摘要:

Dispersed cuticles with surface ornamentation recovered from the Lower Old Red Sandstone (Gedinnian) of Hereford and Worcester, England, are described, named and placed in an artificial, morphologically based classification system. Four species of the new genusCosmochlainaare distinguished on the nature of the ornament. The affinities of the plants covered by such cuticles remain unknown: the cuticles are named to facilitate their use in biogeographic, stratigraphic and evolutionary studies.

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1982.tb01025.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Melissiothecais based on fusainized pollen organs of pteridospermous affinities which occur abundantly in an Upper Visean limestone at Kingswood, near Pettycur (Scotland). The new species is a pedicellate synangium composed of 50–150 sporangia each of which is embedded at its base in a parenchymatous cushion divided into lobes. The sporangia are fused along their proximal half but are free distally. Dehiscence is longitudinal. Each sporangium is supplied at its base by a single vascular strand. Prepollen is small, spherical and trilete with a rugulate exine. In ultrastructure, the nexine appears homogeneous; the sexine shows internal sculpture of granae and rod elements.Melissiothecahas not been assigned to any family, but it shows many affinities with pollen organs attributed to the Lyginopteridacea

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1982.tb01026.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

The pedicel of the female flower ofRhus lanceais distinctly articulated and usually carries three bracteoles. In the linear tetrad the micropylar megaspore forms the 8‐nucleate embryo sac of theOenothera‐type. The single, bitegmic ovule is anatropous. The ripe, loose, papery exocarp consists mainly of the outer epidermis and a sclerified hypodermis. The mesocarp is not a typical sarcocarp, since the ridges and the inner layers are sclerenchymatous. The endocarp, originating from the inner epidermis, consists of four layers and its structure and microchemistry emphasize the close alliance ofRhuswith other genera of the section Rhoideae. The endotestal seed indicates a phylogenetic affinity between the Anacardiaceae and the Burserac

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1982.tb01027.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

The timing of emergence of the three different leaf types ofMatteuccia struthiopterisis described from plants sampled over the course of a growing season. Vegetative leaves were first to appear, followed five weeks later by sporophylls and cataphylls. Leaf number and type, and total leaf dry weight per plant were assessed in weekly transects. Vegetative fronds contributed the most to total leaf dry weight, which increased during the first four weeks, and then remained constant for the remainder of the season. Cataphylls, although numerous by the end of the season, contributed little weight. Sporophylls occurred on the widest plants with the most vegetative leaves and greatest leaf weight, whereas cataphylls occurred on most plants except the smallest. Experimentally defoliated plants were re‐examined in late summer. Following initial harvest, plants often produced a second smaller set of leaves. These were restricted to vegetative leaves and cataphylls. Ability to reissue leaves, especially vegetative fronds, declined very quickly after the first few weeks in the growing season. Defoliated plants draw on the extensive reservoir of developing leaves which are found on the rhizome, thus possibly diminishing the ability of the plant to withstand regular harvesting of the young fronds for food. Individual leaves were tagged and measured over the growing season. Non‐linear regression curves fitted to the growth data for the three types of leaves indicate that growth was described best by a monomolecular growth curve for the vegetative and fertile fronds. Cataphyllar growth could be described equally well by either a monomolecular or a logistic funct

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1982.tb01028.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY