Orobanche fasciculata (Clustered Broomrape)
|Also known as:|
|Habitat:||part shade, sun; sandy or gravelly soil; prairies, dunes, woods, bluffs, sandstone outcrops|
|Bloom season:||June - August|
|Plant height:||4 to 8 inches|
|Wetland Indicator Status:||none|
|MN county distribution (click map to enlarge):|
|National distribution (click map to enlarge):|
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Flattish cluster of up to 12 long-stalked flowers arising from the tip of the stem. Flowers are tubular and slightly curved, held more or less horizontal, ½ to 1¼ inches long, white to violet or yellow, with 5 lobes that are generally equal in size and shape, and rounded or pointed at the tip. On either side of the bottom lobe and connected to the adjacent lobes is a small fold, typically colored bright yellow. 4 stamens hug the inside of the upper tube.
The calyx cupping the flower is less than half the length of the floral tube, with 5 sharply pointed, narrowly triangular lobes about as long as or shorter than the calyx tube. The flower lobe surfaces, stalks, and outer surfaces of the floral tube and calyx are densely covered with sticky glandular hairs.
Leaves and stems:
The stem is stout, half or more of it underground, in total about as long as the flowering stalks, with 2 or more egg-shaped scales with pointed tips around the base of the cluster of flower stalks. Stems, scales and flower stalks are variably colored, yellowish to grayish-tan to reddish-brown. Plants are often single, sometimes clustered, and apparently die off after flowering and setting seed.
Fruit is a 2-sectioned capsule containing many seeds.
According to the DNR, only about 20 scattered populations of Orobanche fasciculata are known to exist in Minnesota. A plant without chlorophyll, it is an obligate parasite, completely dependent on a host plant for its moisture and carbohydrates to grow and reproduce, apparently preferring Artemisia species as hosts. Listed as Special Concern species in 1984, all three of our Orobanche species were elevated to Threatened in 2013, at risk from habitat loss due to agriculture, development, gravel mining, and invasive species. Most similar is the related One-flowered Broomrape (Orobanche uniflora), which has short, (mostly) below ground stems with up to 5 flowering stalks, flowers about ¾ inch long with calyx lobes a little longer than the calyx tube.
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- Clustered Broomrape plant, hosting on Artemisia
- Clustered Broomrape habitat
- dead plant, post-flowering
- emerging plant
- more flowers
Photos courtesy John Thayer taken in Wabasha County.
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