Cupressinoxylon polonicum ( Kostyniuk, 1938 ) Kraeusel, 1949

Kłusek, Marzena, 2014, Miocene coniferous woods of the Polish Carpathian Foredeep, Acta Palaeontologica Polonica 59 (3), pp. 697-708 : 703-704

Cupressinoxylon polonicum ( Kostyniuk, 1938) Kraeusel, 1949

Fig. 6A–F .

1938 Cupressinoxylon sp. ; Kostyniuk 1938: 44, pl. 3: 3, 4. 1949 Cupressinoxylon polonicum ( Kostyniuk, 1938) Kraeusel, 1949 ;

Kraeusel 1949: 175.

Material.—One fragment of coalified wood from the Hebdów locality, 10 cm long and marked as MZ LIX ( Fig. 6A–F ).

Description.—The wood is derived from branch and contains the pith. Growth rings have narrow latewood zone ( Fig. 6A ). Resin canals are absent. Axial parenchyma appears abundantly ( Fig. 6F ) and forms tangential rows. Transverse walls of parenchyma cells usually are smooth or sometimes with beadlike thickenings.

Tracheids have thick walls. On the radial walls of tracheids appears uniseriate pitting, loosely spaced in latewood Fig. 6C ). Pits are bordered, circular or oval, 11–13.5 μm in diameter. Pit apertures have circular shape in earlywood and slit-like, oblique outline in latewood. Tangential walls of tracheids possess uniseriate, sparse pits. Pits are circular, 6.5–7.5 μm in diameter. They demonstrate narrow, obliquely oriented apertures.

Uniseriate rays, typically 2–9 cells high ( Fig. 6E ), are characterised by smooth transverse and tangential walls without indentures. Cross fields contain cupressoid pits, oval or circular in outline, 6.5–8.5 μm in diameter. Pits usually are arranged in one row, 1–2 pits occur in cross field Fig. 6D ).

Two separate damages, most likely frost rings, appear within this specimen ( Fig. 6B ). Frost rings in coniferous species are composed of underlignified, deformed tracheids, collapsed cells, bent rays and traumatic parenchyma cells ( Glerum and Farrar 1966; LaMarche and Hirschboeck 1984). These disturbances have been observed in the analysed wood ( Fig. 6B ).

Remarks.—The type of tracheary and cross-field pitting, the character of ray cells and the absence of resin canals refer to the Cupressinoxylon genus. Among fossil taxa, the most similar species is Cupressinoxylon polonicum ( Kostyniuk, 1938) Kraeusel, 1949 . It is characterised by the occurrence of low, uniseriate rays and by the absence of ray tracheids. Cupressinoxylon polonicum was described for the first time from Bielany near Grójec ( Kostyniuk 1938). This wood, collected from Pliocene formations, had been initially named as Cupressinoxylon sp. , later, however, it was classified as a separate species ( Kraeusel 1949). Cupressinoxylon polonicum does not have a defined counterpart among contemporary trees. This species is most similar to the group which encompasses Platycladus Spach, 1841 , Fokienia Henry and Thomas, 1911 , Thuja Linnaeus, 1753 , Thujopsis Siebold and Zuccarini ex Endlicher, 1842 , Chamaecyparis Spach, 1841 , and Microbiota Komarov, 1923 woods. The first four genera differ from the analysed specimen because of the higher number of pits in the cross field and the presence of indentures. In the cases of Platycladus , Thuja , and Thujopsis disagreement results also from the existence of pitted transverse walls of ray cells. Moreover, Platycladus , Fokienia , and Thuja wood possesses uniseriate or biseriate bordered pits on radial walls of tracheids, while Fokienia and Thuja sometimes have biseriate or triseriate pits on tracheid tangential walls. Meanwhile, Microbiota wood is marked by the presence of smooth transverse walls of axial parenchyma cells as well as the occurrence of pitted transverse walls of ray cells ( Schweingruber 1990; García Esteban et al. 2004).All these features allow those genera to be eliminated. The analysed specimen displays the highest similarity to Chamaecyparis wood. This fact is established on the basis of cupressoid type of cross-field pitting, the presence of uniseriate pits on radial and tangential walls of tracheids and the occurrence of uniseriate rays up to 9 cells high.

Stratigraphic and geographic range.— Tertiary; Europe.

Figures

Fig. 6. Microphotographs of fossil wood Cupressinoxylon polonicum (Kostyniuk, 1938) Kraeusel, 1949 from Hebdów, Middle Miocene; specimen MZ LIX. A. Slightly disturbed growth rings (TS). B. Frost ring with deformed tracheids and rays (TS). C. Pitting on radial walls of tracheids masked by spiral checking of tracheid walls (RLS). D. Crossfield pitting (RLS). E. Short, uniseriate rays (TLS). F. Axial parenchyma (TLS). Scale bars 50 μm.