Part 11 (2/2)
[Ill.u.s.tration: Fig. 175.]
=Rugel's Broad-leaved Plantain.= _Plantago Rugelii Decne._ Seeds dark brown to black, much like those of P. major, but larger, 1.5-2.5 mm.
long slightly flattened, with edges acute, very variable in shape, oval oblong, rhomboidal, surface minutely roughened and dull, but wholly without ridge or lines as in P. major. Native of this country. Lower end of leaf-stalk red, and not clear green as in P. major. A vile pest in clover fields.
MADDER FAMILY.
[Ill.u.s.tration: Fig. 176.]
=Blue Field Madder.= _Sherardia arvensis_ L. The parts often called seeds are in reality the half-fruits ripened, each one bearing at the apex three, white, pointed, persistent calyx lobes, the inner face showing a vertical groove, and in some of the fruits the calyx is broken off. Surface dull brown, clothed with small white hairs, obovoid, 2-2.5 mm. long. Introduced from Europe, not often found in the northern states.
TEASEL FAMILY. DIPSACACEAE.
[Ill.u.s.tration: Fig. 177.]
=Wild Teasel.= _Dipsacus sylvestris_ Huds. Achene brown, minutely hairy, 4 mm. long, oblong, square in cross-section, with four vertical ribs on the angles and four on the sides. Seed suspended, anatropous, supplied with endosperm. Introduced from Europe. A weed requiring two years from seed to seeding.
COMPOSITE FAMILY. COMPOSITAE.
[Ill.u.s.tration: Fig. 178.]
=Yarrow. Milfoil.= _Achillea Millefolium_ L. Flowers white; achenes white to gray, finely striate lengthwise, flattened, oblong, tapering at the lower end, straight or curved. 2-2.3 long. Most likely introduced from Europe.
[Ill.u.s.tration: Fig. 179.]
=Ragweed.= _Ambrosia artemisiifolia_ L. Achenes hard, straw-colored to light brown or black, top-shaped, broadly oval, 2.5-3 mm. long, besides the beak 1.5 mm. long, the sides irregularly ridged vertically, with 5-10 short teeth at the apex. Sometimes the hard covering is removed by a clover huller, exposing the naked seed. Native of the U. S.
[Ill.u.s.tration: Fig. 180.]
=Great Ragweed.= _Ambrosia trifida_ L. Achenes hard, brown, more or less mottled, top-shaped, 7-8 mm. besides the stout beak 2-3 mm. long, sides with 5 stout ridges terminating in 5 short teeth. Native to the United States. River bottoms, low land, sometimes 15 ft. high.
[Ill.u.s.tration: Fig. 181.]
=Corn Camomile=. _Anthemis arvensis_ L. Achenes very variable, creamy white to light brown, oblong, wedge-shaped in outline, circular to four-angled in cross-section, more or less ribbed lengthwise, a ripple-shaped scar at the narrow end; apex truncate with a minute projection in the center, often with a narrow ridge about the margin.
About 1.7 mm. long. Introduced from Europe. Seldom troublesome in Michigan.
[Ill.u.s.tration: Fig. 182.]
=May-weed. Dog's-Fennel.= _Anthemis Cotula_ L. Outer flowers white; achenes straw color to light brown, obovoid (large end uppermost) to oblong, circular in outline, 1.3-1.8 mm. long, with 10 warty ribs.
Introduced from Europe. Old roads and waste places.
[Ill.u.s.tration: Fig. 183.]
=Great Burdock.= _Arctium Lappa._ So far as I have seen the achenes of this species, when compared with A. minus, are darker colored, rather longer, the ribs more distinct.
=Smaller Burdock.= _Arctium minus_ Beruh. Possibly only a variety of _A.
Lappa_ L., but the prevailing plant in central Michigan. I see no way of distinguis.h.i.+ng the achenes of one from the other; but it makes little difference as one burdock is as bad as another.
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