Seeds of Michigan Weeds Part 8

=Black Med.i.c.k. Nonesuch.= _Medicago lupulina_ L. Flowers light yellow; pods black, oval, much flattened, spirally coiled, causing the two extremities to nearly meet; 2-2.8 mm. long; seeds smooth, dull yellow to green, oval, flattened, kidney-shaped, with a tubercle near the middle of the concave edge or like the figure, 1.5-1.8 mm. long. Introduced from Europe and becoming frequent in gra.s.s land. Its worst feature is to supply seeds that may be mistaken for and mixed with seeds of alfalfa and red clover. The seeds differ from those of alfalfa in being more commonly egg-shaped than kidney-shaped in outline. The scar is nearer the small extremity in these seeds than in those of alfalfa. For pasture this is less valuable than white clover.

[Ill.u.s.tration: Fig. 109.]

=Alfalfa. Lucerne.= _Medicago sativa_ L. Seeds varying much in shape and size owing to their crowding in the pod when young, yellowish green to light brown. The cuts give a good idea of the variety of shapes; surface dull or somewhat glossy, often kidney shaped, with the scar in a depression near the middle, the tips may be truncate or acute or rounded, 2-2.5 mm. long in cross-section, oval; when viewed from one edge it is seen to be bent or warped in various ways, half anatropous, often seen with a slight depression extending along one edge from the scar to one end, larger seeds more often flattened than are the shorter.

A prominent forage plant, the seeds of which are often adulterated.

Native of Europe.

[Ill.u.s.tration: Fig. 110.]

=White Sweet Clover.= _Melilotus alba Desv._ Flowers white; pods straw-color to brown, coa.r.s.ely and irregularly reticulate-ridged or wrinkled; seeds smooth, dull, yellowish or greenish, more strictly elliptical-oblong in outline than those of red clover and alfalfa, bearing the broad, shallow notch near one extremity; 2-2.2 mm. long.

Introduced from Europe. Seeds used to adulterate those of alfalfa.

[Ill.u.s.tration: Fig. 111.]

=Alsike Clover.= _Trifolium hybridum_ L. Seeds dull yellowish green to very dark green, some of them mottled, lighter about the seed scar, flattened, one of the rounded edges thicker than the other, and between the two a slight groove on each side; seed rounded at one end, the other truncate with the seed scar in the middle of the truncate end. Some seeds are half anatropous, resembling in shape those of red clover; 1.3-1.2 mm. in diameter. When compared with white clover, these seeds are larger and thicker. Introduced from Europe.

[Ill.u.s.tration: Fig. 112.]

=Crimson Clover. Scarlet Clover.= _Trifolium incarnatum_ L. Seed smooth, s.h.i.+ning when not old, color light yellow to reddish yellow or brown, oval, scar about one-third the distance from the narrow end, three-fourths anatropous, 2-2.5 mm. long, very slightly compressed.

[Ill.u.s.tration: Fig. 113.]

=Red Clover.= _Trifolium pratense_ L. Seeds usually dull, pure light yellow to purple, flattened, ovoid, having the seed scar near the middle of one edge or below the middle, half anatropous, a slight depression on each side from the scar toward the broad end, the short edge thinner than the long edge, 1.5-1.8 mm. long by 1.x1.4 mm. wide. Very common.

Introduced from Europe.

=Mammoth Clover= is a variety or race or red clover, the seeds of which are indistinguishable from the seeds of red clover. As a rule they are darker in color and rather smaller. Red clover and mammoth clover are usually much mixed.

[Ill.u.s.tration: Fig. 114.]

=Low Hop-clover.= _Trifolium proc.u.mbens_ L. A low, yellow-flowered annual, often becoming a tumble-weed at maturity. Seeds plump, s.h.i.+ning, straw-colored to light brown, broad oval, very slightly flattened, 1 mm.

long, three-fourths anatropous, i. e., the scar is a very little distance from one end of the seed. A little way back of the scar on each side is a light-colored depression. Rather rapidly spreading. From Europe.

[Ill.u.s.tration: Fig. 115.]

=White Clover.= _Trifolium repens_ L. Seeds scarcely s.h.i.+ning, yellow to light brown, flattened, one of the rounded edges thinner than the other, and between the two a slight groove on each side, one end rounded, the other truncate with a slight depression in the center containing the seed scar 1.-1.2 mm. long to 1 mm. wide. The seeds that are truncate at one end are anatropous, some of them resembling those of red clover are half anatropous. Common and well known, possibly native to the northern country.

GERANIUM FAMILY. GERANIACEAE.

[Ill.u.s.tration: Fig. 116.]

=Alfilaria. Storks-bill.= _Erodium cicutarium_ (L.) L'Her. Flowers pink; achenes reddish brown, hairy, lance-shaped, the smaller end curved, hard, sharp, the larger end when mature bearing an awn spirally coiled for half its length, the sickle like apex turned to one side.

Achenes 5-6 mm. long, the coiled portion and cycle-like apex each 10-15 mm. long. True seed light brown, ovoid-lanceolate 2.5-2.7 mm. long.

Introduced from Europe.

This plant is not yet common in our state, but, judging from its behavior in the botanic garden, it is destined soon to become a bad weed. On the desert ranches of Arizona, Nevada and elsewhere, it furnishes much pasture.

[Ill.u.s.tration: Fig. 117.]

=Cut-leaved Crane's bill.= _Geranium dissectum_ L. Seed light brown, broadly oval or ovoid, surface deeply pitted requiring 25-30 pits to form one row transversely about the surface. Seed scar at the larger end from which extends a slight vertical ridge reaching nearly one-third the length of the seed. Introduced from Europe, becoming common.

[Ill.u.s.tration: Fig. 118.]

=Small-flowered Crane's bill.= _Geranium pusillum_ Burm. f. Flowers minute, pink, p.u.b.escent under a lens, slightly compressed, oval with the apex near one side of one end, about 2 mm. long, the beak nearly twice as long; seed reddish brown, smooth, oval, slightly flattened, 1.7-1.9 mm. long. Introduced from Europe, a bad weed when once established.

SPURGE FAMILY. EUPHORBIACEAE.

[Ill.u.s.tration: Fig. 119.]

=Three-Seeded Mercury.= _Acalypha Virginica_ L. Seeds 1.3-1.8 mm. long oval or obovoid, dull, light to dark reddish brown or gray, mottled with black spots, surface covered with numerous irregular vertical lines, a ridge (hilum) extending from the pointed end for about one-third the length, continuing to the broad extremity as a dark line (raphe). Native to this country. Moist land.

[Ill.u.s.tration: Fig. 120.]

=Cypress Spurge.= _Euphorbia Cyparissias_ L. Seeds dull, light lead or ash-colored, oval or oblong, circular in transverse section, 1.5-2 mm.

long, not including an irregular yellowish appendage (caruncle) at the base, a dark verticle line (raphe) extending along one side. Introduced from Europe. Thriving on thin sandy soil.

[Ill.u.s.tration: Fig. 121.]

=Toothed Spurge.= _Euphorbia dentata_ Michx. Seeds ash colored, obovoid, or globose, inconspicuously four-angled, base obtuse, irregularly tuberculate, 1 mm. or more long. It thrives in the Botanic Garden and very likely may soon spread onto Michigan farms.

[Ill.u.s.tration: Fig. 122.]

=Leafy Spurge.= _Euphorbia Esula_ L. Seeds dull, light drab colored, broad-oval, narrowed at one end, nearly circular in transverse section, 2.3 mm. long, not including a wrinkled bunch (caruncle) at the base, a dark vertical line (raphe) extending above one side opposite which is another ridge the color of the seed. Introduced from Europe.

[Ill.u.s.tration: Fig. 123.]

_Euphorbia hirsuta_ (Torr). Weigand. Seeds lead colored, obovoid approximately square in transverse section with one side narrower than the others, 4-10 irregular transverse ridges on each side, the raphe standing along one corner, about 1.2 mm. long by 7 mm. wide. Sandy soil.

[Ill.u.s.tration: Fig. 124.]

=Spotted Spurge.= _Euphorbia maculata_ L. Seeds obovoid-oblong, nearly square in cross-sections, minutely pitted and transversely wrinkled with 2-5 broken wavy ridges, a fine dark vertical line (raphe) along one corner, color reddish drab, .6-.8 mm. long. Probably introduced from west of the Rocky Mountains.

[Ill.u.s.tration: Fig. 125.]

=Upright Spotted Spurge.= _Euphorbia Preslii_ Guss. _Euphorbia nutans Lag._ Seeds lead-colored obovoid-oblong, with 4 unequal sides as seen in cross-section, pitted and transversely wrinkled, with 2-5 broken wavy ridges, a fine dark, verticle line (raphe) along one corner, 1-1.3 mm.

long. Native of eastern North America. Introduced in seeds of red clover.

[Ill.u.s.tration: Fig. 126.]

=Thyme-leaved Spurge.= _Euphorbia serpyllifolia_ Pers. Seed ash-colored, obovoid, four-angled or nearly square in cross-section, the surface covered with four or five more or less broken obtuse transverse ridges, a slender, dark line (raphe) extending from end to end on one corner.

Dry soils, like railway tracks.

CASHEW FAMILY. ANACARDIACEAE.

[Ill.u.s.tration: Fig. 127.]