Achillea mittefolium. Yarrow, milfoil, nose-bleed, (p.) English agricultural ters speak of it as a plant of some value in their pastures; but it is gen. rally regarded in this country as a mere weed. Certainly it is far inferior to our usual pasture plants, and our cattle are rarely, if ever, observed to eat it.
Leaca themum vulgare. Ox-eye, daisy, white weed, (p.) This intruder from Europe has obtained alnio.t exclusive possession of many fields in eastern Pennsylvania, and the prospect of getting rid of it appears to be nearly hope less. Its propagation and diffusion are s., apid and irre sistible that one negligent sloven may b cline the smirce of a grievous annoyance to a hole neighborhood. The cultivation of hoed crops for a feu' years will rid a field of this obstruction to useful vegetation. The Corn Mari gold, Chrysanthemum legetum, a kindred plant, which is said to be such a pest to the agriculture of the Old World, happily does not appear to have found its way as yet to the -United States.
Ereathites hieracifolia. Fire Weed, (a.) This coarse native weed is remarkable for its prevalence in newly cleared grounds, especially in and around the spots where brush-wood has been burnt; hence its common name of fire-weed.
Senecio vutgaris. Common Groundsel, ragwort, (a.) A homely worthless little herb, which Prof. De Caudolle remarks migrates almost everywhere with Eurmean men. It is naturalized about the seaports of the northein States, and has lately appeared in eastern Pennsylvania.
Centaurea cyanus. Ragged Robin, blue bonnets of tbe Scotch, (a.) This European plant is often seen in our gardens, and in some places is gradually straggling into cultivated fields. As it is considered a troublesome weed among the grain crops of the Old World, it shonld be watched here, so as to prevent the blue bonnets from com ing, over the border.
C‘rsium tanceolatum. Common Thistle, (b.. This foreigner, which delights in a rich eoil, is abundantly naturalized in Pennsylvania and in the northern States generally. It is a very objectionable weed on our farms, requiring constant vigilance and attention to exclude or keep it in subjection. If permitted to mature its fruit, the expanded pappus may be seen by thou-ands floating its akenes through the air, and disseminating the obnoxious intruder far and wide. The common thistle, having no
creeping roots, is not so obstinate in resisting extirpation as some other varieties. It is easier destroyed if the roots are cut with sufficient care before i s flower ng season.
Cirsium horridutum. Yellow Thistle, (b.) This rugged, repuleive species looks like a stranger here, being hitherto chiefly restricted to the sandy seaco.ist uf New Jersey. It is certainly desirable that it should continue to be a stranger to every agricultural district.
cirsium arvense. Canada Thistle, (p.) This is perhaps the most pernicious and detestable weed that has as yet invaded the farms of our countiy. Though miscalled Canada thistle, it is believed to be indigenous to Europe, and has probably acquired that name by reaching us via Canada. The rhizoma or subterranean stem (which is perennial and very tenacious of life) lies rather below the usual depth of furrows, and hence is not destroyed by common plowing. 'Phe rhizoma ramifies and extends itself horizontally in all directions, sending up branches to the surface, where radical leaves are developed the first year, and aerial stems the second year. The plant, that is, the aerial portion, appears to die at the end of the second slimmer like a biennial, but it only dies clown to the rhizoma or subterranean stem. The numerous branches sent up from perennial rhizoma soon furnish prickly radical leaves, which cover the ground so as to prevent cattle from feeding where those leaves are. Nothing short of destroying the perennial portion of the plant will rid the ground of this pest; and this has been accom plished by a few years of continued culture, (or annual cropping of other plants whicb require frequent plowing or dressing with the hoe,) so as to prevent the develop ment ol' radical leaves, and thus deprive the rhizoma of all connection or communication with the atmosphere. We have a fetv other thistles whieli are all worthless weeds; but not being. so obnoxious as the preceding, it is nut deemed neceseary to notice them further here. Lappa major. Burdock, (b.) Eve, yhody knows this coarse, homely foreign weed; one of the earliest and Ellre.t evidences of slovenly negligence ubout farm yard.