66 
EXHIBITinx MEETING, 1952 
introduced American species S. aJterniflora Lois. (2ii = 5G). The ex- 
pected chromosome number (2n) of a hybrid between them would be 55 
-1-28, i.e., 63; this is probably the number of the French hybrid S. x 
lu’i/rautii (S. altenuiflora x *5'. nuiriti ma). S. tomiscml'i'i lias, liow- 
ever, 2n = 126, i.e., 70 -I- 56; this duplication of chromosomes lias made 
it possible for the hybrid to be fertile and true breeding. 
Tragopugoii dubius Scop., T. porrifolius L. and T. pratensis L. (all 
with 2n = 12), the diploid parent species of the two tetraploid species 
shown (Trugopogon tnirus Ownbey and T. iiiisceUus Ownbey, both with 
2n = 24), are European, but in Europe they do not grow intermixed in 
conditions permitting mass hybridization. They have become natural- 
ized, however, in North America and hybridize on a large scale in certain 
places. The fertility of the hybrids is low, but the large number of 
individuals increases the likelihood of chromosome duplication, and this 
has taken place, leading to the creation of these new species, which sur- 
pass the parent species in size and are constantly distinct from them. 
Plants of T. mirvs raised at Kew fiom seed sent by M. Ownbey are very 
uniform in character, i-eaching a height of about 6 ft.; the ligules are 
dull lilac purple with a yellow base. Plants of T. misceUus, from the 
same source, differ chiefly in having canary yellow ligules. The fruiting 
heads are as much as 12 cm. across. For fuller information reference 
should be made to Ownbey, M., ‘‘Natural hybridization and amphidi- 
ploidy in the genus Tragopogon” in Aiiter. J. Hot. 37 : 487-499 (1950). 
These new species have arisen recently. In the far distant past 
(Hdenpsis tetrahit L. (2n = 32), a species sjjread over most of Europe ami 
northern Asia, probably arose from (r. puhescens L. x (t. speciosa Miller 
(both with 2n = 16). It has been synthesized by Muntzing. 
Species which have arisen in cultivation bj' hybridization and chromo- 
some doubling are known in Aesculas, Brassica, Dahlia, J)el pliinium, 
Digitalis, Fraguria, QuaiiwcHt, Nicotiana and Suxifraga. 
W. T. Steahn. 
The British Rose Survey 
This exhibit was intended to explain the methods used and the 
results obtained in a trial season of a survey which it is hoped later to 
extend to the whole country. Volunteers are to be asked to choose small 
sample communities containing some 10-50 rose bushes, and to plot their 
characters on a special form. It is hoped in this way to obtain sufficient 
data about British roses to lead to conclusions which will elucidate the 
nature of their “species”, and the degree of reticulation present. 
P. C. Sylvester Bradley. 
Some New Ross-shire Plants 
The exhibit included herbarium sheets showing some seven new 
vice-county records for West and East Ross (v.-ec. 105, 106), and certain 
other plants of special interest from the Braemore area. The following 
species were found by R. Mackechnie and E. C. Wallace on and about 
