Archaeopteris Macilenta, Anatomy and Morphology of Its Frond

Abstract

The stem, rachides, and pinnae of Archaeopteris macilenta, formerly considered to be a fern of Devonian age, comprise a branch system in which the ultimate divisions heretofore referred to as pinnules are the leaves. The primary vascular system of the “frond” is a lobed siphonostele from which leaf traces arise in a spiral sequence. The anatomy of the “rachis” and of the “pinnae” is shown to be similar to that of the stem, Callixylon, which bore these “fronds.” Branching, epidermal pattern and stomates are described for the spirally arranged leaves (fertile pinnules). Attachment and dehiscence of sporangia as well as their stomates are reported. Archaeopteris is retained in the Class Progymnospermopsida which includes plants with gymnospermous anatomy and pteridophytic reproduction. It is suggested that Actinopodium, Svalbardia and Siderella are related closely to Archaeopteris and that this group of genera shows evolutionary stages in webbing of leaves and planation of branch systems. The opportunities for ontogenetic studies of the arborescent genus Archaeopteris are pointed out.

Phyllocladus and Its Bearing on the Systematics of Conifers

“…This plant has been specially noted for the possession of a large stipule.like structure at the base of the "frond" and for the presence of the so-called rachial pinnules. CARLUCCIO et al (1966) found the so-called "rachis" has a radially symmetrical vascular system like a stem and that the axes of the lateral pinnas are characterized by a similar type of vasculature. Based on these facts, they concluded that the foliar organ of Archaeopteris is not a bipinnate "fro.nd" but rather should be regarded as a planated lateral branch system.…”

Techniques for preparation of pyrite and limonite permineralizations

“…Beck's (1957) study of Tetraxylopteris provided the first clear example of the wealth of information which can be extracted from pyrite permineralizations when analyzed carefully in three planes of section. Since then, there has been a progressive increase in the utilization of pyritic specimens in analysis of the systematics and morphology of fossil plants (Beck, 1960;Carluccio et al, 1966;Marten, 1968;Stockmans, 1968;Scheckler and Banks, 1971a, b;Mustafa, 1975;Grierson, 1976;Bonamo, 1977;Serlin and Banks, 1978;Gensel, 1979;Stein, 1981; to name only a few of many possible examples). This has resulted from a developing knowledge of the chemical and structural properties of pyrite by paleobotanists, and from a growing confidence that such specimens can, indeed, produce useful, detailed data on histological features, modes of trace departure, branching patterns, and the like.…”

Anatomical reinvestigation of Archaeopteris macilenta from the Upper Devonian (Frasnian) of South China

“…Many species of Archaeopteris have been documented (Table 1) and their identification depends on morphology (especially vegetative leaves), although this method has, to a certain extent, been doubted (Carluccio et al, 1966; Guo & Wang, 2009). Archaeopteris roemeriana from Europe is very similar to A .…”

“…macilenta and A . fimbriata are gathered under a single species and the former specific epithet has priority (Carluccio et al, 1966).…”

“…Within the lignophytes, Archaeopteris is assigned to the Archaeopteridales (Beck & Wight, 1988). As one of the predominant elements of Late Devonian plant assemblages, Archaeopteris has been reported or described from all over the world (Table 1) and is well understood in morphology and anatomy (Carluccio et al, 1966; Beck, 1971; Phillips et al, 1972; Kenrick & Fairon‐Demaret, 1991; Fairon‐Demaret et al, 2001).…”