File:Contributions from the Botanical Laboratory, vol. 2 (1892) (20499082038).jpg

Title: Contributions from the Botanical Laboratory, vol. 2
Identifier: contributionsfro02unix (find matches)
Year: 1892 (1890s)
Authors: University of Pennsylvania. Botanical Laboratory
Subjects: Botany; Botany
Publisher: Philadelphia : University of Pennsylvania Press
Contributing Library: Penn State University
Digitizing Sponsor: Lyrasis Members and Sloan Foundation

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io6 Harshbcrger—Statistical Informatmi Concerning the The numbers marked by an asterisk show us, that as respects the number of seeds contained in any given capsule of a plant, the result of the act of fertilization has not been so successful. Xanthium canadense, Mill.—A count was made of the fruits of a plant (var. echinatum) at the seashore in sand which showed five well-developed fruits, and a plant growing in gravel near Philadelphia, which had 622 fruits. Yucca jUamentosa, L. (Adam's Needle).—This liliaceous plant is of considerable interest from a biological standpoint owing to its dependence upon the moth, Pronuba yuccasella, Riley, which passes part of its larval existence in the capsule of the plant feeding upon the seeds. The moth, previous to depositing its eggs in the soft ovary, pollinates the stigma by placing a ball of pollen from the same flower between the three stigmatic lobes. This insures the production of good seeds on which the larv^ feed. The following table gives the number of circular holes drilled by the larvai in leaving the capsule to descend to the ground, the number of good seeds, the number of seeds devoured by the larvae, and the number of abortive seeds. There are two rows of seeds in each of the three locules of the capsule ; a false partition present gives the impression that the capsule is six-celled. The fruit vessel is usually constricted in the middle through the irritation caused by the puncture made by the parent moth, so that it becomes more or less dumb-bell shaped. In the enumeration, the two rows of seeds in each cell are designated first side, second side. The ratio established is that of the fully formed, black seeds to the abortive seeds. By adding the seeds of normal appear- ance of the first two columns, lettered first and second sides, and subtracting the number of seeds devoured as well as the bad seeds of normal form not given in the table from the sum thus obtained, the figures for the last column of the table were obtained, giving the number of seeds capable of germination. Eight capsules were examined September ii, 1894, and the results tabulated, as follows : Production of Fruits and Seeds in Certain Plants. 107 II. Capsule. 1 Cell. . 2 Cell. . 3 Cell. . III. Capsule 1 Cell . . 2 Cell . . 3 Cell. .
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!i t IV. Capsule 1 Cell . . 2 Cell. . 3 Cell. Capsule. 1 Cell. . 2 Cell . . 3 Cell. . VI. Capsule. 1 Cell . . . 2 Cell. . • 3 Cell . . . VII. Capsule. 1 Cell. . . 2 Cell. . • 3 Cell. . . VIII. Capsule. 1 Cell. . . 2 Cell. . . 3 Cell. . . -T'maSln5iraterti;Zr^e seeds above and below the constriction are added. Bmpinella integerrima, Benth. & Hook.-In the Umbellifer^ a perfect fruit (cremocarp) consists of two halves (mencarps). In the table below the cremocarp only is taken mto cons.d- eration in the estimation of the number of perfect and aboruvc •

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