Lappula occidentalis (Western Stickseed)
|Also known as:||Flatspine Stickseed, Flatspine Sheepburr, Redowski's Stickseed|
|Habitat:||part shade, sun; dry sandy or gravelly soil; fields, prairies, open woods, roadsides, railroads, waste places|
|Bloom season:||May - July|
|Plant height:||6 to 24 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 8 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-linear sepals, nearly as long as the flower. Alternating with the flowers along the stem are small, leaf-like bracts. Flower stalks are erect, elongating to about 1/8 inch in fruit. Bracts, sepals and stalks are all densely covered in soft, appressed to spreading hairs.
Leaves and stems:
Leaves are basal and alternate, toothless, densely covered in soft, 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 2 inches long, up to about ¼ 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, usually single, branched in the upper plant, angled and densely covered in soft, appressed to spreading hairs.
Western Stickseed, also known as Lappula redowskii, is a circumpolar species, native to the western half of North America as well as parts of Europe and Asia. The DNR considers it introduced in Minnesota, though it may be argued that it's native in our western counties, which would be the eastern edge of its North American range, and adventive further east. It's been recorded most often in prairies and along railroads, but also in weedier areas such as roadsides, old pastures and gravel pits. We recently encountered it in a weedy vacant lot in Grand Marais, which would certainly not be a native population.
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. Western Stickseed most closely resembles the related European Stickseed (Lappula squarrosa), which has stiffer hairs and its nutlets have 2 or 3 rows 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. There are 2 varieties of L. occidentalis: var. cupulata (L. redowskii var. cupulata) has nutlets with prickles that are expanded at the base and all fused into a crown shape, and var. occidentalis (L. redowskii var. redowskii) with more slender prickles and is the species found in Minnesota.
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- Western Stickseed plant
- Western Stickseed plant
- Western Stickseed plants
- Western Stickseed with Prickly Pear Cactus and Alyssum
- hairs tend to be spreading
- mature fruit
- comparison of Lappula occidentalis and Lappula squarrosa nutlets
Photos by K. Chayka taken in Cook County and in South Dakota. Photos courtesy Peter M. Dziuk taken in Cook and Winona counties, and in South Dakota.
Have you seen this plant in Minnesota, or have any other comments about it?