a proper dividing line between the two genera. We do not anticipate a loss of the genus Bidens, however, though probably no collector would object to its thorough extermination from our flora, with all its "pitchforks" and "Spanish needles," together with the Desmodiums, which in autumn force the herborizer so extensively into their service in transporting their "fearfully and wonderfully made" legumes.

As examples of the manner in which one genus may merge into another, and one species into another, we cite two instances which have lately fallen under our observation. The first is that of the Gymnostichum Hystrix of Schreber. This remarkable grass was apparently separated from the Linnæan genus Elymus, upon the single character of the absence of glumes. In this section of the country, however, we find it with well developed glumes, which are persistent after the spikelets fall. The glumeless and intermediate forms also occur, but the one most common has rigid, awn-like glumes situated precisely as in Elymus, of nearly an inch in length, and with one prominent nerve, being therefore triangular, though appearing terete. We have never found the paleæ dentate (as figured in Pl. 11 of Gray's Manual) in any form of the species, and the "pedicels" are evidently the joints to which the glumes are attached, and are but little longer than in some species of Elymus. Were the spikelets appressed as in Elymus, it would strikingly resemble some species of the latter in aspect, and as there appears to remain no constant technical distinction of any importance, we see no reason why its former name, Elymus Hystrix L., should not be restored.

Our second case is that of Eupatorium aromaticum L., which we are convinced is but a variety of E. ageratoides L. The latter species is very common at the North in low, rich woodlands, and has large, thin and smooth leaves, which, we think, vary very little in size and shape. On reaching Maryland (except in the mountains) and the coast. this species seems to be supplanted by a having the sap peculiar flower-heads, but lower a ranching

smaller corymbs, and smaller, thicker and pubescent leaves. This species is common in Virginia in dry copses and open woodlands, but varies greatly, so that we are puzzled in selecting typical specimens. On coming to the Piedmont region, however, the problem was soon solved, for here we found that it was no longer confined to dry and somewhat exposed and sterile situations, and that in proportion to the degree of shade or richness and dampness of soil in which it grew, so the leaves became thinner and larger, and the whole plant more robust, till it could no longer be distinguished from the true E. ageratoides; and on visiting the neighboring mountains, we found the latter species growing in great abundance. If, therefore, the generally accepted rule be applied to this case, E. aromaticum must be considered to be a variety of E. ageratoides. In a very similar manner Acalypha gracilens Gray, varies into A. Virginica L., and it has very properly been reduced to the condition of a variety by Professor Gray. In this connection we would mention that we have found Eupatorium aromaticum with leaves beautifully whorled in threes. As the same arrangement has been observed in another species, it would seem that the genus is inclined towards this mode of leaf-arrangement, which makes that of E. purpureum appear less anomalous.

Before closing we would add to the list of monœcious and dicecious plants which have been found with androgynous inflorescence (see March number of the NATURALIST, p. 46) an instance of the same mode of inflorescence in Fraxinus Americana. In the spring of 1867 we observed in this county (Bedford Co., Va.) a tree of this species with panicles thoroughly androgynous; but in this instance, as if a violence had been done to nature, every flower afterwards became chane

a mass of small, contorted leaves, bendh their weight, and presenting a truly

inthemoides might also have been adduced as

a sight of these tall Virginian specimens.-A.G.

a proper dividing line between the two genera. We do not anticipate a loss of the genus Bidens, however, though probably no collector would object to its thorough extermination from our flora, with all its "pitchforks" and "Spanish needles," together with the Desmodiums, which in autumn force the herborizer so extensively into their service in transporting their "fearfully and wonderfully made" legumes.

As examples of the manner in which one genus may merge into another, and one species into another, we cite two instances which have lately fallen under our observation. The first is that of the Gymnostichum Hystrix of Schreber. This remarkable grass was apparently separated from the Linnæan genus Elymus, upon the single character of the absence of glumes. In this section of the country, however, we find it with well developed glumes, which are persistent after the spikelets fall. The glumeless and intermediate forms also occur, but the one most common has rigid, awn-like glumes situated precisely as in Elymus, of nearly an inch in length, and with one prominent nerve, being therefore triangular, though appearing terete. We have never found the paleæ dentate (as figured in Pl. 11 of Gray's Manual) in any form of the species, and the "pedicels" are evidently the joints to which the glumes are attached, and are but little longer than in some species of Elymus. Were the spikelets appressed as in Elymus, it would strikingly resemble some species of the latter in aspect, and as there appears to remain no constant technical distinction of any importance, we see no reason why its former name, Elymus Hystrix L., should not be restored.

Our second case is that of Eupatorium aromaticum L., which we are convinced is but a variety of E. ageratoides L. The latter species is very common at the North in low, rich woodlands, and has large, thin and smooth leaves, which, we think, vary very little in size and shape. On reaching Maryland (except in the mountains) and the coast this species seems to be supplanted by one having the same peculiar flower-heads, but lower and less branching, with

smaller corymbs, and smaller, thicker and pubescent leaves. This species is common in Virginia in dry copses and open woodlands, but varies greatly, so that we are puzzled in selecting typical specimens. On coming to the Piedmont region, however, the problem was soon solved, for here we found that it was no longer confined to dry and somewhat exposed and sterile situations, and that in proportion to the degree of shade or richness and dampness of soil in which it grew, so the leaves became thinner and larger, and the whole plant more robust, till it could no longer be distinguished from the true E. ageratoides; and on visiting the neighboring mountains, we found the latter species growing in great abundance. If, therefore, the generally accepted rule be applied to this case, E. aromaticum must be considered to be a variety of E. ageratoides. In a very similar manner Acalypha gracilens Gray, varies into A. Virginica L., and it has very properly been reduced to the condition of a variety by Professor Gray. In this connection we would mention that we have found Eupatorium aromaticum with leaves beautifully whorled in threes. As the same arrangement has been observed in another species, it would seem that the genus is inclined towards this mode of leaf-arrangement, which makes that of E. purpureum appear less anomalous.

Before closing we would add to the list of monoecious and dicecious plants which have been found with androgynous inflorescence (see March number of the NATURALIST, p. 46) an instance of the same mode of inflorescence in Fraxinus Americana. In the spring of 1867 we observed in this county (Bedford Co., Va.) a tree of this species with panicles thoroughly androgynous; but in this instance, as if a violence had been done to nature, every flower afterwards became changed to a mass of small, contorted leaves, bending the branches with their weight, and presenting a truly remarkable appearance.

NOTE,- Bidens cernua and B. chrysanthemoides might also have been adduced as species which run together. We beg for a sight of these tall Virginian specimens.-A.G.

A STROLL ALONG THE BEACH OF LAKE MICHIGAN.

BY W. J. BEAL.

THE South-west extremity of Lake Michigan is surrounded by a low, sandy beach, back of which are low land and marshes. Let us take a stroll with our NATURALIST friends along the lake shore south of Chicago. In place of the rocks and sea-weeds, radiates, shells and crustacea of the Atlantic coast, here are only fragments of cork, chips, sticks, now and then a mutilated specimen of an Unio, or a few small, dead gasteropods, or their empty shells. Among the land plants we shall find more to interest us. The student from Salem (Mass.), or the coast of New Jersey, recognizes the Beach Pea (Lathyrus maritimus) which we believe is never found far from the salt water, except along our great inland lakes. Here also is the Sea-rocket (Cakile Americana), a radish-like plant, and the Shore Spurge (Euphorbia polygo nifolia), growing in the loose barren sand, just as they do near the ocean. Of true marine grasses we find the Sea Sand-reed (Calamagrostis arenaria), the graceful Squirreltail Grass (Hordeum jubatum), and the pest of barefooted boys called Bur-grass or Sand Bur (Cenchrus tribuloides), and a rush (Juncus Balticus). Our seaside botanist is accustomed to see the Arrow-grass (Triglochin maritimum), on every salt marsh. It is likewise common on the marshes a little way back of the lake. In the "basin" near the city flowers a Pond-weed (Potamogeton pectinatus). Silver-weed (Potentilla anserina), is plenty in the sand, and in some places last season it sent off runners each way full seven feet in length.

We have never seen the Seaside Crowfoot (Ranunculus cymbalaria) near the lake shore, but it is very common a little way back on the low pastures and meadows on richer soil. Some of our neighbors tell us that they find the Prickly Pear (Opuntia vulgaris) on the bluffs just north of