Lappula squarrosa (European Stickseed)
|Also known as:||Two-row Stickseed, Bristly Sheepburr, Bluebur|
|Life cycle:||annual, biennial|
|Habitat:||part shade, sun; average to moist disturbed soil; roadsides, waste places, fields,|
|Bloom season:||May - September|
|Plant height:||8 to 30 inches|
|Wetland Indicator Status:||none|
|MN county distribution (click map to enlarge):|
|National distribution (click map to enlarge):|
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Slender, ascending to arching racemes at the tips of branches, elongating 2 to 6 inches as the plant matures with flowers open at the tip and fruit forming below. Flowers are white to pale blue, saucer-shaped to tubular, around 1/8 inch across with five round petals fused near the base and a ring of arch-shaped, creamy colored appendages around the throat. Around the base of the flower are 5 narrow, lance-elliptic sepals about as long as the flower. Alternating with the flowers along the stem are small, leaf-like bracts, though they may be opposite the flowers or nearly so. Flower stalks are erect, elongating to about 1/8 inch in fruit. Bracts, sepals and stalks are all densely covered in stiff, mostly appressed hairs.
Leaves and stems:
Leaves are basal and alternate, toothless, densely covered in stiff, appressed to spreading hairs. Basal leaves are stalked, mostly oblong with a rounded tip, withering away by flowering time. Stem leaves are narrowly lance-oblong, ¾ to 4 inches long, up to about 3/8 inch wide, flat or folded lengthwise, pointed at the tip, wedge-shaped to rounded at the base, stalkless or nearly so, and becoming somewhat smaller as they ascend the stem. Stems are erect, single or multiple from the base, branched or not, angled and densely covered in stiff, appressed to spreading hairs.
European Stickseed has been noted as an agricultural pest, the seeds contaminating grain harvests and embedding themselves in livestock hair, a particularly bad problem for sheep herds. In Minnesota, it is weedy but not more aggressive than any other crop pest. And, of course, Round-up takes care of it. The Hackelia species are very similar, but have broader, veinier, lance-elliptic leaves and the flower stalks are drooping in fruit, where Lappula species are veinless except for the midvein, and flower stalks are erect in fruit. European Stickseed most closely resembles the related Western Stickseed (Lappula occidentalis), which has softer hairs and its nutlets have a single row of prickles (see comparison photo below). Several references note that hairs are more spreading on L. occidentalis and more appressed on L. squarrosa, and while generally true, there are enough exceptions to make this a not consistently reliable trait. Wait for fruit for a positive ID.
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- European Stickseed plant
- European Stickseed plant
- European Stickseed plants
- basal rosette
- a robust and leafy plant, pre-flowering
- hairs tend to be appressed
- developing fruit
- comparison of Lappula occidentalis and Lappula squarrosa nutlets
Photos courtesy Peter M. Dziuk taken in Hennepin and Polk counties, in his garden, and in South Dakota.
Have you seen this plant in Minnesota, or have any other comments about it?