Go back to Title page                             The American Triassic Flora and Global Distribution                                                    309

PRIMARAUCARIA WIELANDI Bock
Figs. 528-543
          1954 Primaraucaria wielandi Bock, p. 32-41, pls. 3-6
          1962 Primaraucaria wielandi, in Bock, p. 256, figs. 470-471

    Although this species was originally described in 1954 from reasonably dependable material, various other specimens, including scale units and branches accumulated in the meantime, are being used herein for a systematic redescription. All additional specimens of the tree were gathered in the upper Triassic of Winterpock, Virginia, which is occasionally called Clover Hill, a name of presently abandoned mining area, nearby. At the beginning of this search, about 20 years ago, only a few remains of this species were secured. By now, however, this araucarian tree has proved to be a frequent settler of the Virginia tropical rain forests, being represented by about 200 specimens of the most important structural and morphological aspect, half of them representing megastrobili. They were found singly, or on medium-sized slabs, containing exceptionally 4-5 male cones with a similar number of female ones and numerous typically foliated branches (figs. 528-532), which greatly remind of the living Araucaria imbricata, reaching a width of 4 cm, with 4-5 rhomboidal scale leaves abreast. The leaves have a shallow medial ridge and corresponding indentations parallel to the latter, which have due to the spiral overlap a somewhat lopsided appearance (figs. 528-530). In the apical area of the leaves there are short horizontal wrinkles, which obviously are shrinkage marks of glandular nature (fig. 531). In some leaves the markings are missing, in others they are only represented as a dot, or a single line. In a few branch sections (fig. 528) a spiral of normal leaves is closely followed by a spiral of thin but similarly shaped leaves, overlapping each other in pairs. This condition is credited to sex-foliation (Bock 1954, p. 39). Defoliated branches were not available, so little is known about the leaf scars, or traces. The spiral angle varies somewhat, averaging 40-50 degrees in rectangular leaf tips as in fig. 530, which also represents a proliferous growth of a m~le pericone, while fig. 529 illustrates a young, growing shoot.

    Stems were not associated with any of the leaf and cone assemblies. Large coniferous trunks persistent in the overlying Vinita sandstones, enabled farmers to build fences with them, or rotundas with good-sized trunk sections. Actually, there is no reason to suspect that these washed-in trunks, one of which found was 6 m long, were of a different species, because no other conifer was recognized at Winterpock, except for a few tips of doubtful Podozamites foliage.

    Female cones were available in various sizes and shapes. A typical cone is pictured in fig. 532, roundish to pointed, conical in shape, illustrating the tightly set assembly of typical apophyses, so well known in the recent genus Pinus. The medium-sized cone has up to 30 rows, spirally set, apophysial shields, averaging about 8 mm in width and 5 mm in height. More developed cones are about twice as large (figs. 532-534). The megastrobili do not usually disintegrate, which made it quite difficult to analyze the scale and seed components. One male cone in immature condition (fig. 535) is attached to a terminal, foliated shoot and a male pericone likewise to a larger branch (fig. 538). Both types of strobili are inseparable companions, mostly in association with foliated branches that such an assembly can hardly be set apart. All types of leaves or scales have a similar epidermal cell pattern.

Go to page 310

Web-Stat hit counter