SELF-FERTILIZATION OF PLANTS. 367 
rule, but now found to have many exceptions, in that the pollen can fall from the 
anthers upon the stigma and so secure self-fertilization. 
© VALERIANACES.—Of this Order Valerianella supplies us with minute flowering species, 
of which V. dentata only have I had an opportunity of examining. In this species 
the anthers are incurved and dehisce very early, just before expansion of the corolla ; 
the stigma enlarges and curls backwards. I detected the pollen-tubes. The order of 
development is—corolla, stamens, pistil. The corolla is early developed, because it acts 
as a protecting organ, the calyx being almost obsolete. 
Composir£.—The great majority of this Order are undoubtedly favourable for 
cross-fertilization by insects, at least as far as the “ heads" are concerned. The con- 
trivance by which the pollen is swept out of the anther-tube by the growing style is also 
well known. There appear, however, to be many species with inconspicuous flowers, as 
well as, especially perhaps, of the conspicuously flowering Cichoracee, which are highly 
self-fertile. Though the structure is mainly the same as in the florets of the heads 
which are crossed, the stigmatic branches curl back to a much greater extent, re- 
sembling miniature rams' horns, and so insert their extremities amongst the pollen- 
grains of even their own florets as well as those of their neighbours. Such appears to 
be the ease with the Dandelion, Chicory, Hieracia, Ae Mr. Meehan notices that 
although the stigmatic branches of the Dandelion are closely adpressed at first, yet as 
they expand the pollen-grains which are attached “ to the line of the cleft” fall in 
between the branches, and thus secure self-fertilization. This, therefore, is an addi- 
tional security for being self-fertilized. Mr. Meehan also observes how the Chicory has 
all its florets fertilized before 8 o'clock, and by 9 A.M. have faded away [Tragopogon 
porrifolium does much the same]; but after the elevation of the pistil “there is not a 
cloven pistil that has not some pollen on the interior stigmatic surfaces.” He further 
adds, * I have observed the same in Dandelion and the Ox-eyed Daisy (Chrysanthemum 
Leucanthemum), as well as, I am sure, thousands that flower and perfect seed which 
no insect visits." I find my observations on the curling-back of the branches of the 
Style are corroborated by H. Müller, who alludes to more than one case and figures 
Hieracium umbellatum (* Befruchtung’ Ze p. 406). (Tab. XLIV. figs. 19 a, b.) 
Another and additional method obtains in Senecio vulgaris; for sometimes the stig- 
matic branches, though slightly separated, do ‘not protrude beyond the anther-tube or 
the corolla at all; the anthers, too, are often very slightly coherent, the ‘use’ of their 
being syngenesious is apparently no longer wanted, and so the original freedom is 
retained. Lastly, both conditions may exist in the same head, some florets having the 
styles protruding and recurved, others are not visible at all. (Tab. XLIV. fig. 20.) - 
Erigeron canadense. In this species, which has established itself about Kew, the 
inconspicuous outer florets have elongated styles and long branching stigmas, which all 
curl over the disk-florets and almost entirely conceal them. The stigmas of the latter 
do not spread out, but remain loosely in contact; these having thrust out the pollen, 
some of which adheres to the stigmas themselves, the ray (female) flowers get fertilized. 
Now although the ray-florets are fertilized by the disk, and the disk-florets are self- 
EE, m there ean; I rs be no doubt that the effect is the same in both = ! 
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