WEED SEEDS FOUND WITH BLUEGRASS SEEDS. Bal 
concentric rows on the similar faces; color brown, or reddish in immature seeds: 
embryo cylindrical, curved about the endosperm, its extremities nearly meeting at 
the sear. (Fig. 19, a.) 
Alsine media is very common in the United States, but is so low-growing that the 
American method of seed stripping prevents the occurrence of its seeds in abundance 
in commercial bluegrass seeds. Its seeds 
are common in European bluegrass seeds, 
€- ¢ 
particularly those of rough-stalked meadow © 
3 
grass. A 
fo) 
<i @ 
Alsine graminea (L.) Britton. ¢ 
Fie. 19.—Seeds of chickweeds: a, Alsine me- 
Seeds similar to those of Alsine media, ex- dia; b, A. graminea; c, natural size of seeds. 
cept in form and surface markings; usually ~ 
circular or oval; faces and edges somewhat rounded, finely roughened by short, inter- 
lacing ridges which are arranged more or less concentrically on the faces and 
parallel on the edges; surface dull; color grayish-brown, immature seeds reddish. 
(Fig. 19, bd.) 
Not found in American seed; frequent, although not abundant, in European seed. 
Carduus arvensis (L.) Robs. 
SS 
) 4 CANADA THISTLE. 
Seeds (akenes) 2-3 mm. long, 
oblong-lanceolate, flattened with 
obtuse edges, slightly ridged along 
each face, straight or curved edge- 
wise, sometimes facewise; apex 
truncate, often obliquely so, con- 
cave with a ring-like border; corolla scar represented by a central, conical projection; 
surface dull and mostly smooth, sometimes with several narrow, longitudinal grooves; 
color brown, the apical margin usually lighter 
and sometimes yellowish. (Fig. 20.) 
Prickles of Canada thistle and horse nettle 
(Solanum carolinense) often occur in certain 
bluegrass seeds. While the presence of the 
former is significant with respect to adultera- 
tion, the two kinds are apt to be confounded. 
The prickles of Canada thistle are 2-6 mm. 
long, very slender, yellowish, usually expanded 
and laterally flattened at the base, which con- 
sists of a portion of the leaf tissue and is darker 
colored than the rest of the prickle, somewhat 
rounded or angular in form and jagged-edged. 
(Fig. 21, cand d). 
The prickles of horse nettle (Solanum caro- Fie. 21.—Prickles often found with blue- 
Fria. 20.—Seeds of Canada thistle ( Carduus arvensis): a, well- 
matured seeds; 6, natural size of seeds; c,ashriveledseed. 
linense) are coarser, 4-8 mm. in length, light pres seed cand) Horse merle (Sola 
yellow in color, usually not darker at the base CT Ea tanga Sea eA oh 
/ 2 ’ ide size; c and d, Canada thistle (Carduus 
They are produced on the stems and the coarse arvensis) enlarged and natural size; land 
midribs of the leaves, and on breaking off have 2, characteristic forms of the bases of 
a transversely flattened scar. They occur fre- VERSE NOU SHOS Cie ypule aes 
quently in samples of Kentucky-grown Poa pratensis and are easily mistaken for 
those of Canada thistle. (Fig. 21, a and b.) 
Matured seeds, shriveled seeds, and prickles from the leaves and stems of Canada 
thistle are frequently found in Canada bluegrass seed. The presence of the prickles 
