grandiflorum was highly self-sterile, whilst H. procumbens was fairly
self-fertile. (9/6. 'Jahrb. fur wiss. Botanik' B. 7 page 464.)
Thunbergia alata kept by me in a warm greenhouse was self-sterile early
in the season, but at a later period produced many spontaneously
self-fertilised fruits. So it was with Papaver vagum: another species,
P. alpinum, was found by Professor H. Hoffmann to be quite self-sterile
excepting on one occasion (9/7. 'Zur Speciesfrage' 1875 page 47.);
whilst P. somniferum has been with me always completely self-sterile.
Eschscholtzia californica.
This species deserves a fuller consideration. A plant cultivated by
Fritz Muller in South Brazil happened to flower a month before any of
the others, and it did not produce a single capsule. This led him to
make further observations during the next six generations, and he found
that all his plants were completely sterile, unless they were crossed by
insects or were artificially fertilised with pollen from a distinct
plant, in which case they were completely fertile. (9/8. 'Botanische
Zeitung' 1868 page 115 and 1869 page 223.) I was much surprised at this
fact, as I had found that English plants, when covered by a net, set a
considerable number of capsules; and that these contained seeds by
weight, compared with those on plants intercrossed by the bees, as 71 to
100. Professor Hildebrand, however, found this species much more
self-sterile in Germany than it was with me in England, for the capsules
produced by self-fertilised flowers, compared with those from
intercrossed flowers, contained seeds in the ratio of only 11 to 100.
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