Of willows (Salix) the
same two works enumerate _fifteen_ and _thirty-one_ species
respectively. The hawkweeds (Hieracium) are equally puzzling, for while
Mr. Bentham admits only seven British species, Professor Babington
describes no less than thirty-two, besides several named varieties.
A French botanist, Mons. A. Jordan, has collected numerous forms of a
common little plant, the spring whitlow-grass (Draba verna); he has
cultivated these for several successive years, and declares that they
preserve their peculiarities unchanged; he also says that they each come
true from seed, and thus possess all the characteristics of true
species. He has described no less than fifty-two such species or
permanent varieties, all found in the south of France; and he urges
botanists to follow his example in collecting, describing, and
cultivating all such varieties as may occur in their respective
districts. Now, as the plant is very common almost all over Europe and
ranges from North America to the Himalayas, the number of similar forms
over this wide area would probably have to be reckoned by hundreds if
not by thousands.
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