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301
being examined from the latter alone. In addition, different
species from the botanical gardens of Copenhagen and Christiania,
some spontaneous swedish bushes, and some forms from private
gardens, among them the garden of the eminent rhodologist Rev.
R. Matsson, Hudiksvall, Sweden, have been examined. This makes
a total of about 300 bushes represenling approximately 230 diffe-
rent forms. The determination of my material — I have pressed
shoots of all fixed forms — has been controled by the distinguished
swedish expert in roses S. ArwQuisr. For most of the species, I
have confined the investigation to the development of the pollen;
for many apomictical forms, I have as well investigated Ihe reduc-
lion division in the ovules. As I hope soon to have an opportu-
nity of presenting the complete report of my studies, I shall here
briefly sum up the main results and give some of my conclusions
regarding the chief Rosa-problems.
1. The fundamental haploid chromosome number in Rosa is 7,
not 8 as was stated by STRASBURGER.
2. The genus Rosa may in cytological respect be divided into
two very different groups of species: on one side the very poly-
morphous Canina-section (in the widest sense) including such sub-
seclions as Caninae (canina + dumetorum), Afzelianae (glauca + corii-
folia), Villosae, Tomentosae, Rubiginosae, Agrestes, Junzillianae, Stylo-
sae and Rubrifoliae; on the other side all the other sections. The
latter group is distinguished by the occurrence of only paired chro-
mosomes in the diakinesis: 7, 14, or 21 pair. The former, the
Canina-section, which contains the greatest part of the Rosa-vege-
tation of Europe, is characterized by the peculiarity of showing in
the heterotype division both bivalent and single chromosomes,
usually in the proportions 7 paired plus 14 unpaired, or 7 paired
plus 21 unpaired, or 7 paired plus 28 unpaired, thus showing an
analogous chromosome condition to what was stated by ROSENBERG
in the well-known Drosera-bastard and later has been found in some
other hybrids.
3. Considering only the somatic number of chromosomes, I
have in my material found the following numbers: 14, 21, 28, 35
and 42. Further, in some specimens, I met with numbers not
being a multiple of 7 (anorthoploid forms). These bushes may be
explained as hybrids representing a later generation than F, (see
the points 20, 21 and 25).
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