Seeds of Michigan Weeds Part 9

=Poison Ivy.= _Rhus Toxicodendron_ L. Berry nearly white, globular, about 5 mm. in diameter, drupe kidney-shaped, concave on both edges, 3 by 4.5 mm. in diameter, 2 mm. thick. To some people very poisonous to the touch; a woody shrub.

MALLOW FAMILY. MALVACEAE.

[Ill.u.s.tration: Fig. 128.]

=Indian Mallow. American Jute. Velvet Leaf.= _Abutilon Theophrasti_ Medic. _Abutilon Abutilon_ (L.) _Rusby_. Flowers yellow; seeds brown, flattened, 3.5-4 mm. long, ovoid excepting a piece cut from one side of the smaller end with 3-4 curved rows of minute slender objects on each side, the raphe extending from the pointed end to the notch on one side (half anatropous). Naturalized from northern Asia.

[Ill.u.s.tration: Fig. 129.]

=Bladder Ketmia.= _Hibiscus Trionum_ L. Seed brown, the surface dotted with numerous, ragged, light-colored pimples. Think of the shape as obovoid, and then bent somewhat to the side. As now found the seed is triangular in outline with rounded corners, considerably thinned toward one corner near which is the seed scar in the midst of a depression.

Each side of the triangle is about 2 mm. long. Introduced from Europe.

Not yet a prominent weed in Michigan.

[Ill.u.s.tration: Fig. 130.]

=Cheeses. Running Mallow.= _Malva rotundifolia_ L. Flowers white; cl.u.s.ter of 12-15 fruits flattened, circular with depression on each side, ovary circular, wedge-shaped, very slightly roughened, with radiating ridges; seeds light brown, nearly smooth, flattened, 1.4-1.7 mm. in diameter, wedge shaped, nearly circular with a small notch on the thin edge. Naturalized from Europe.

[Ill.u.s.tration: Fig. 131.]

=Whorled Mallow.= _Malva verticillata._ L. Flowers white; cl.u.s.ter of 10-12 fruits flattened, circular with depression on each side, carpel circular, wedge-shaped, about three rows of irregular shallow pits on the wide edge, radiating ridges on each flat side; seeds light brown, nearly smooth, flattened, wedge-shaped, ovate or nearly circular, 1.5-1.7 mm. long, with a small notch on the thin edge. Introduced from the west.

[Ill.u.s.tration: Fig. 132.]

=p.r.i.c.kly Sida.= _Sida spinosa_ L. Seed smooth, dull brown or reddish brown, having one side round and two sides flat or more or less concave, all edges obtuse while lying on one flat side, broadly ovoid, with one side nearly straight, scar at the larger end in the midst of a slight depression, 1.5-1.8 mm. long. Not yet common in Michigan. Introduced from the tropics.

ST. JOHN'S-WORT FAMILY. HYPERICACEAE.

[Ill.u.s.tration: Fig. 133.]

=Common St. John's-wort.= _Hyperic.u.m perforatum_ L. Seed dark brown, mottled with about twenty-four vertical rows of small scars, short oblong, 1 mm. long, a little more or less, circular in cross-section, a slight point at one or both ends. Troublesome in old meadows and pastures. From Europe.

EVENING-PRIMROSE FAMILY. ONAGRACEAE.

[Ill.u.s.tration: Fig. 134.]

=Small-flowered Gaura.= _Gaura parviflora_ Dougl. Achenes greenish brown, at first glance, having the appearance of barley, linear, swollen in the middle, more or less grooved or channeled, 6-8 mm. long.

Introduced from the South.

[Ill.u.s.tration: Fig. 135.]

=Common Evening-Primrose.= _Oenothera biennis_ L. _Onagra biennis_ (L.) Scop. Flowers yellow; seeds reddish brown or darker, surface dull, minutely ridged, very irregular in shape owing to crowding in the pod, more or less pyramidal and four or five sided, the angles acute or with a wing-like border, 1.-1.5 mm. long. Native to this country.

PARSLEY FAMILY. UMBELLIFERAE.

[Ill.u.s.tration: Fig. 136.]

=Water Hemlock.= =Mosquash Root.= =Beaver Poison.= _Cicuta maculata_ L.

Achenes, when young grow in couples joined by their flat sides, broadly oval, somewhat flattened, a single one-half oval, 2.7-3.2 mm long, with five corky yellowish white vertical stripes alternating with four brown oil tubes, the flat side with two wide light corky stripes including two brown oil tubes. The roots are very poisonous. Native to Michigan and elsewhere. Moist or wet lands.

[Ill.u.s.tration: Fig. 137.]

=Poison Hemlock.= _Conium maculatum_ L. Flowers white, achenes growing in pairs, light brown, oval, flat on one side, five ribs extending from one end to the other, between them the surface abounds in minute vertical projections, achene about 3.5 mm. long. Difficult to identify.

Introduced from Europe.

[Ill.u.s.tration: Fig. 138.]

=Wild Carrot.= _Daucus Carota_ L. Flowers white; achenes light brown, striped with white, oval, flattened, bearing numerous frail spines along the edges and in two rows lengthwise of one face, tips of spines diverging, often hooked, about 3.5 mm. long not including the spines.

Introduced from Europe. This is the cultivated carrot escaped from fields and gardens. A great pest in old meadows.

[Ill.u.s.tration: Fig. 139.]

=Wild Parsnip.= _Pastinaca sativa_ L. Flowers yellow; achenes growing in pairs, 5-6 mm. long, with flat sides together, light brown, broad oval, much flattened, surrounded by a narrow thin ridge, 9-curved shallow ribs on one side. Introduced from Europe.

MILKWEED FAMILY. ASCLEPIADACEAE.

[Ill.u.s.tration: Fig. 140.]

=Common Milkweed.= _Asclepias Syriaca_ L. Pods 8-12 cm. long, covered with soft spiny processes; seeds dull light brown, much flattened, narrowly obovate, 6.5-8 mm. long, the small end truncate, surrounded by a broad wrinkled wing-margin or hem. The concave side bears a slender vertical ridge (raphe) for two-thirds of its length; the convex side bearing fine, short ridges. Before escaping from the pods, the small end of the seed contains a cl.u.s.ter of spreading silky hairs (coma) 2-3 cm.

long. Native of this country. Often troublesome and conspicuous in light soil, occasionally becoming small, pale, with slender branches and dying.

[Ill.u.s.tration: Fig. 141.]

=Black Swallow-wort.= _Cynanchum nigrum_ (L.) Pers. _Vincetoxic.u.m nigrum_ Moench. Smooth pods of the vine about 5 cm. long; seeds brown when dry, much flattened, concave, obovate, 6-8 mm. long, nearly surrounded by a wing margin or hem, the small end truncate. The concave side bears a slender vertical ridge (raphe) for over half its length, both sides bearing fine short ridges. Before escaping from the pods, the small end of the seed contains a cl.u.s.ter of spreading silky hairs.

Introduced from Europe; not yet common, but it is persistent where once started.

MORNING GLORY FAMILY. CONVOLVULACEAE.

[Ill.u.s.tration: Fig. 142.]

=Small Bindweed.= _Convolvulus arvensis_ L. Color of seeds dull dark brown, coa.r.s.ely roughened, oval, 3-4 mm. long, one face convex, the other face sloping to the edges from a broad, central ridge, becoming mucilaginous when soaked in water. Introduced from Europe. Seldom, if ever, seeding in Michigan. On dry, poor land.

[Ill.u.s.tration: Fig. 143.]

=Hedge or Great Bindweed.= _Convolvulus sepium_ L. Pod nearly globose, about 8 mm. in diameter, usually covered by the bracts and calyx; seeds dull black or dark brown, roughened, oval, about 5 mm. long, one face convex, the other face sloping to the edges from a central ridge. Native to this country. Seldom seeding in Michigan. On low land.

[Ill.u.s.tration: Fig. 144.]

=Field Dodder.= _Cuscuta arvensis_ Beyrich. A pale yellow leafless parasitic vine; seeds dull, yellowish brown, minutely pitted, considerably resembling those of red clover, broad oval, ovoid or spherical, .7-1 mm. long, one side rounded the other often with two flat surfaces terminating in a ridge. Not uncommon with alfalfa.

[Ill.u.s.tration: Fig. 145.]

=Flax Dodder.= _Cuscuta Epilinum_ Weihe. Stems very slender, yellow or red, a parasitic vine; seeds dull, yellowish to dark brown, minutely pitted, nearly spherical, oval, ovoid, 1-1.5 mm. long. Introduced from Europe.