=Prickly 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.
=Common St. John's-wort.= _Hypericum 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.
=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.
=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.
=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.
=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.
=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.