Limits of Michigan Plants
BOTANICAL GAZEZITE. o05 that this is not necessarily so, and that Sachs' and Eichler's emergence or ligular theory may be true as to Araucariece, and that thus the cone of these plants is really and truly a single flower. In regard to Taxodinece and Cupressinece he is convinced that an inner fruit scale really exists, completely adnate to the bract and soon outgrowing it, but he does not venture to pronounce on its nature, because he thus far has no ocular demonstration of it through any
... through any anamorphosis.t Professor Celakovsky concludes that the arillus of Taxacece corresponds with the ligula of Araucariee. He speaks of the terminal position of the ovule in this tribe as of very little morphological importance, being really a lateral ovule pushed to the top of an axis.t It will be of interest to those who have been misled by contrary statements, to learn that 0. Heer, the celebrated phyto-paleontologist, has shown that geologically Abietinece and Taxodinece are the oldest conifers now known, appearing already in the Carboniferous period, while Araucariec come up much later in the Trias and Jurassic formations. But relative geological age of the different tribes of plants is of much less importance for the appreciation of their degree of development and their position in the system than some suppose. Thus the Cycadece, the Phaenogams most closely allied to the vascular cryptogams, are, as Professor Heer states, very uncertain in the Carboniferous, and make their decided appearance first in the Permian rocks; therefore much later than the higher developed conifers.-G. E. in Am. Jour. Sci. Limits of Michigan Plants.-The distribution of plants along the Great Lakes is a subject of much interest. The equalizing influence of the Lakes upon the climate of Michigan and adjacent states has resulted apparently in bringing together the two extremes of the floras considerably north and south of them. The mild winters allow southern species to come in, while the cool summers are favorable to the growth of more northern species. t The writer of this is in posession of a proliferous cone of Sequoia gigantea which seems to prove, not only that the fruit scale in this species (and consequently in the whole tribe) is homolgous with that of Abietineae, in so far as it consists of leaves cf an axillary shoot, yet that these leaves are not a single pair, but, as A. Braun has long ago suggested, in regard to Cupressinec, that there is a number of leaves, laterally coordinate and connate, bearing a number of ovules on their back. t It might be well to draw attention to the singular fact, that in the allied gymnospermous family of Gnetacece, the female flower (for such it is now assumed to be, the outer integument or utricle being considered as a twoleafed carpel) is always referred to as "terminal," whether single, double or triple, while a terminal organ can not be otherwise than single. The fact is that the female flowers are here axillary in the axils of one or more of the uppermost bracts, and, if single, are pushed to the top o' the shoot.