In a collection of Poa pratensis the variation in chromosome number and the relation between chromosome number and plant characters were studied . The material was collected at different places in the Netherlands . The number of chromosomes in the population varied from 33 to 92 . Plants with 56, 63, 70 and 77 chromosomes were in the majority. The occurrence of different chromosome numbers within almost all investigated plants led to the conclusion that aneusomaty is a rule in Poa pratensis . In the progeny of some plants chromosome numbers were found which were considerably higher than those in the mother plants . It was assumed that this rise in chromosome number was caused by fertilization of aposporous egg cells . No relation could be found between chromosome number and plant characters . A hemiploid plant (39 chromosomes) was marked off from its sibs (77 chromosomes) by a stunted growth and pale leaf colour .

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Cocksfoot is a very valuable forage grass . However, its palatability and digestibility leave to be desired.On the basis of data collected from the literature these undesirable qualities are ascribed to a. a high lignin content, b. an unfavourable K/Ca ratio and c . harshness of the leaves through the presence of silicified dentations .Directions are given for the properties mentioned under a . and b. A selection method is described for developing non-dentate plants and the results obtained so far are discussed .

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Research was conducted to study the inheritance of the characteristic 'dentated leaves' in the autotetraploid grass species Dactylis glomerata. From segregation ratios of inbred and crossbred populations the following conclusions can be drawn: 1. Harshness of leaves is a dominant character. Simplex plants have a dominant phenotype but are less strongly dentated than duplex plants. 2. From the figures obtained it cannot be established with certainty how many genes are involved in the character harshness of leaves. Most cases can be explained by assuming one dominant factor, possibly supplemented by minor genes. However, the existence of complementary factors is not excluded, while also a system of more factors with partial dominance is a possible explanation. 3. The figures can be best explained by including the occurrence of double reduction in the computations. However, it is not possible to establish the coefficient a with reliability.