Three-lobe Beggarticks - Bidens comosa
State Rank Reason (see State Rank above)
Collections at MONTU from Phillips Co. (Lackschewitz #8624 T21N R29E S11); Garfield Co. (Lesica #8352 T21N R31E S11); Treasure Co.: (Lesica #7806 12 September 1998, common in open soil of a gravel bar at Howry's Island ca. 1/2 mi. E of Myers Bridge T6N R35E S22); Chouteau Co.: (Lesica 7546 Uncommon in moist soil of a stabilized sandbar along the Marias R below Tiber Dam T26N R9E S33 14Sept, 1997); Yellowstone Co.: (Lesica 8036 19 Sept 1999 Common in moist soil on the shore of the Bighorn River at the boat ramp just north of I-90 T5N R34E S34)
Probably more common than these few collections would suggest since eastern Montana counties are undercollected, especially with MONTU. Grows in naturally disturbed sites (gravel bars, mud flats), so may tolerate anthropogenic disturbance.
Threelobed Beggarticks is a coarse annual herb with erect, branched stems rising up to 1 m high. The opposite, narrowly elliptic leaves, 4-14 cm long, have serrated margins, and each has one short petiole. Foliage is glabrous. Flower heads are borne on long stalks in an open inflorescence at the top of the plant. The outer involucral bracts of each head are leafy and 2-7 cm long, while the inner bracts are thin and much smaller. Disk flowers are pale yellow, and ray flowers are lacking. The flattened, carrot-shaped seeds have 2-4 minutely barbed awns that stick to clothing.
Flowering in late July-September.
The combination of awned seeds, rayless flowers, opposite leaves, dimorphic involucral bracts, and wetland habitat help place this plant into the genus Bidens. The species can be separated from others of the genus by its undivided leaves and lack of ray flowers. A hand lens may be necessary for positive determination.
Throughout much of temperate North America (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).
Observations in Montana Natural Heritage Program Database
Number of Observations:
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(Observations spanning multiple months or years are excluded from time charts)
Moist to wet soil of pond and stream margins on the plains.
- Additional ReferencesLegend: View Online Publication
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- Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.