Vegetative Anatomy of Uncinia (Cyperaceae)

The vegetative anatomy of 18 (19) Uncinia spp. (Cyperaceae-Cariceae)including representatives of most taxonomic subdivisions wasstudied to determine the range of variation in certain anatomicaland morphological characters of the vegetative organs withinthe genus. The two South American species U. erinacea and U. kingii differfrom all others, the former in having a closed cylinder of sclerenchymain the culm, and the latter a grooved culm. The three tall SouthAmerican spp., U. brevicaulis, U. hamata, and U. phleoides var.trichocarpa, are characterized by adaxial intercostal fibrestrands in the leaves, and in this respect show affinities withtall New Zealand species, U. sinclairii and U. uncinata. Thelast species does not have the intercostal strands. The muchsmaller U. tenuis from S. America resembles, in the size andshape of transverse sections of leaf and culm, a group of speciesfrom New Zealand comprising U. angustifolia, U. egmontiana,and U. rupestris. To these could be added U. banksii, U. hookeri,and perhaps also U. tenella, although the last two spp. exhibitsome distinctive characters in the transverse section of theleaf and also in the leaf epidermis in surface view. No exactcounterpart to the Australian and New Zealand spp. U. divaricata,U. riparia, U. rubra and U. scabra was found amongst the S.American material. This group of spp. is distinctive, for example,because of the triangular or irregularly triangular shape oftransverse sections of the culm and the large amount of sclerenchymain transverse sections of the leaf. The range of structural variation appears to be particularlywide in the S. American spp., which represent two extreme typesin the shape of the leaf in transverse section. The other talland small species have their respective counterparts in eacharea, although they are more profusely represented in New Zealandthan in America, and therefore show a correspondingly greaterrange of structure.     

Hydropsychid (Trichoptera, Hydropsychidae) gill abnormalities as morphological biomarkers of stream pollution

1. The use of morphological gill abnormalities of hydropsychid larvae was assessed in Hydropsyche siltalai larvae exposed to cadmium in the laboratory and Cheumatopsyche lepida and H. pellucidula larvae collected from a polluted river. Two biomarkers were evaluated: (1) Hydropsychid abnormality incidence (HAI), referring to the proportion of individuals with at least some abnormalities, and (2) Hydropsychid gill abnormality indice (HYI), referring to the average number of abnormal gill tufts for all individuals. 2. Abnormality–contaminant relations for both biomarkers were established by studying gill responses along gradients of increasing cadmium and organochlorine concentrations. A cadmium gradient was verified in laboratory exposures, whereas the concentrations of polychlorinated dibenzo‐p‐dioxin (PCDD), dibenzofuran (PCDF) and diphenyl ether (PCDE) of the aquatic moss Fontinalis antipyretica were used as measures of an organochlorine gradient in the field. 3. Morphological abnormalities were easily distinguished as heavy darkening, malformation and/or reduction of single gill tufts. Darkening of the gills appeared to start either at the basal or distal ends. 4. A marked increase of HYI values with increasing Cd concentration reflected a clear abnormality‐contaminant relation, whereas the mere dicotomic classification of larvae as normal or abnormal (HAI) was less informative. High values of both HAI and HYI were associated with high contamination. A significant positive correlation was found between organochlorine concentration in mosses and biomarker values for H. pellucidula, but not for C. lepida. 5. We conclude that HAI indicates deleterious effects, but fails to quantify the severity of degradation. Use of individual gill tufts, as response units in deriving HYI, revealed a simple solution to the quantification problem. Further research into the ecological meaning, physiological background and patterns of gill abnormality is recommended for assessing the applicability and relevance of hydropsychid gill biomarkers.     

Micro- and Macro-ecological Factors in the Speciation of Obligate Parasites

The role of ecological factors in the speciation of obligateparasites is studied in the light of an example, the genusAnthracoidea,Ustilaginales. The factors may be divided into two groups inrelation to the life cycle of the parasite. The macro-ecologicalfactors are those which affect the parasite directly, i.e. mainlyduring that part of its life which it spends outside the hostplant. The micro-ecological factors exert their effect whenthe parasite is within the tissues of the host, or they areenvironmental factors in which the host is involved. For theparasite, the most critical point in its life cycle is the timewhen it infects its host, for at that time the micro-and macro-ecologicalfactors may even operate simultaneously. On morphological groundsthe genus Anthracoidea is divided into a number of highly specializedspecies. There also exist cytological grounds for this specialization:pseudo-homothallism and homothallism are postulated to limitthe possibilities of genetic recombination. However, ecological,and especially micro-ecological, factors also operate in theform of barriers limiting the exchange of genetic material betweenpopulations, and thus augmenting the effects of the cytologicalpeculiarities.     

Growth pattern of Carex arenaria (Cyperaceae)

The origin of the orthotropic aerial shoot from the plagiotropic, horizontal rhizome of Carex arenaria L. (Cyperaceae) was studied. A previously proposed adnation or fusion of the first internode of the orthotropic shoot and the fourth internode of the plagiotropic shoot could not be anatomically confirmed. The rhizome branches sympodially and the point of branching results from intercalary meristematic activity in the plagiotropic shoot.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 146 , 145–151.