those found on the seeds
of _Amaranthus circaezans_. There are three varieties with seeds much
the same as these. Native of low ground in central and southern
Michigan.

[Illustration: Fig. 55.]

=Prostrate Amaranth.= _Amaranthus blitoides_ S. Wats. Seeds smooth,
highly polished, jet-black, double convex, nearly circular, with a
slight notch at one edge, 1.4-1.5 mm. in diameter. Introduced from west
of the Rocky Mountains. It thrives on sandy and gravelly banks. Margin
of this seed is less pronounced than in either of the other three
noticed above. Found almost everywhere in fields of Michigan. Introduced
from tropical America. Very common in annual hoed crops.

[Illustration: Fig. 56.]

=Tumble weed.= _Amaranthus graecizans_ L. Seeds smooth, highly polished,
jet-black, double convex, nearly circular with a slight notch at one
edge, .7-1 mm. in diameter. Compare with _Acnida_. Introduced from
tropical America. It needs sand or gravel.

[Illustration: Fig. 57.]

=Slender Pigweed.= _Amaranthus hybridus_ L. (_A. chlorostachys_). Seeds
smooth, highly polished, jet-black, double convex, broadly ovate, with a
slight notch at the narrow extremity, 1.1-1.4 mm. long. Distinguished
from the preceding species by having a seed ovate instead of circular.
Introduced from tropical America. Not abundant.

[Illustration: Fig. 58.]

=Rough Pigweeds.= _Amaranthus retroflexus_ L. Sometimes incorrectly
called red-root. Seeds smooth, highly polished, jet-black, double
convex, broadly ovate, with a slight notch at the narrow end, .9-1.2 mm.
long. The seeds of this and the next preceding are ovate, while those of
the first two are very nearly circular. When seen edgewise, the
hem-like margin of this seed is less prominent then in either of the
preceding three noticed above. Found almost everywhere in annual crops.
Introduced from tropical America.

KNOTWEED FAMILY. ILLECEBRACEAE.

[Illustration: Fig. 59.]

=Knawel.= _Scleranthus annuus_ L. As the seed is single for each flower,
it is unnecessary for the ovary to open; the small, hardened, ten-angled
calyx with its five thick lobes aid in protecting and distributing the
seed within. The seed is seldom seen. Calyx straw colored, obovoid, 2
mm. long besides the five spreading, membranaceous lobes, which are
nearly as long. A low spreading plant, resembling some kinds of
chickweed.

AIZOACEAE.

[Illustration: Fig. 60.]

=Carpet-Weed.= _Mollugo verticillata_ L. Seeds orange-