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Tree lycopsids prospered in the Late Devonian and constituted a major part of the Late Paleozoic forest ecosystem that deeply impacted the Earth's climate. However, the fertile organs of these early tree lycopsids display low morphological disparity, which has hampered further knowledge about their ecological habit. Here, we report Omprelostrobus gigas gen. et sp. nov. from the Upper Devonian (Famennian) Wutong Formation at Changxing, Zhejiang, China. The collection includes aerial axes, strobili and associated roots. The strobili are the largest among coeval lycopsids to our knowledge, and are divided into proximal and distal portions by dimorphic sporophylls with differentiated laminae and probable strong photosynthetic capacity. The associated but not attached roots displaying multiple isotomous branches lack rootlets and typical rootlet scars. The varied strobili sizes of early tree lycopsids were relatively independent of their body plan, but the large strobili could suggest increased reproductive investment to overcome the disadvantages of the disturbed flooded habitat. A new species of Late Devonian fossil lycopsid with large strobili and differentiated sporophylls provides insight into reproductive investment of early tree lycopsids. [ABSTRACT FROM AUTHOR]

Shougangia bellafrom the Late Devonian (Famennian) of South China is a fern-like plant known for its morphology and now provided with anatomy and a reconstruction. Its stems contain a dissected stele with a four-ribbed and an elongate-curved primary xylem segments changing to three elongate and slightly curved segments. Primary branches have a dissected stele with three similar primary xylem segments as in stems. The primary xylem of the stems and primary branches is mesarch, and individual primary xylem segments bear peripheral protoxylem strands and are surrounded by secondary xylem.Shougangiais anatomically compared with fern-like plants, zygopterid ferns and early seed plants, verifying its uncertain affinity at class and order levels as suggested by morphology, or representing a new order within the Cladoxylopsida. On the basis of anatomy and branching pattern, it is emphasized that most fern-like plants appear evolutionarily closely related to iridopteridaleans. Secondary xylem is involved not only in mechanical support, but also more likely in enhancing water supply for fern-like plants includingShougangia. By the Late Devonian, besides the abrupt drop of atmospheric CO2levels, the presence of secondary xylem may correlate well with the primary radiation of leaves (megaphylls) of euphyllophytes (e.g. fern-like plants, sphenopsids, progymnosperms and seed plants). [ABSTRACT FROM PUBLISHER]

A heterosporous lycopsid plant is described from the Upper Devonian (Famennian) Wutong Formation, Changxing County, northern Zhejiang Province, China. The plant is known for its terminal and many detached megasporangiate strobili, most of which do not have sporophylls preserved. Some megasporangiate strobili are closely associated with a vegetative axis bearing leaf cushions and with a mass of microspores. Because of the monosporangiate strobili, the present lycopsid belongs to the Dichostrobiles of the Isoёtales sensu lato. This lycopsid conforms to Changxingia in the vegetative leaves, leaf cushions (including leaf scar and ligule pit), some parts of the megasporophyll (pedicel, heel and lamina), the megasporangium and the megaspores, although the branching pattern of axes, the arrangement and other parts of megasporophyll are still unknown. The fossils are described as Changxingia sp., and this genus is expanded with character of microspore. Hence, the previous and present data indicate that the earliest lycopsids with monosporangiate strobili from the Upper Devonian of China are consistent in Lagenicula megaspores with gula and Lycospora microspores with equatorial cingulum. In contrast, the Carboniferous lycopsids with monosporangiate strobili in Euramerica and Cathaysia show great diversification of both megaspores and microspores. [ABSTRACT FROM AUTHOR]

Pollen organ Telangiopsis sp., associated with but not attached to vegetative fronds, has been collected from the Upper Devonian (Famennian) Wutong Formation, Dongzhi County, Anhui Province, China. Fertile axes with terminal pollen organs are dichotomous for 2–4 times and may be proximally attached by fragmentary pinnules. Pollen organs are synangiate and borne on the top of a short stalk. Synangia are radial in symmetry and each consists of 4–8 elongate microsporangia fused at base. Microsporangia have a longitudinal dehiscence line and show a tapered apex. The associated stem is spiny and bears a vegetative frond which bifurcates once at the basalmost part. Frond rachises possess one order of pinna arranged alternately. Pinnules are borne alternately, planate, highly dissected, and equally dichotomous for 2–3 times. Comparisons among Late Devonian seed plants recognize several branching patterns in the fertile fronds/axes bearing terminal pollen organs. Telangiopsis sp. reinforces that the Late Devonian pollen organs are synangiate usually with basally fused microsporangia. It is suggested that the evolutionary divergence of radial and bilateral symmetries of pollen organs may have occurred in the Famennian, when the earliest seed plants evolved planate and sometimes laminate pinnules. [ABSTRACT FROM AUTHOR]

Kunia venusta gen. et sp. nov. is reported from the late Middle Devonian (Givetian) Haikou Formation near Kunming City, Yunnan Province, China. This plant has three orders of naked axes that divide pseudomonopodially. The second- and third-order axes occur in a helix. Fertile appendages are distantly spaced and helically inserted to the third-order axis; they comprise equally dichotomous branches terminated by two clusters of paired and fusiform sporangia. Sterile appendages are dichotomous and distally recurved. A comparison is made with the basal euphyllophytes including the trimerophytes, cladoxylopsids, zygopterids, stauropterids, and some relevant genera of uncertain affinity. The new plant resembles them in dichotomous appendages with terminal elongated sporangia, but differs mainly in the three orders of pseudomonopodial axes bearing helical laterals. It is thus placed in the Euphyllophytina as incertae sedis. It is suggested that an evolutionary divergence in the branching pattern and appendage morphology might have occurred in the Middle Devonian euphyllophytes, that is, maintaining three dimensions versus yielding more or less planation. [ABSTRACT FROM AUTHOR]

Abstract: Pauthecophyton gracile gen. et sp. nov. is described from the Lower Devonian (Pragian) Posongchong Formation near Zhichang Village of Wenshan District, southeastern Yunnan, China. This plant consists of pseudomonopodially and dichotomously branched main axes and lateral branches. Some laterals are pseudomonopodially divided producing three to four times dichotomously branched systems terminating in sporangia; other branches are isotomously divided six to eight times terminating in sporangia. Fusiform sporangia are grouped as fertile units; each unit, generally with two, three or four sporangia, is subtended by a branch which generally divides once or twice. Sporangia lacking twisting have a longitudinal dehiscence and contain similarly sized spores with laevigate and folded exine. Pauthecophyton probably occupies a basal position within the euphyllophytes, as one of the earliest divergent clades. It is more similar to the genus Psilophyton Dawson than to others in branching, as well as sporangial shape, terminal position and longitudinal dehiscence; these similarities, more likely to be plesiomorphic characters of the euphyllophytes, indicate that they both belong to the “trimerophyte grade”. The character of twisted sporangia in trimerophytes and the phytogeographic isolation of euphyllophytes in South China are discussed. [Copyright &y& Elsevier]