[L] Meehan, Thomas, loc. cit.
[M] It must be stated that in a later paper (Robertson, Charles: Flowers and Insects, V. Bot. Gaz., vol. XV, No. 8, pp. 199-204), Charles Robertson does not give the same results as those found by Thomas Meehan. Robertson says: “Two long stamens, one on each side of the style, furnish pollen for cross-fertilization. They have inflated anthers which probably have a bellows-like action, like the long stamen of Solanun rostratum and Rhexia virginica.” Meehan states expressly in his paper that in the case of C. marilandica he was sure no pollen was ejected, as Todd found for S. rostratum, since in the flowers, which were covered with a gauze bag, the membrane at the apex was never ruptured when the stamens were ready to fall. Robertson describes the method of extracting the pollen in C. chamæcrista in a way which is essentially the same as Todd gives for S. rostratum. He then says, in speaking of C. marilandica: “Four small stamens furnish pollen for the visitors. Bumblebees milk the pollen out of these, using their jaws, as in the case of chamæcrista.” Meehan says: “Nor was there any draw-out of the pollen, as observed by Professor Todd. It is abstracted solely through the pores; and, although I could see no evidence that such was actually the case, I suspect that fertilization could only occur through some of this extracted pollen escaping from the insect to the stigma.” It must be noted here that the method which Meehan describes for the method of opening of the anthers, the pollen being “abstracted solely through the pores,” does not agree with the method described by other observers. Leclerc du Sablon, in a paper, “Recherches sur la Structure et la Dehiscence des Anthers,” in vol. I of the seventh series of Annales des Sciences Nouvelles, discusses the anatomical modifications of the anther walls, by which dehiscence is secured. His observations cover Cassia cremophilia and Solanum. His observations do not cover a sufficient number of species to make them of the greatest value in deciding the present points. The author presents, in a condensed form, his results in: Note sur la Dehiscence des Anthers, La Belgique Horticole, vol. XXXIV, pp. 148-150, 1884. Robertson says, in speaking of the central of the three long stamens: “Bees, no doubt, force the pollen out of this as they do from the short stamens.” Meehan says: “I watched a mass of plants containing eighty-eight flower-stems on the 30th of July, and the same lot for an hour on the 6th of August, but saw no attempt to get pollen from the longer anthers or to use them in any way but as a platform. It would indeed be hardly possible for the bee to stand anywhere so as to get power to pierce the apical membranes of the longer stamens. When the flower matured and the anthers were ready to fall they were examined-the four short ones were empty sacs-the three lower ones proved that they had not served any purpose to the bees, for they were full of pollen.”
[N] This, of course, in case, as Meehan states, the large anthers do not dehisce. Of course the statement loses entirely its significance if, as Robertson states, the large stamens furnish pollen for cross-fertilization.
[O] While the experiments made upon artificial pollination were very limited, it will be seen that the pollen from the large stamen in no case fertilized over twenty-nine per cent. of the flowers pollinated from it. These flowers, however, were on the same raceme; so the low per cent. might be due to this, or to the mechanical manipulation. The suggestion that the pollen of the large stamen is less fertile than that of the smaller ones is at least interesting as a working hypothesis.
[P] Notes on Stamens of Solanaceæ, Bot. Gaz., vol. XV, pp. 103-106, 1890.
[Q] Observations on the number of seeds produced and the surety of fertilization may be of especial interest, when the wonderful distribution which this plant has attained in recent years is taken into consideration. The original habitat of S. rostratum was the southwestern portion of the United States. It has since spread over a large part of the United States, in many places being recognized as a very noxious weed. It is also reported from several European localities. Reports on the destructiveness of the plant as a weed may be found in publications of the agricultural departments, as: Dewey, L. H., A Weed Bulletin, Farmers’ Series, No. 28, U. S. Dept. Agr.; Pammel, L. H., Two Noxious Weeds, Bull. Iowa Exp. Sta., 1895. L. H. Pammel,—Distribution of Some Weeds in the United States, especially Iva xanthifolia, Lactuca scariola, Solanum carolineum, and Solanum rostratum, Proc. Iowa Acad. Sci., 1895, vol. II, pp. 103-127—gives the eastward migration of this weed up to 1895.
[R] The racemes of S. rostratum are produced by a scorpoid sympodial dichotomy of the branch, in which the racemes represent the alternate branches. At first the raceme develops much more rapidly than the bud which is to continue the main stem, and so the racemes, when flowering, are always well towards the outside of the plant.
[S] Robertson, Charles, loc. cit.
Transcriber's Notes: