ON THE ANATOMICAL STRUCTURE OF THE ARTICULATED-STEM PLANT ANNULINA NEUBURGIANA RADCZENKO

M. D. PARFENOVA

(Presented by Prof. Dr. L. L. Khalfin)

The genus Annulina was established in recent years by M. F. Neuburg on the basis of the well-known species Annularia Neuburgiana Radczenko. This new genus, as M. F. Neuburg [2] says, in its morphological structure occupies an intermediate position between Phyllotheca Brongn. and Annularia Sternb. If in Phyllotheca the radially symmetrical leaves, often in the form of a funnel, fused at the base, are directed upward more or less along the stem, and in the genus Annularia the whorls of free or only slightly uniformly fused leaves are arranged in one plane with the axis of the shoot, then in the genus Annulina the bases of the Annularia-like leaves fuse unevenly, with the formation of a bilaterally symmetrical, unilateral sheath. In this, the bases of the leaves beneath the stem—the lower or posterior leaves—are fused for a greater height, and they are arranged, without bending, at an acute angle to its axis, thereby recalling the arrangement of the leaves in the genus Phyllotheca. The leaves above the stem—the upper or anterior leaves—if they are fused, are fused only slightly; bending back, they almost cover the stem, thus recalling the arrangement of the leaves in Annularia; and although the leaf sheath departs from the normal circular nodal line, as a consequence of the fusion of the leaf bases to unequal heights the whorls prove to lie not in one plane with the axis of the shoot, as in Annularia, but at an acute angle to the axis.

Distribution of the genus Annulina: Kuznetsk Basin—Upper Balakhonka Formation $P$, Tunguska Basin—Burgukli Formation $P_1$, Pechora Basin—Vorkuta Series $P_1$ and Pechora Series $P_2$.

Annulina Neuburgiana Radczenko

Plate 1, figs. 1–7

Diagnosis. Stems ribbed, articulated, and covered with distinct longitudinal striation. Long, almost parallel-margined leaves are gathered into whorls. The tips of the leaves are long pointed; toward the base the leaves narrow more rapidly than toward the tip. The broadest part of the leaf is situated approximately in the first third of the length of the leaf, counting from the base. The vein is thick, coarse, and stands out clearly along the entire length of the leaf. The leaves are free or fuse at their bases for a short distance into a narrow ring. The central part of the whorl is slightly depressed. The leaves are covered with distinct transverse ...

Table 1

Specimen 553. Kemerovo locality, borehole 2401, depth 148 m, 310 m above the Nadkemerovo coal seam.

Figs. 2, 3, 5, 7. Anatomical structure of the epidermis, ×56:
Fig. 2 — in the area adjoining the central vein; Figs. 3, 7 — along the margin of the leaf blade; Fig. 5 — along the central vein.

Fig. 6. Reconstruction of the leaf epidermis, schematized and enlarged.

with striation, the striation not being strictly transverse, while the striae deviate toward the apex and consequently have a transverse-oblique direction. There are about 16 leaves in a whorl; leaf length 40–45 mm, width 3–4 mm; width of the midrib 1 mm; stem width approximately 3 mm.

Structure of the epidermis. The character of the epidermal cells is varied. Three types of cells may be distinguished depending on their position on the leaf surface: along the leaf margin, on the midrib, and on the sides of the rib, along it, i.e., between the marginal type of cells and the cells of the midrib. Along the margin of the leaf blade the epidermis consists of narrow, long cells oriented in the transverse direction of the leaf; the rows of such cells deviate somewhat obliquely toward the margin and toward the apex of the leaf. The walls of such cells are thin, usually more or less parallel. The ends of the cells are either bluntly rounded, or shortly pointed, or polygonally rounded, asymmetrically sharpened, etc. Rows of such cells extend irregularly along the leaf blade; approximately 4–6 rows are counted on each side of the rib. The length of such cells is 81.2–160.4 μ. Width 11.6–34.8 μ. These cells evidently account for the transverse striation of the leaf surface.

Toward the apex of the leaf the cells become narrower. At the very edge (along the margin) these cells deviate toward the apex still more strongly, and it can often be observed that the marginal cells run parallel to the leaf margin, sometimes in two or three rows. In general, the cells described deviate more strongly toward the apex of the leaf and enclose the leaf.

Closer to the midrib the cells become noticeably shorter and wider, gradually acquire polygonal outlines, and pass into rounded-polygonal cells, which are situated directly on both sides of the midrib.

These rounded-polygonal cells form a narrow band of 3–4 rows of unoriented cells on both sides of the rib. This band becomes more distinct nearer the base of the leaf. Toward the apex it seems gradually to wedge out, and, chiefly, transitional cells are observed between the marginal cells and those just described. The rounded-polygonal cells measure 58–116 μ along their greatest diameter, which is most often arranged across the leaf. The transition from these cells to the cells on the rib is not very sharp, but nevertheless clear.

On the rib the cells are strictly oriented along the leaf. They are rather large, of elongate-polygonal form. These are the largest cells on the entire leaf surface. The ends of the cells also have varied form, as in the first type, but cells with more or less pointed ends are frequently observed. Cell width 29.2–69.6 μ, length 92.8–208.8 μ.

Comparison. Of all species of the genus Annularia Sternberg, the species described differs in its large size, distinct and coarse rib, and the arrangement of the whorls—a feature characteristic of the genus.

Distribution coincides with the distribution of the genus Annulina (see genus Annulina).

LITERATURE

1. Neuburg M. F. Upper Paleozoic flora of the Kuznetsk Basin. Paleontology of the USSR, vol. XII, part 3, issue 2, 1948.

2. Biostratigraphy of the Paleozoic of the Sayano-Altai Mountain Region, vol. III. Proceedings of SNIIGGiMS, 1961.

3. Parfenova M. D. On the anatomical structure of Upper Paleozoic plants of Kuzbass. Reports of the Paleobotanical Conference. Publishing House of Tomsk State University, 1962.