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The population variation of leaf and inflorescence characters of Stachys palustris L., S. sylvatica L. and the hybrid S. x ambigua Sm. in Britain has been studied and shows S. palustris and S. x ambigua to intergrade. S. palustris varies extensively both within and between populations and, from studies of the variation of leaf and rhizome characters in wet and dry soil, the 'dry-ground' form is shown to be an ecotype. S. sylvatica is less variable, both within and between the populations sampled. S. palustris outbreeds more readily than S. sylvatica and this difference in breeding system may be responsible for the patterns of variation exhibited by the parents. Attempts to backcross S. x ambigua to either S. palustris or S. sylvatica have been totally unsuccessful. The intergradation between S. palustris and S. x ambigua is unlikely to be the result of introgressive hybridization but is principally produced since first, S. palustris exhibits a much greater range of variation than S. sylratica and secondly, the F1 is not intermediate but closer to S. palustris. [ABSTRACT FROM AUTHOR]

Heteranthelium is a monotypic genus in the tribe Triticeae represented by an annual diploid species, H. piliferum. The spike of this species is quite different from other members of the tribe. In an attempt to elucidate the genetic relationships to other genera of the tribe, H. piliferum was crossed with various species of Aegilops, Agropyron, Eremopyrum, Henrardia and Hordeum. From these crosses F1 hybrids of (1) Heteranthelium piliferum (2x) × Eremopyrum bonaepartis (2x) and (2) Heteranthelium piliferum × Hordeum depressum (4x) were produced. At the same time F1 hybrids of (3) Eremopyrum bonaepartis × Hordeum depressum was also obtained. The hybrid under (1) showed subnormal growth and the shape of the spikes was of Eremopyrum-type, while the spikelets were intermediate. Growth of the hybrid under (2) was vigorous and the spike morphology was intermediate between the parents. A solitary spikelet with two glumes and a single spikelet at each rachis node like the Heteranthelium parent was observed but no rudimental spikelets which are the characteristic of Heteranthelium were found. Growth of the hybrid under (3) was very vigorous and the shape of the spikes was of Hordeum type. However, floral construction at each rachis node was very complicated. Rachis nodes with three glumes and a single spikelet were the most common. Sterility of all three combinations was complete. Average chromosome pairing per cell of the F1 hybrids was in (1) 0.04 bivalents and 13.93 univalents, in (2) 0.00 trivalents, 5.06 bivalents and 10.88 univalents, and in (3) 0.00 quadrivalents, 0.01 trivalents, 5.50 bivalents and 9.97 univalents. Judging from the chromosome pairing in (1), (2) and (3), a high bivalent formation in (2) and (3) is attributable to autosynthesis of chromosomes derived from the Hordeum parent. It is concluded that there is no homology among the genomes of those three species. Considering morphological features, geographical distribution, intergeneric cross-ability and genetic relationships of Heteranthelium piliferum, it is concluded that the monotypic genus Heteranthelium is a distinct entity in the tribe Triticeae. This taxon has evolved as an annual during the process of adaptation to rather dry habitats of the Mediterranean climatic regions in the course of generic differentiation of the tribe. [ABSTRACT FROM AUTHOR]

Techniques are described for the isolation of fungi inhabiting ericaceous roots and for the culture of mycorrhizas under aseptic conditions. The mycorrhizal status of a range of isolates is assessed and the distinctive features of the true endophyte are described. The biology of this fungus is considered with special reference to host specificity and its occurrence as a free living soil micro-organism. [ABSTRACT FROM AUTHOR]

The distribution of Eucalyptus cypellocarpa, E. goniocalyx and four populations apparently morphologically intermediate between these two but isolated from them is described in an area near Melbourne, Victoria. Scatter diagrams of various characters from both mature trees and progeny document and confirm that the four populations are intermediate. However, the variability of their progeny is not markedly different from that of the 'pure' species and is not as high as that of recent hybrids between the two species. It is suggested that the four populations represent either old hybrid swarms now stabilized by selection from which the parents have disappeared, or that they arose without hybridization (a) by selection from a single species or (b) as a former cline between both species. The difficulties in interpreting the origins of such stands are pointed out. [ABSTRACT FROM AUTHOR]

Various fixation methods were used to study conidium ontogeny in Stachybotrys atra Corda. Phialides arise by subterminal branching of the conidiophore. The first spore originates from the inner layer of the phialide tip, breaking the other wall layers. Thereafter spores are produced from the inside of the phialide neck where new wall layers are formed. Spores are cut off from the phialide by a septum and this splits to release the spore. As spore production ceases the phialide neck becomes plugged, the basal septum of the phialide becomes plugged and the cytoplasm vacuolates. Spores have a rough, pigmented two-layered wall and the usual organelles. [ABSTRACT FROM AUTHOR]

The cytogeographic distribution and morphology of Festuca taxa in sections Bovinae and Scariosae has been compared with the results of experimental hybridization between them. Two groups have been established, the first is predominantly Moroccan and includes F. mairei (2n = 28), F. arundinacea varieties atlantigena forma pseudo-mairei (2n = 56), letourneuxiana and cirtensis (2n = 70). These taxa are closely related to the diploid F. scariosa endemic in the Spanish Sierra Nevada. Their distinctive morphological features are due to the inclusion of the scariosa genome. The second group, predominantly European, including F. arundinacea var. glaucescens (2n = 28) and F. arundinacea var. genuina (2n = 42), is similarly associated with the diploid F. pratensis. It is suggested that evolution in this species complex involved opportunities in a previous era for hybridization between tetraploid taxa now separated geographically. From such hybrids the higher polyploids can be derived. [ABSTRACT FROM AUTHOR]

A biometric study of herbarium, wild and cultivated specimens of Caltha palustris L. s.l. in th British Isles indicates that most of the variation in the wild is environmentally determined. Further, there is no correlation of morphology with cytological differentiation. All taxa previously described within C. palustris L. are consequently regarded as untenable, with the exception of plants which differ by the single character of rooting at the nodes, and which show partial geographical differentiation. They are reduced to varietal status. [ABSTRACT FROM AUTHOR]

Presents a list of various topics in the March 1974 issue of the journal "New Phytology."