He secured seeds from his plants, and grew from
them a second, and in many cases a third generation in order to estimate
the amount of variability. As a rule the forms introduced into his
garden proved constant, notwithstanding the new and abnormal conditions
under which they were propagated.
First of all we may mention three perennial forms called by him _Viola
tricolor ammotropha_, _V. tricolor coniophila_ and _V. stenochila_. The
typical _V. tricolor_ is an annual plant; sowing itself in summer and
germinating soon afterwards. The young plants thrive throughout [42] the
latter part of the summer and during the fall, reaching an advanced
stage of development of the branched stems before winter. Early in the
spring the flowers begin to open, but after the ripening of the seeds
the whole plant dies.
The three perennial species just mentioned develop in the same manner in
the first year. During their flowering period, however, and afterwards,
they produce new shoots from the lower parts of the stem. They prefer
dry and sandy soils, often becoming covered with the sand that is blown
on them by the winds. They are prepared for such seemingly adverse
circumstances by the accumulation of food in the older stems and by the
capacity of the new shoots to thrive on this food till they have become
long enough to reach the light.
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