portions with biseriate alternate pits. Crassulae are very obvious, even if on some tracheids are missing. The structures are often badly preserved but it is clear that spiral thickenings are absent.

The axial parenchyma appear rather abundant in cross section, diffuse, dispersed among the tracheids of the early wood or in the terminal wood as slightly irregular short tangential lines of 2-3(5) cells, usually slightly crushed and with dark content. Vertically it appear as rectangular thin walled cells sometimes simple pitted and in radial view as weak constriction at the horizontal (end) walls which are thin (1-3 μm), smooth, slightly rugose or weakly nodular (1-3 small knots), and indistinct simple pitted. The resin content appears as big globules or dark remains, or plugs, or compact, without filling the entire cell.

The medullary rays in cross section are relatively linear and are formed from rectangular elongate cells sometimes crushed, with small simple pits, irregularly arranged on the horizontal wall. In the tangential sections the rays appear usually uniseriate, of 1-20(32) cells high or more with local biseriation, sometimes up to 5 successive biseriate storeys, tending to an already biseriate aspect. The ray cells are usually polygonal rounded or oval of 12-16- 20 μm, rarely cribrate by simple piting. Often lateral intercellular spaces are present. The ray-density is 3-6-10 rays on tangential millimeter. Radially the rays are homocellular with cells all procumbent of 14-18 μm high, the marginals taller: 20-40 μm. The horizontal walls are relatively thin, of 2-6 μm the double wall, smooth and simple pitted and the marginals with slightly waved outer wall. The tangential walls are vertical or slightly arcuated and thin (1-2 μm), smooth or slightly rugose, rarely with few knots. Indentures absent. The cross fields have usually small pits, usually of taxodioid type or even ooporoid, of 6-9 μm in diameter, with rounded to oval borders, 1-3(4) pits in horizontal row, the pairs slightly diagonal and with oblic to horizontal elliptic small apertures, or as oblic slits to vertical in the late wood. The marginal cross fields have (1)2-6 similar pits, on two slightly irregular rows. Often the ray cells have resin content. In cross fields with axial parenchyma cells sometimes appear simple pits as 2 superposed pairs.

Affinities and discussions

The synthetic xylotomical description of a numerous population of similar samples revealed details that send to Cupressaceae – of "taxodiaceous" type, but from Sequoioideae Subfamily (see Farjon, 2005; 2010), by the presence of radial pitting up to triseriate opposite and with obvious crassulae, the usually thin and smooth end (horizontal) wall of the parenchyma rarely rugose or with few knots and the typical cross field with taxodioid to slightly ooporoid pits ( Greguss, 1955; 1967).

Some resemblances of our specimens with fossil forms already described by Greguss (1967), probably erroneously identified with Metasequoioxylon genus, considered equivalent to the extant Metasequoia glyptostroboides Hu & Cheng , a tree described in China in 1943 (see Greguss, 1955; Earle, 2017).

Otherwise most of the described characters are frequently met in other "taxodiaceous" woods also. The comparison with Schönfeld's species Taxodioxylon metasequoianum Schönfeld, 1955 , wrongly renamed by Greguss (1957, 1967) as Sequoioxylon or Metasequoioxylon germanicum , and with M. hungaricum Greguss, 1967 is unsatisfying (see whole discussion in Philippe et al. 1999, p.671), since our material have not pitted parenchyma cells and the cross field pitting is different. Also, Metasequoia milleri Rotwell et Basinger, 1979 described from Allenby Formation (Middle Eocene) from British Columbia, Canada as is quoted by Basinger (1981), show differences in the height of rays and pitting in cross fields. Moreover, according to many palaeobotanists (Petrescu, 1999, written communication), referring to foliar imprint data, Metasequoia was probably absent from the flora of the European territory.

The comparison with the structure of other described "taxodiaceous woods" still shows the greatest similarities with the genus Sequoioxylon Torrey and partially with the genus Taxodioxylon (Hartig) Gothan, 1905 and thus the separation of the two genera is still problematic. Kräusel (1949) has ruled the comprehensive form-genus Taxodioxylon but this didn't solved the problem of differentiating the several types of "taxodiaceous" woods. However, there are palaeoxylologists that still contest the validity of the genus S equoioxylon Torrey, considering that the diagnosis of the Taxodioxylon genus is sufficiently comprehensive and that the establishment of new areas of competence of the two genera is likely to complicate the determination of fossil wood (Privé-Gill, 1977).

Greguss (1967) considered that the name Taxodioxylon should remain reserved for structures characterized by the presence of numerous nodular thickening in the horizontal (end) walls of the axial parenchyma, typical of the extant Taxodium genus. Although the aspect of axial parenchyma seems extremely variable in the current genus Sequoia (Privé-Gill, 1977) , it should be recalled that in the "taxodiaceous" fossil woods still comprise the genera Glyptostroxylon Conwentz, 1884 and Metasequoioxylon Greguss, 1967 as equivalents of Glyptostrobus and Metasequoia , respectively.

Selmeier (2001) described a Taxodioxylon sp. from Czech Rep. and added a pertinent note: " Taxodioxylon is found throughout the whole Tertiary and is one of the most common Tertiary coniferous woods in Europe and the rest of the Northern Hemisphere. Most of the Tertiary (not Upper Cretaceous) wood remains are to be assigned to T. gypsaceum which is a highly variable polyphyletic species that, according to the standard literature the cross-field pits vary from taxodioid to glyptostroboid or cupressoid" (Selmeier, 2001).

More recently, Teodoridis & Sakala (2008) describing a Taxodioxylon gypsaceum from Czech confirm the equivalence with the wood of modern Sequoia , quoting Privé-Gill (1977) and Dolezych & Schneider (2006) but send, they say, also to an extinct form Quasisequoia couttsiae (Heer) Kunzmann,1999 . This species was described by van der Burgh & Meijer (1996) from the Late Eocene of Schleenhain, Germany, in a coal layer with the wood of T. gypsaceum and leaves and cones belonging exclusively to Q. couttsiae . More than this, ignoring the valid genus Sequoioxylon Torrey, 1923 , there is a proposal for a doubtful new genus, Quasisequoioxylon, which would be intermediate between Cupressinoxylon Goeppert characterized by cupressoid cross-field pits and Taxodioxylon with 2-3 taxodioid cross-field pits on radial tracheidal walls ( Dolezych 2005: 256, published PhD Thesis).

Otherwise, even the taxonomy of the extant " Taxodiaceae " was changed after advanced and modern studies, being included in Cupressaceae family as subfamilies: Cunninghamioideae , Taiwanioideae , Athrotaxidoideae, Sequoioideae , Taxodioideae ( Farjon, 2005, 2010; Earle, 2017). It is clear that as belonging to different subfamilies, Sequoia and Taxodium and their fossil correspondent Sequoioxylon and Taxodioxylon both of them valid taxa, must define different entities.

Also there are new palaeoxylologists from Russia, Canada, Ukraine, Turkey who have admitted the validity of the genus and even have described new species under Sequoioxylon genus (see: Blokhina, 1986; 1997; 2004; Blokhina et al., 2000; 2010; Afonin, 2013; YiTiemei et al., 2013; Ozgenc, 2018).

So, after this discussion we believe that the use of the valid genus name Sequoioxylon Torrey, 1923 is justified, especially since the description of a fossil taxon would have to require the systematic reference to the extant genera or species, if possible. We admit, according to ICBN recommendations, that the presence of traumatic structures has no taxonomic value, but such structures have frequently been encountered in specimens studied by us, and probably they have an environmental significance. It is appropriate in these circumstances to redefine the genus diagnosis of Sequoioxylon , originally described by Torrey (1923), specifying that all structures reported to the Sequoia type wood, generally described as Taxodioxylon , it is appropriate to be assigned to the genus here emended:

Genus Sequoioxylon Torrey, 1923 emended diagnosis: Distinct growth rings, with gradual transition of early to late wood. Regular resin ducts absent. Round to polygonal tracheids of varying size, of 60-80(-100) μm in diameters, thin-walled, of 3-5μm double wall, density 425- 1496 tracheids / mm 2. Tangentially the tracheids have smaller and fewer pitting, radially larger, abietineous, bordered pits of 16-19 μm in diameter, spaced or contiguous, opposite, on 1-3 vertical rows, usually with obvious crassulae, walls without spiral thickening. Parenchyma abundant, diffuse or as short tangential lines; horizontal end walls (of 1-3 μm), smooth, slightly rugose or weak nodular, with 1 (2) small nodules; resin content as large globules or dark remains, as a plugs or compact, but without filling the whole cell. Rays with pitted horizontal walls, uniseriate, rarely biseriate, high to very high, with round to elliptical cells determining intercellular lateral spaces; density - of 3-10 rays on tangential millimeter, homogeneous and homocellular with all procumbent cells of 20 μm tall, marginals higher up to 40 μm, with the horizontal walls thin, smooth and simple, tangential walls vertical or arcuate, thin and smooth (1-2 μm), rarely nodular, without indentures, outer wall of marginals slightly wavy; the cross fields have typical pitting of small taxodioid pits, 1-3 in horizontal or diagonal pairs; the marginal cross fields have 2-6 pits on two rows.

The comparison of our specimens with Sequoioxylon cf. germanicum Greguss, 1967 was unsatisfactory but it suggested similitudes with the other forms of S. gypsaceum described by Greguss (1967), in which the growth rings are distinct, even if not always, the resinous parenchyma has a tendency to appear terminally, the thin-walled variably-sized tracheids reaching sometimes 100 μm in diameter, without spiral thickenings but with spaced pitting in 1-2-3 rows on both the walls and distinct crassulae, the rays of 2-18 cells in height, ray-cells with diameter of 13- 15-20 μm. Also the parenchyma has end (horizontal) smooth walls, sometimes simple pitting on vertical walls and granular content, the cross-fields ray-tracheid have 3- 5 taxodioid pits arranged on 1-2 horizontal rows, and sometimes transverse tracheids are present, details most similar with the extant species Sequoia sempervirens L.

Among the described forms of Greguss, our studied structures mostly resemble to Sequoioxylon gypsaceum no. 1 (Goepp.) Greguss, 1967. The same species described by Petrescu & Dragastan (1971) from the Oligocene at SuslăneȘti, is also xylotomically very close to our specimens.

Also, the species of Taxodioxylon described by Gottwald (1992) from the Eocene of Helmstedt, Germany, have some xylotomic details very similar to our specimens, although not always identical. It also must be reattributed to Sequoioxylon genus.

The here studied numerous specimens have sometimes traumatic resin ducts or traumatic tissue, with relatively abundant parenchyma, diffuse or short tangential lines, with 1-3 rows or bordered pits and obvious crassulae on the radial walls of the tracheids, with uniseriate rays, frequently with short biseriate storeys, ray cells with thin and smooth walls, the tangential ones slightly nodular, cross fields with 1-3 taxodioid pits in the ray body fields and 3-6 or more in the marginal fields, with axial parenchyma having resinous content as compact or granular masses or as round or oval globules, and the horizontal (end) walls smooth or rarely slightly nodular with 1(3) knots, allow us to assert that we are in front of a fossil of Sequoia , very similar to the structure of the species Sequoioxylon gypsaceum (Goepp.) Greguss, 1967 .

This species is identical as description with Taxodioxylon gypsaceum (Goepp.) Kräusel, 1949 , that after Privé-Gill (1977) has fairly diverse forms and has the extant correspondent in Sequoia sempervirens Endl. and was widely spread in the northern hemisphere (Eurasia and North America) during the Tertiary.

However the Sequoioxylon genus was created by Torrey (1923) on the basis of a traumatic wood (with secretory cysts). Greguss (1967) proposed the use of this genus for the structures that can be compared to the current Sequoia genus, characterized by the horizontal (end) walls of axial parenchyma perfectly smooth, rarely slightly thicker or rugose, or very weakly nodular, tracheidal radial pitting 1-3-seriate with obvious crassulae. The normal cross fields with 1-3 taxodioid or slightly podocarpoid or round pitting in horizontal row, lesser as vertical pairs, more numerous in marginal fields where they can appear on two horizontally, rarely alternating or slightly irregular rows. Studying numerous specimens Greguss (1967) attributed to this genus the species: gypsaceum , medullare, podocarpoides and germanicum , and many forms determined only generically, on a badly preserved material.

Roy & Stewart (1971) accepted this proposal as justifiable and have described Sequoioxylon gypsaceum from Cypress Hills Formation, Saskatchewan, Canada (Oligocene), however returning to the form of Taxodioxylon gypsaceum after some years (Ramanujam & Stewart, 1969) in Edmonton Formation, Alberta, Canada (Late Cretaceous), for which we propose its renaming as Sequoioxylon gypsaceum .

The genus name was used also by Nagy (1969), Petrescu & Popa (1971), and Petrescu (1978) for similar structures described in the Oligocene from Northwest Transylvania, Romania with gypsaceum and giganteoides species, the last one revising the taxon described by Huard (1967) as equivalent to the extant species Sequoia gigantea Decaisne.

Other new species of Sequoioxylon described last years in the world as: S. chemrylicum Blokhina, 1997 ; S. canadense Blokhina et Nassichuk, 2000 ; S. sachalinicum Blokhina, 2004 , S. burejense Blokhina, Afonin et Kodrul, 2010 ; S. dimyense Afonin, 2013 , are quite similar with S. gypsaceum .

Otherwise, the species, Sequoioxylon gypsaceum , was described by us in the same area and in other Carpathian sites also ( Iamandei et al., 2000b; 2004b; 2008a; 2012).

As a result of all these discussions, we attribute all the 48 here studied specimens to the species Sequoioxylon gypsaceum (Goeppert) Greguss, 1967 .

Sequoioxylon multiseriatum Ramanujam et Stewart, 1969 nov. comb.

Fig. 9 , photos a-i.

Material

A sample of petrified wood was collected from Prăvăleni area, the Hoarna Tarnița brook, from Mid- Miocene volcano-sedimentary deposits (Late Badenian-Early Sarmatian), having whitish color with brown tents and centimetric size. It is silicified and displays a regular fibrous texture, and annual rings suggesting a conifer. Some fragments remained after oriented slides cut, are kept now in GIR collection at National Geological Museum - Bucharest under the inventory number 26359 (194 as field no.).

Microscopic description

Growth rings distinct, variably sized (of 4-20 cells) but usually are low, their boundary is marked by 2-5(7) rows of thick-walled cells of late wood. The early wood is usually partially crushed. Normal axial resin ducts are absent.

The tracheids in cross section are polygonal rounded, without intercellular spaces. Between two successive rays there are 1-3-16 radial regular rows of tracheids, slightly alternately arranged. Their lumina have radial / tangential diameters of 40-80 / 28-60 μm, smaller in the late wood: 4-8-20 / 20-28 μm. Their wall thickeness is of 6-8-11 μm double wall, thicker in the late wood: 12-16 μm double wall. The density is of 460-648 tracheids on mm 2. Tangential pitting is not distinct. Radially the bordered pitting of abietinean type, in 1-3 vertical rows, opposite, subopposite or slightly alternate, or even irregularly arranged, pits of 12-16-19 μm the diameter and with round apertures of 5-7 μm, and with crassulae. Sometimes brown flue resin content is present or as granular remains.

The axial parenchyma in cross section appear few, diffuse as round to elliptical cells smaller than the tracheids, and have relatively thin walls: 1-1.5 μm simple wall, but it appears abundantly in the longitudinal sections, when it shows weak constrictions at the end (horizontal) wall level. The horizontal end wall is smooth and thin, having less than 1 μm, sometimes weakly rugose. Inside cells appear resinous compact content or as globules, or plugs, or granular remains or sometimes no content but empty portions.

The medullary rays in cross section appear rectilinear usually uniseriate or even multiseriate more clear in the tangential section when often appear 2-3-4-seriate rays and with fusiform aspect, made up of unequal sized cells, and have (1)2-8-12-20(54) cells in height or more. The shape of the ray cells is round elliptical, with 12-20 μm in diameters and unpitted tangential walls. Ray density is of 3-5 rays / mm tangential. Radial they are homocellular, with cells all procumbent of 16-20 μm in height, the marginals taller, of 20-24 μm. The horizontal smooth walls have 4-4.5 μm double wall, the tangential walls are thinner, of 1-1.2 μm the simple wall are smooth, straight, vertical or inclined. The cross fields have 1-3(4) taxodioid pits to ooporoid, horizontally or diagonally arranged and similarly in the marginal fields. The pits have small round borders, or slightly oval of 5-6 μm in diameter, with round apertures of 1-1.2 μm.

Affinities and discussions

The studied specimen has xylotomic characters very similar to those of the classic "taxodiaceous" woods, represented by tracheids with large cross-section (up to 80 / 60μm the radial / tangential diameters), radial pitting 1-3- seriate, with crassulae, axial parenchyma with horizontal walls thin and smooth (sometimes weakly nodular), rays with up to 20 cells in height or more, having straight and smooth tangential walls and cross fields with 1-4 taxodioid to ooporoid pits, characters that could suggest the resemblance of our specimen with the current species of the Sequoia genus.

However there is a very special character, better observable in the tangential sections: there are uni- and multiseriate rays (of 2-3-4 cells thick), made up of polygonal ray-cells of slightly uneven sizes. The height of this kind of fusiform rays ranges from 10 to 54 cells, they have frequent intercellular lateral spaces, usually are clustered and among them uniseriate rays frequently appear.

The description corresponds perfectly to the diagnosis and the figures are quite identical to that of the Taxodioxylon multiseriatum Ramanujam et Stewart, 1969 , described on a fossil wood from the Maastrichtian of Edmonton, Alberta, Canada, a species found again by Ramanujam (1971) within the Late Cretaceous (Campanian, Oldman formation), in South Alberta. The authors point to the similarities with "taxodiaceous" structures, but especially with Sequoia wood type.

Following this critical analysis, we assigned our specimen to the species of Ramanujam & Stewart (1969) mentioned above, but since the predominant xylotomic characters indicate an almost perfect identity with Sequoioxylon , except for the presence of the multiseriate rays, which is a special character and we propose a new combination as name of the specimen studied by us: Sequoioxylon multiseriatum (Ramanujam et Stewart) nov. comb.

Angiosperms - Dicots

Order Saxifragales Dumortier

Family Altingiaceae Lindley, 1846

Genus Liquidambaroxylon Felix, 1884 Liquidambaroxylon speciosum Felix, 1884

Fig. 10 , photos a-i

Material

From a sample of petrified wood collected from Prăvăleni area, the right side of Hoarna Tarnița brook, to Cremenea Hill (field number 148) from Mid-Miocene volcano-sedimentary deposits (Late Badenian-Early Sarmatian). The sample come from a silicified trunk fragment and has beige-whitish color and centimetric size, and is kept now in GIR collection at National Geological Museum - Bucharest under the inventory number 26,296 (field number: 148). Under the magnifying glass fibrous structure, annual rings not very distinct, vessels and thick rays can be seen, typical for a dicotyledonate.

Microscopic description

The growth rings of this secondary wood in diffuse porous, with less distinct, marked boundaries by the flattened fibers of the late wood slightly and slightly dilation of the rays.

The vessels - are usually solitary and in short multiples of 2-3 pores, radial, tangential or oblique radii, or as irregular groups of 3-4 vessels, usually radially extended by 1-3 wider fibrotracheids. The solitary pores are polygonal, rounded or oval, are thick-walled of 4-6 μm simple wall or 8-9 μm double wall. The radial / tangential diameters for the solitary pores are 50-80 / 40-65 μm. The density is 88-100 pores per mm 2. The vessels have high scalariform perforations, with 10-14-16 fine bars, of 1-2 μm thick, relatively rare. The perforated plates are storied. The intervascular pits are bordered, oval opposite or horizontally elongated, to large scalariformes, of 11-16 μm long and 6.5 μm wide, and apertures of 8-11/1.5 μm. The vessels have numerous fine inclined spiral thickenings on the walls, not always very evident. The length of vascular elements is difficult to appreciate. Some vessels show large tyloses inside lumina.

The axial parenchyma - in cross section is apotracheally diffuse, few and paratracheal also few. In longitudinal view appears especially the paratracheal one, in vertical strands of 6-8-10 cells.

The medullary rays - in cross section seen consist of rectangular elongated cells, exhibit slight dilations at the boundaries of the growth rings, and have a relatively linear trajectory, sometimes touching vessels. Tangentially seen the rays are 1-2-3-seriate and have 14-25 cells in height. The ray cells have fairly thick walls (3.5-4 μm double wall), are round or slightly vertical oval, having 7- 10 µm in diameters. The uniseriate endings have 1-3 cells which bear inside shriveled gum remains. The frequency is of 7-10 rays per tangential millimeter. The rays are heterocellular, constituted of cells usually procumbent in the body, with 8-12 μm in height and square or upright, having 16-24 up to 48 μm in height in the 1-3 marginal cell rows are. Sometimes, oval to scalariform pits irregularly arranged, or in 2-3 horizontal rows, on the marginal fields in 4-5 horizontal rows in 1-2 groups. Sometimes, solitary crystals and black gums are visible.

The fibers - have polygonal cross sections, thick walls: 8 μm the double wall and relatively wide round lumina, and do not seem septated or pitted.

Affinities and discussions

The xylotomic characters presented by the studied here specimen are similar to those of representatives of the Altingiaceae Family (Watson & Dallwitz, 1992; Wheeler et al., 2010; APG IV, 2016) former Hamamelidaceae family (Metcalfe & Chalk, 1950; Greguss, 1959), a family that has today ca. 28 genera with 90 species, living in temperate to tropical areas, mostly subtropical.

As fossil taxa the family includes the Hamamelidoxylon Lignier with 4 species described by Lignier (1907), Grambast-Fessard (1969), Greguss (1969) and van der Burgh (1973), from France, Hungary and the Netherlands, and Liquidambaroxylon created by Felix (1884), and a series of species and specimens were described later in Hungary, Romania, Germany by Greguss (1967, 1969), Nagy & Petrescu (1969), and van der Burgh (1973 respectively.

Here is the original diagnosis of the genus Liquidambaroxylon Felix, 1884 , which has L. speciosum as type species: not too large but extremely numerous vessels, regularly distributed in narrower rings, with obvious decrease in size and number in the late wood, with scalariform perforations, thick-walled fibers, among them sporadically parenchyma and tracheids appear and large, heterogeneous rays, 1-3 seriate.

Thus, our specimen which exhibits fairly indistinct growth rings boundaries, solitary small vessels of 40-80 μm or in short radial multiples (in Hamamelidoxylon there are solitary or in pairs) and are very small (below 50 μm diameter). The vessels have storied scalariforms perforations, with 10-16 bars ( Hamamelidoxylon has usually higher ones, over 20 bars), bordered pitting to scalariform and spiral thickenings on vessels, rays 1- 3-seriate, heterogeneous, consisting of cells with fairly thick walled, with 1-3 tall marginal cells, thick-walled fibers, fibrotracheids and few parenchyma.

Comparing the xylotomic characters of our specimen with those of some already described species of Liquidambaroxylon ( Table 1), excluding Liquidambaroxylon kraeuseli Greguss, 1969 which was redescribed as Magnolioxylon by van der Burgh (1973) we have seen that there is a great resemblance with our specimen with those of the species

Liquidambaroxylon speciosum Felix as described by Felix (1884), Greguss (1967, 1969), Nagy & Petrescu (1969) and van der Burgh (1973).

In view of the presence of the specific characters and their variation shown by the described fossil forms and attributed to the quoted species, which could be the fossil equivalent of the extant species Liquidambar styraciflua L., known as American Sweetgum living today in eastern North America and also eastern Mexico to Honduras, but most probably of L. orientalis L., known as Oriental Sweetgum or Turkish Sweetgum living today in the southwest Turkey, Greece, Rhodes and we believe that it is not wrong we attribute the studied specimen to this form species which, apparently, has dominated the European Tertiary. Therefore, the studied specimen is a Liquidambaroxylon speciosum Felix, 1884 .

Figures

Fig. 7 Taxodioxylon taxodii Gothan, 1906. a - cross section: distinct growth-ring boundary - x50; b, c - cross-section: distinct growth boundary thick-walled tracheids in late wood, dispersed parenchyma - x100; d - tangential section: tracheids few pitted, parenchyma with resin content - x200; e, f - tangential section: tracheids few spaced pitted, parenchyma with resin content (e) and end horizontal denticulate walls (f) - x200; g-i - radial section: radial pitting on tracheids, cross-fields with 2-4 pits on two storeys - x200.

Fig. 8 Sequoioxylon gypsaceum (Goeppert) Greguss, 1967. a - cross-section: less distinct growth-ring boundary, parenchyma disperse - x50; b, c - cross-section: thin-walled polygonal tracheids, dispersed parenchyma - x100; d-f - tangential section: - unpitted tracheids, parenchyma with globular resin content and smooth and thin horizontal end walls, uniseriate high rays, or with biseriate storeys or even biseriate - x200; g-i - radial section: radial pitting on tracheids, typical cross-fields with 1-6 taxodioid pits on 1-2 storeys, sometimes alternate - x200.

Fig. 9 Sequoioxylon multiseriatum (Ramanujam et Stewart) nov. comb. a-c - cross section: less distinct growth-ring boundary, few parenchyma disperse - x100; d - tangential section: uniseriate rays – x100?; e, f - tangential section: - broad rays 2-5-seriate, dispersed parenchyma - x100; g - tangential section: multiseriate rays, parenchyma with thin end wall with a single knot – x200; h-i - radial section: radial pitting on tracheids, cross-fields with 2-4 taxodioid pits on 1-2 storeys - x200.

Fig. 10 Liquidambaroxylon speciosum Felix, 1884. a - cross section: polygonal vessels, linear rays 1-3-seriate, less distinct growth-ring boundary, solitary and grouped vessels - x50; b, c - cross-section: polygonal vessels, solitary or grouped, thick-walled fibers x100; d, e - tangential section: 2-3-seriate rays, vessels - x200; f - tangential section: scalariform perforation - x200; g - radial section: cross-field with rounded crystals in the ray-cells - x200; h - radial section: scalariform perforation – x200; i - radial section: scalariform pitting in cross field marginal ray-cells - x200.