A micromorphological study of some Prunella L. (Lamiaceae) taxa and its taxonomic implications.

Pollen morphology and nutlet structures of some Prunella L. taxa were examined in detail by light microscopy (LM) and scanning electron (SEM) microscopy. Pollen grains of Prunella vary in size from small to large (Polar axis (P) = 22.25-66.04 µm, Equatorial diameter (E) = 17.56-75.64 µm). The shape of pollen grains are suboblate to prolate (P/E = 0.78-1.75) and the aperture structure is hexacolpate with granular membranes in apocolpium. Examinations of exine ornamentation show that pollen grains were recognized as bireticulate ornamentation with varying characteristics of the primary muri and secondary reticulum and four subtypes were identified. Nutlet measurements of four taxa were taken and their surfaces were examined by using SEM. While pollen ornamentations are represented by different characters among taxa, it has been concluded that nutlet surfaces do not have distinctive characters among investigated taxa. Pollen morphology of 7 taxa of Prunella has been investigated in detail for the first time.

Testing spatial theories of plant coexistence: no consistent differences in intra- and interspecific interaction distances.

Plants stand still and interact with their immediate neighbors. Theory has shown that the distances over which these interactions occur may have important consequences for population and community dynamics. In particular, if intraspecific competition occurs over longer distances than interspecific competition (heteromyopia), coexistence can be promoted. We examined how intraspecific and interspecific competition scales with neighbor distance in a target-neighbor greenhouse competition experiment. Individuals from co-occurring forbs from calcareous grasslands were grown in isolation and with single conspecific or heterospecific neighbors at distances of 5, 10, or 15 cm (Plantago lanceolata vs. Plantago media and Hieracium pilosella vs. Prunella grandiflora). Neighbor effects were strong and declined with distance. Interaction distances varied greatly within and between species, but we found no evidence for heteromyopia. Instead, neighbor identity effects were mostly explained by relative size differences between target and neighbor. We found a complex interaction between final neighbor size and identity such that neighbor identity may become important only as the neighbor becomes very large compared with the target individual. Our results suggest that species-specific size differences between neighboring individuals determine both the strength of competitive interactions and the distance over which these interactions occur.

[Genetic variation, correlation and principle component analysis on morphological characteristics of various germplasm from Prunella vulgaris].

OBJECTIVE: To study the correlation among the morphological characteristics and the spica yield of various germplasm of Prunella vulgaris. METHOD: The various P. vulgaris germplasm from all over the country were investigated by analysis of correlation analysis, path analysis and principle component analysis in a randomized block experiment. RESULT: The 6 morphological characteristics were greatly different from each other in various germplasm. The spica yield per plant had a very significantly positive correlation with the number of spica per plant and fresh leaves weight per plant, meanwhile the correlation between the spica yield per plant and spica length was very significantly. Three principal components which accounted for 87.533% of total variance were extracted from the principal component analysis. CONCLUSION: The strong growth potential, the number of spica per plant and spica length were main factors for the selection of high yield breeding of P. vulgaris.

[Pharmacognostical studies on Prunella vulgaris and Ajuga decumbens].

Ajuga decumbens Thunb. is superficially similar to Prunella vulgaris Linn. and has been used as a substitution of the latter for along time. Systematical studies on external and internal structure were carried out on the two species. By means of studies on root, stem, leaf, flower and seed, morphological characters of histology were examined and described.