Weed
stiff greenthread, plains greenthread, greenthread
AcheneAchene:
A dry, hard, one-chambered, one-seeded indehiscent fruit, as in buckwheat (Fagopyrum) or sunflower (Helianthus). The fruit wall is not united with the seed coat.
Oblanceolate
Brown
AchenesAchene:
A dry, hard, one-chambered, one-seeded indehiscent fruit, as in buckwheat (Fagopyrum) or sunflower (Helianthus). The fruit wall is not united with the seed coat. are covered with large warty structures.
One side of the acheneAchene:
A dry, hard, one-chambered, one-seeded indehiscent fruit, as in buckwheat (Fagopyrum) or sunflower (Helianthus). The fruit wall is not united with the seed coat. may be free of the warts.
PappusPappus:
Modified calyx in Asteraceae, composed of hairs, bristles, awns, or scales. The pappus-like structure attached to milkweed seeds is termed a coma. 
crown has two sharp scales appearing as horns.
Not listed
Not included
Asteraceae
Thelesperma filifolium (Hook.) A. Gray
Thelesperma intermedium Rydb.
Thelesperma trifidum (Poir.) Britton
Thelesperma filifolium (Hook.) A. Gray var. filifolium
