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Darwin, Charles, 1809-1882

"The Different Forms of Flowers on Plants of the Same Species"


s, s: stigmas.)
It has long been known that several species of Linum present two forms (3/1.
Treviranus has shown that this is the case in his review of my original paper
'Botanische Zeitung' 1863 page 189.), and having observed this fact in L. flavum
more than thirty years ago, I was led, after ascertaining the nature of
heterostylism in Primula, to examine the first species of Linum which I met
with, namely, the beautiful L. grandiflorum. This plant exists under two forms,
occurring in about equal numbers, which differ little in structure, but greatly
in function. The foliage, corolla, stamens, and pollen-grains (the latter
examined both distended with water and dry) are alike in the two forms (Figure
3.4). The difference is confined to the pistil; in the short-styled form the
styles and the stigmas are only about half the length of those in the long-
styled. A more important distinction is, that the five stigmas in the short-
styled form diverge greatly from one another, and pass out between the filaments
of the stamens, and thus lie within the tube of the corolla. In the long-styled
form the elongated stigmas stand nearly upright, and alternate with the anthers.
In this latter form the length of the stigmas varies considerably, their upper
extremities projecting even a little above the anthers, or reaching up only to
about their middle.


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