Many Californian wild flowers with
bright colors seem to consist of large numbers of constant elementary
forms, as for instance, the lilies, godetias, eschscholtias and others.
They have been brought into cultivation many times, but the minutest
distinction of their elementary forms is required to attain the highest
success.
In concluding, I will point out a very interesting difficulty, which in
some cases impedes the clear understanding of elementary species. It is
the lack of self-fertilization. It occurs in widely distant families,
but has a special interest for us in two genera, which are generally
known as very polymorphous groups.
One of them is the hawkweed or _Hieracium_, and the other is the
dandelion or _Taraxacum officinale_. Hawkweeds are known as a genus in
which the delimitation of the species is almost impossible, Thousands of
forms may be cultivated side by side in botanical gardens, exhibiting
[60] slight but undoubted differentiating features, and reproduce
themselves truly by seed. Descriptions were formerly difficult and so
complicated that the ablest writers on this genus, Fries and Nageli are
said not to have been able to recognize the separate species by the
descriptions given by each other. Are these types to be considered as
elementary species, or only as individual differences? The decision of
course, would depend upon their behavior in cultures.
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