Tetraxylopteris

Abstract: Proteokalon gen. nov. is described from the Upper Devonian Catskill deposits of New York. Two orders of branching and ultimate appendages are preserved by petrifaction and by compression. The first order bears branches decussately and has a skewed four-armed protostele that occasionally dichotomizes. Second-order branches dichotomize rarely and most have T-shaped or three-armed protosteles. They bear ultimate appendages alternately, either in lateral pairs, or singly from the abaxial side. These appendages divide several times in one plane. Their vascular strand is terete. Maturation of the primary xylem is mesarch, and it consists of tracheids and parenchyma. Secondary xylem and phloem and a periderm are present. The outer cortex has a system of hypodermal fibers. Proteokalon is most similar to Tetraxylopteris and Triloboxylon of the Aneurophytales. A comparison of the stratigraphic occurrence of Protopteridium, Aneurophyton, Tetraxylopterism, Sphenoxylon, Triloboxylon, and Proteokalon suggests some evolutionary trends among the Aneurophytales. A LONG-RANGE PROJECT on the evolution of land plants has yielded a large and varied flora in the early Upper Devonian (Frasnian) of New York. Emphasis so far has been placed on the application of a variety of techniques to those specimens from which both gross morphology and anatomical structure could be obtained. Some of the results have been summarized (Banks, 1968) or listed (Banks, 1970). A floristic treatment of the material awaits accumulation of a sizeable number of plants whose descriptions can be truly meaningful. One of the most intriguing results has been recognition of a group which Beck (1960) named the progymnosperms. The slow and steady accumulation of data on these plants is illustrated by a series of papers on Tetraxylopteris (Thomas, 1935; Beck, 1957; Matten and Banks, 1967; Bonamo and Banks, 1967; Scheckler and Panks, in press). The present paper is a natural outgrowth of our increased understanding of progymnosperms. It is possible to erect a new genus, Proteokalon, only because we now have a considerable bulk of data on the existing taxa Tetraxylopteris (Beck, 1957) and Triloboxylon (Matten and Banks, 1966). We have nine specimens of the new material. They are chiefly petrifactions but do include enough preservation by compression to suggest I Received for publication 13 April 1971. This study was supported in part by NSF grants GB4493 and GB-8282, in part by Federal Hatch Funds. We thank Mrs. Jane Blanchard for her skillful assistance with the photographic work. Portions of the study were submitted (S.E.S.) in partial fulfillment of the requirements for the degree of M.S. at Cornell University. the number of orders of branching with which we are concerned. Over 55 cm of pyrite was cut into 236 transverse and 30 longitudinal sections. Preparation of the material followed the schedules outlined earlier (Scheckler and Banks, in press). The compressions were embedded in bioplastic to give greater contrast in photography and to preserve the specimens. Generic diagnosis: Proteokalo-i gen. n.-Two orders of branching known, the second bearing dichotomously divided, and planated ultimate appendages. Branching is decussate or alternate except that branches of the first and second order occasionally dichotomize. Primary xylem of branches a lobed protostele, four armed but skewed in first-order branches, three armed or T-shaped in second, circular in ultimate appendages. Branches of variable diameter depending on amount of secondary growth. Reproductive structures unknown. Type species: Proteokalon Petryi sp. n.-Plants as described in the generic diagnosis. Lobed primary xylem of branching 1-6 mm in diam depending on order of branching and position of section within branch; branch traces becoming larger distally in the branches they supply. Traces to ultimate appendages mostly circular and 0.10.7 mm wide, decreasing in size distally. Protoxylems variable in number, increasing distally in branch traces, decreasing distally in xylem of ultimate appendages. Primary xylem of tracheids and parenchyma. Protoxylem tracheids 7-20 I in width, metaxylem tracheids 20-56 j/ in width, over

Abstract: Configurations of the primary xylem strands of the progymnosperms Tetraxylopteris schmidtii, Triloboxylon ashlandicum, and Proteokalon petryi (Aneurophytales) have been determined for most levels o...

Abstract: A B S T R A C T A new genus from a Middle Devonian locality near Cairo, N. Y., is described. Actinoxylon gen. nov. is based upon pyritic petrifactions. Three orders of branching are present: penultimate branch, ultimate branch, and leaf. The penultimate branch bears spirally arranged ultimate branches and leaves, the leaves apparently replacing the branches in the spiral. The ultimate branches bear opposite to subopposite and decussate leaves. The leaves are non-planated, unwebbed structures which show at least three dichotomies. Each segment of the lefaf is terete as are all other axes. Internally the penultimate branch has a six-lobed actinostele with mesarch protoxylem areas, one or two per lobe. Secondary xylem is visible in the oldest parts of several specimens. The xylem has helical-reticulate, reticulate, scalariform and circular-pitted elements. The presumptive areas of phloem are occupied by cells with dark contents. The cortex is composed of a parenchymatous inner region and a selerenchymatous outer region. The ultimate branch traces are at first three-lobed protosteles, later becoming four-lobed. Several ultimate branch traces also possess secondary xylem while within the cortex of the penultimate branch. The leaf traces are terete strands. Below each forking of a leaf segment there is a corresponding forking of the vascular strand. Actinoxylon is compared with the progymnosperms Actinopodium, Svalbardia, Archaeopteris, Siderella, and Tetraxylopteris. The anatomy of the penultimate branch of Actinoxylon is similar to that of Actinopodium, Archaeopteris macilenta, and Siderella. The ultimate branch traces of Archaeopteris and Actinoxy7on are similar. The ultimate branch stele and pattern of trace formation in Actinoxylon is similar to the stelar configuration and trace formation in the r + 2 axes of Tetraxylopteris schmidtii. The uinwebbed leaves are similar to those of Archaeopteris fissilis, Svalbardia, and the terminal units of the Aneurophytales.