NETTLE FAMILY. URTICACEAE.

[Ill.u.s.tration: Fig. 30.]

=Slender Nettle.= _Urtica gracilis_ Ait. Achenes compressed, lens-shaped, ovate, rarely oval, faces similar, smooth, dull and grayish brown, .9-1.1 mm. long. Native of this country. Compared with U. dioica, this achene is thinner and shorter. Prominent in low pastures.

BUCKWHEAT FAMILY. POLYGONACEAE.

[Ill.u.s.tration: Fig. 31.]

=Knot-Gra.s.s.= _Polygonum aviculare_ L. This door-yard weed is in no sense a gra.s.s. Achenes unequally 3-sided, ovoid, acute, angles obtuse, surface, dull, light to dark reddish brown, finely granular and striate lengthwise. 1.8-2.2 mm. long, usually with the remains of calyx attached. Native of this country. Common about door-yards.

[Ill.u.s.tration: Fig. 32.]

=Wild Buckwheat.= _Polygonum Convolvulus_ L. Achenes dull, jet-black, equally 3-sided, elliptical to obovoid, minutely granular often with faint longitudinal striation, the faces often more or less concave, the angles rounded, 2.5-3.5 mm. long, sometimes with the remains of calyx attached. Introduced from Europe. Often climbing up corn stalks.

[Ill.u.s.tration: Fig. 33.]

=Erect Knotweed.= _Polygonum er.e.c.t.u.m_ L. Achenes dull, light to dark brown, unequally 3-sided, ovoid or rhombic, finely granular and striate lengthwise, the faces sometimes concave, the angles rounded, 2.5-3 mm.

long, sometimes with the remains of calyx attached. Native to this country. Of little account.

[Ill.u.s.tration: Fig. 34.]

=Smart-weed.= _Polygonum Hydropiper_ L. Achene dull, granular, light to dark reddish brown, lenticular, acutely and narrowly or broadly elliptical, or 3-sided, apex acute, concave on the sides, angles obtuse, 2-3 mm. long, sometimes with the remains of the dotted calyx attached.

Introduced from Europe. Wet land.

[Ill.u.s.tration: Fig. 35.]

=Dock-leaved or Pale Persicaria.= _Polygonum lapathifolium_ L. Achene shining, dark to chestnut brown, 2-2.2 mm. long, flattened, circular to broadly ovate with abruptly pointed apex, the base obtuse or bearing the remains of the thin calyx. Introduced from Europe. Low wet places.

=Sh.o.r.e Knotweed.= _Polygonum littorale_ Link. So far as the achenes are concerned, they are identical with those of P. aviculare above described. Native of this country. On hard or thin places, especially when newly graded.

[Ill.u.s.tration: Fig. 36.]

=Pennsylvania Persicaria=, _Polygonum Pennsylvanic.u.m_ L. Achene shining, jet-black, flattened, surface very slightly uneven and granular nearly circular with a short abrupt apex, edge rounded, 2.5-3 mm. long, often bearing the remains of the calyx. Native to this country. Occasional in annual crops.

[Ill.u.s.tration: Fig. 37.]

=Lady's Thumb.= _Polygonum Persicaria_ L. Achene shining, jet-black, surface finely uneven, much flattened with rounded edges or with 3 nearly equal concave faces, the edges faintly angled along the center, broadly ovate, base obtuse or bearing a portion of the calyx, apex abruptly pointed, 2-2.3 long. Introduced from Europe. Waste places and stubble ground.

[Ill.u.s.tration: Fig. 38.]

=Climbing False Buckwheat.= _Polygonum scandens_ L. Achene black, shining, in cross-section sides flat or concave, corners rounded, obovate, in vertical outline sides rounded to an obtuse apex, from rounded sides to base slightly concave, base acute, 3.5-4 mm. long when freed from the persistent base of the calyx. Woods and shady places. Not prominent as a weed.

[Ill.u.s.tration: Fig. 39.]

=Sorrel. Sour Dock.= _Rumex Acetosa_ L. Calyx-wings broadly ovate or orbicular, heart-shaped 3.5-4.5 mm. long, achene shining, with 3 equal sides, broadly oval, both ends abruptly pointed, the thin edges usually lighter colored than the dark brown or black convex faces, 1.5-2 mm.

long. Introduced from Europe. Not common.

[Ill.u.s.tration: Fig. 40.]

=Sheep Sorrel.= _Rumex Acetosella_ L. Achenes usually closely covered by dull reddish brown, finally roughened calyx, which is removed with difficulty; achenes shining with 3 equal sides, broadly oval, the base rounded, the apex abruptly pointed, sides convex, reddish brown or amber color, corners obtuse, darker colored. Native of this country, though in large part introduced from Europe. Very common in thin sandy meadows.

[Ill.u.s.tration: Fig. 41.]

=Narrow-leaved or Curled Dock.= _Rumex crispus_ L. Achene covered by 3 brown heart-shaped calyx-wings, which are 2.5-3.5 mm. long, each bearing an ovoid, acute tubercle; one of them is 1.5 mm. long, the other two smaller. Achene ovoid, 3-angled, shining, rich reddish-brown, 1.3-1.8 mm. long, .7-1.4 mm. wide, in transverse section the angles prominent, convex sides and angles concave near the base; base abruptly acute; when viewed vertically sides and angles concave near the apex; apex abruptly acute, compare these notes with those concerning R. obtusifolius.

Introduced from Europe. Very common on low land and in meadows.

[Ill.u.s.tration: Fig. 42.]

=Broad-leaved or Bitter Dock.= _Rumex obtusifolius_ L. Achene covered by three brown, hastate-deltoid calyx-wings, which are about 4 mm. long, each bearing an ovoid-elliptical tubercle, one of them 1.5 mm. long, the other two very narrow, rudimentary. Achenes ovoid, 3-angled, less polished than those of R. crispus, light brown, 2-2.4 mm. long, 1-1.4 mm. wide, angles in transverse section slight, sides convex, usually in a greater degree than in the specie just named, vertically sides and angles very slightly concave or straight near the base which is abruptly acute; sides and angles near the apex scarcely concave or straight; apex acute. Introduced from Europe. Not very common.

[Ill.u.s.tration: Fig. 43.]

=Patience Dock.= _Rumex Patientia_ L. Calyx-wings circular-heart shaped, 4-6 mm. long, one of them bearing a prominent ovoid tubercle; achene ovoid-elliptical, 3-angled, somewhat polished, shining, light-brown, 2.5-3.5 mm. long, 1.7-2 mm. wide, angles prominent, sides straight, in transverse section, not counting the angles, base rounded, not counting the abrupt point, when seen vertically, the sides near the apex are straight or slightly concave. Introduced from Europe. Not common.

[Ill.u.s.tration: Fig. 44.]

=Willow-leaved Dock.= _Rumex Mexica.n.u.s_ Meisn. _Rumex salicifolius_ Weinm. Calyx-wings triangular-ovate, about 3 mm. long, each bearing a large tubercle; achene dark reddish brown, smooth, shining, 1.8-2.2 mm.

long, ovoid, angles prominent, the sides viewed transversely rounded, the sides of the base as viewed vertically, rounded, straight or slightly concave, near the apex straight or concave. A native of Northeastern North America. Not common.

GOOSEFOOT OR PIGWEED FAMILY. CHENOPODIACEAE.

[Ill.u.s.tration: Fig. 45.]

=Spreading Orache.= _Atriplex patula_ L. Seeds are likely to occur in either of three different guises, depending upon the degree of their ripeness or the amount of threshing to which they have been subjected.

Achenes thin, dull, granular, gray, closely fitting the seed; seed jet-black, shining, flattened, nearly circular, edge bluntly rounded, and notched in one place, a groove leading from one side of a margined protuberance part way to the center of the face, 1.5-1.8 mm. in diameter. Introduced from Europe. Seldom troublesome.

[Ill.u.s.tration: Fig. 46.]

=Pigweed. Lamb's Quarters.= _Chenopodium alb.u.m_ L. Seeds are likely to occur in either of three different guises dependent upon the degree of their ripeness or the amount of threshing to which they have been subjected. The figure shows these conditions admirably.

Seeds black, dull or somewhat glistening, gray if not pretty clean; nearly circular; somewhat lens-shaped, one side usually more nearly flattened than the other 1-1.4 mm. in diameter, the edge bluntly rounded, the more convex side bearing a curved groove leading from one side of the marginal protuberance to near the center of the face, surface finely uneven, often with a faintly evident radiating striation.

Introduced from Europe. Very common in annual crops.

[Ill.u.s.tration: Fig. 47.]

=Mexican Tea.= _Chenopodium ambrosioides_ L. Note remarks under last preceding description concerning different stages of cleaning. Seeds smooth, shining, reddish brown, to black, thickly double convex with scarcely a trace of a hem-like margin, circular, short kidney-shaped or ovate with a notch on the edge, .6-.8 mm. long. Introduced from tropical America. Not prominent.

[Ill.u.s.tration: Fig. 48.]

=Jerusalem Oak.= _Chenopodium Botrys_ L. Concerning different states of cleaning, note remarks above under C. alb.u.m.

Seeds perfectly cleaned with great difficulty, brown to black or gray, when imperfectly cleaned, slightly flatted on two sides, circular or round, kidney-shaped, sometimes with a hem-like margin, on one side a faint groove from the margin to near the center of the face, .6-.8 mm.

in diameter. Introduced from Europe. Not prominent.