I cannot close this Introduction without expressing my warm thanks to Dr. Hooker
for supplying me with specimens and for other aid; and to Mr. Thiselton Dyer and
Professor Oliver for giving me much information and other assistance. Professor
Asa Gray, also, has uniformly aided me in many ways. To Fritz Muller of St.
Catharina, in Brazil, I am indebted for many dried flowers of heterostyled
plants, often accompanied with valuable notes.
CHAPTER I.
HETEROSTYLED DIMORPHIC PLANTS: PRIMULACEAE.
Primula veris or the cowslip.
Differences in structure between the two forms.
Their degrees of fertility when legitimately and illegitimately united.
P. elatior, vulgaris, Sinensis, auricula, etc.
Summary on the fertility of the heterostyled species of Primula.
Homostyled species of Primula.
Hottonia palustris.
Androsace vitalliana.
(FIGURE 1.1. Primula veris.
Left: Long-styled form.
Right: Short-styled form.)
It has long been known to botanists that the common cowslip (Primula veris,
Brit. Flora, var. officinalis, Lin.) exists under two forms, about equally
numerous, which obviously differ from each other in the length of their pistils
and stamens. (1/1. This fact, according to Von Mohl 'Botanische Zeitung' 1863
page 326, was first observed by Persoon in the year 1794.) This difference has
hitherto been looked at as a case of mere variability, but this view, as we
shall presently see, is far from the true one.
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