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Show 296 DHECIOUS AND CHAP, VII. son compared the pollen-grains from the two forms, and those from the long-sty led flowers were to those from the short-styled, on an average fro1n ten measurements, as 10 to 9 in diameter; so that the two hermaphrodite forms of this species resemble in this respect the two male forms of R. cathartic~ls. Tho long-sty led form is not so co1nmon as the short-sty led. ~rhe latter is said by .A.sa Gray to be the 1nore fruitful of the two, as might have been expected fr01n its appearing to produce less pollen, and fro1n the grains being of smaller size; it is therefore the more highly feminine of the two. The long-styled fonn produces a greater number of flowers, which are clustered together instead of being sub-solitary; they yield some fruit, but as just stated are less fruitful than the other form, so that this forrn appears to be the 1nore masculine of the two. On the supposition that we have here an hermaphrodite plant beco1ning dicecious, there are two points deserving notice; firstly, the greater length of the pistil in the incipient 1nale form; and we have met with a nearly similar case in the male and hermaphrodite forms of Euonymus compared with the females. Secondly, the larger size of the pollengrains in the more masculine flowers, which perhaps may be attributed to their having retained their normal size ; whilst those in the incipient female flowers have been reduced. The long-sty led form of R.lanceolatus seems to correspond with the males of R. catharticus which have a longer pistil and larger pollen-grains. Light will perhaps be thrown on the nature of the forms in this genus, as soon as · the power of both kinds of pollen on both stigmas is ascertained. Several other species of Rhamnus are said to be dicecious * or sub- * Lecoq, ' Geogr. Bot.' tom. v. 1856, pp. 420-26. CHAP. VII. POLYGAMOUS PLANTS. 297 dicecious. On the other hand, R. frangula is an ordinary hermaphrodite, for my son fouli~ a large .number of bushes all bearing an equal profusion of fruit. Epigt£a repens (Ericacere ).-This plant appear~ to be in nearly the same state as Rhan~nus cathart~cus. It is described by Asa Gray* as existing under four forms. (1) With long style, perfect stigma,. and ~hort abortive stamens. (2) Shorter style, but with stigma equally perfect, short abortive stamens. These tw.o female forms amounted to 20 per cent. of the specimens received from one locality in Maine; but all the fruiting specimens belonged to the first form. (3) Style long, as in No.1, but with stigma in1perfect, stamens perfect. ( 4) Style shorter than in the last, stigma imperfect, stamens perfect. These two latter forms are evidently males. Therefore, as Asa Gray remarks, "the flowers may be classified into two kinds, each with two modifications ; the two main kinds characterised by the nature and perfection of the stigma, along with more or less abortion of the stamens ; their modifications, by the length of the style." Mr. Meehan has described t the extreme variability of the corolla and calyx in this plant, and shows that it is dicecious. It is much to be wished that the pollen-grains in the two male forms should be compared, and their fertilising power tried on the two female forms. Ilew aquijolium (Aquifoliacere ). -In the several works which I have consulted, one author alone:j: says that the holly is dicecious. During several years I *' AmericanJournalofScience' July 187o. Also' The America~ Naturalist,' 1876, p. 490. , t "Variations in Epigcea repens," Proc. Aca<l. Nat. Hoc_ of Pbila· delphia,' May 1868, p. 153. t Vaucher, 'Hist. Phys. des Plantes d' Europe,' 18-:H, tom. ii. p. 11. |